Computer Programming

Programming Fundamental

• Type System (Wikipedia)

Category	Description	Examples
Static Type Checking	the process of verifying the type safety of a program based on analysis of a program's text (source code).	C/C++, Java, Rust
Dynamic Type Checking	the process of verifying the type safety of a program at runtime.	JavaScript, Python, Ruby

• Strong and weak typing
• Type conversion

• Programming Paradigm

Type	Paradigm	Description	Remarks
Imperative	Imperative programming	uses statements that change a program's state
	Procedural Programming	program is built from one or more procedures (also termed subroutines or functions)	Fortran, Pascal, C
	Object-Oriented Programming		Java, C++, C#, Scala, Smalltalk
Declarative	Declarative Programming	expresses the logic of a computation without describing its control flow - logic without control flow	SQL, XQuery, Regex
	Functional Programming	treats computation as the evaluation of mathematical functions and avoids changing-state and mutable data	Clojure, Erlang, Haskell
	Reactive programming	concerned with data streams and the propagation of change

• Functional Programming Concepts
  • Higher-order function : (mathematical) functions that can either take other functions as arguments or return them as results
  • First-class function : (computer science) treats functions as first-class citizens
  • First-class citizen : an entity which supports all the operations including being passed as an argument, returned from a function, and assigned to a variable.
  • Lambda : a function definition that is not bound to an identifier (lambda abstraction, lambda expression, function literal, anonymous function)
  • Closure : a record storing a function together with an environment

• Concurrent computing
• Distributed computing
• Reactive streams

• Predicate : commonly understood to be a Boolean-valued function
• Parameter
  • A parameter or a formal argument, is a special kind of variable, used in a subroutine to refer to one of the pieces of data provided as input to the subroutine.
  • The argument in computer science is thus the actual input expression passed/supplied to a function, procedure, or routine in the invocation/call statement.
  • The term parameter (sometimes called formal parameter) is often used to refer to the variable as found in the function definition, while argument (sometimes called actual parameter) refers to the actual input supplied at function call.
  • Parameters appear in procedure definitions; arguments appear in procedure calls. Loosely, a parameter is a type, and an argument is an instance.
  • An output parameter, also known as an out parameter or return parameter, is a parameter used for output, rather than the more usual use for input. Output parameters is an idiom in some languages, notably C and C++.
• Variable Shadowing

• Software Architecture (Wikipedia)
• ISO/IEC 9126 Software Engineering — Product Quality

• Escape sequence, Escape character
• URL Template
• Canonical form
• Graphs
• MVVM(Model View ViewModel)
• Memory Management Reference

• Manning MEAP Catalog
• Wikibooks/Computing
• GrepCode.com
  • a code search engine built by developers for developers to search and browse open source Java projects.

Data Structure and Algorithm

• Algorithms by S. Dasgupta, C.H. Papadimitriou, and U.V. Vazirani
• JavaScript Algorithms and Data Structures
• Semaphore (Wikipedia)
• Compare-and-swap (Wikipedia)
• Directed acyclic graph (DAG)
• Big O notation

• How to code a URL shortener? (Apr 12 '09)

• Binary Searching in Java Without Recursion (Jun. 05, 18)
• Recursive Binary Search Algorithm in Java - Example Tutorial (APRIL 22, 2017)
• What is the difference between iteration and traversing? (May 1 '13)

Higher-order Function

Function	Description	Sample	Remark
Filter	processes a data structure (usually a list) in some order to produce a new data structure containing exactly those elements of the original data structure for which a given predicate returns the boolean value true.	stream.filter(pred), filter(func, list)
Map	applies a given function to each element of a functor, e.g. a list, returning a list of results in the same order.	stream.map(pred), map(func, list)
Fold	analyze a recursive data structure and through use of a given combining operation, recombine the results of recursively processing its constituent parts, building up a return value	stream.reduce(initval, func), reduce(func, list, initval)	Reduce, Aggregate, Inject

• Higher Order Functions: Using Filter, Map and Reduce for More Maintainable Code (Aug 18, 2017)

Container/Collection

Category	Ordered	Unique	Mutable	Java	Python	OCL
Ordered Mutable	true	false	true	List	list	Sequence
Ordered Immutable	true	false	false		turple
Ordered Unique	true	true				OrderedSet
Unordered Unique	false	true	true	Set	set	Set
Unordered Unique Immutable	false	true	false		frozenset
Unordered Immutable	false	false	true			Bag

Tree

• Tree traversal (Wikipedia)
• Tree traversal
• Java Data Structure: A Generic Tree
• vivin / tree
• vivin / GenericTree
• Problem with Generics and sub-typing in my generic Tree implementation
• Generic tree implementation in Java
• Binary Search Tree Implementation in Java
• API of javax.swing.tree.TreeModel
• API of javax.swing.tree.TreeNode
• API of javax.swing.tree.DefaultTreeModel
• API of javax.swing.tree.DefaultMutableTreeNode

Metasyntax

• BNF (Backus–Naur Form)
• EBNF (Extended Backus–Naur Form)
• ABNF (Augmented Backus–Naur Form)
• BNF/EBNF variants
• EBNF for XML

• ASN.1 (Abstract Syntax Notation One)
  • a standard and notation that describes rules and structures for representing, encoding, transmitting, and decoding data in telecommunications and computer networking

Extended BNF

Usage	Notation
Definition	=
Concatenation	,
Termination	;
Alternation	|
Optional	[ ... ]
Repetition	{ ... }
Grouping	( ... )
Comment	(* ... *)
Special Sequence	? ... ?
Exception	-

Examples

(* syntax for event signature of Solidity *)
(* https://solidity.readthedocs.io/en/v0.5.15/abi-spec.html#events *)
event-signature = event-name, "(", [ parameter-type, { ",", parameter-type } ], ")"

Pattern matching

• Regular Expression
• Glob patterns
  • * ? [abc] [a-z] [!abc] [!a-z]

• Grok pattern

Coding Convention

• What is Coding Convention
• Google Style Guide
  • C++, Objective-C, Java, Python, R, Shell, HTML/CSS, JavaScript, AngularJS, Common, XML
• Firefox Coding Style
  • C++, Java, JavaScript, Python
• FreeBSD kernel source file style guide

• Special case styles

Style	Description	Sample	Remarks
Camel Case	Spaces and punctuation are removed and the first letter of each word is capitalised.	accessToke, AccessToken	Pascal Case
Snake Case	Punctuation is removed and spaces are replaced by single underscores.	access_token, ACCESS_TOKEN
Kebab Case	Punctuation is removed and spaces are replaced by single hyphens.	access-token	Spinal Case, Lisp Case, Dash Case

Language	Guide	Remarks
Java	Code Conventions for the Java Programming Language
	Code Conventions for the JavaServer Pages Technology
	Naming Conventions for Enterprise Java Applications
Scala	Scala Style Guide
Python	PEP 8 -- Style Guide for Python Code
	Google' Python Style Guide
Rust	Rust Coding Conventions
	Rust Naming Conventions
	Rust API Guidelines / Naming	RFC 430
JavaScript	Google JavaScript Style Guide
	Firefox JavaScript Coding style
	Airbnb JavaScript Style Guide
	Code Conventions for the JavaScript Programming Language by Douglas Crockford
	JavaScript Style Guide from jQuery's Style Guides
	WordPress JavaScript Coding Standards
	Airbnb React/JSX Style Guide
C/C++	ide.googlecode.com/svn/trunk/cppguide.html Google C++ Style Guide
	C++11 use in Chromium
	OpenStack C++ Coding Standards
	FFmpeg Coding Rules
HTML/CSS	Google HTML/CSS Style Guide
	HTML Style Guide
	WordPress HTML Coding Standards
	WordPress CSS Coding Standards

Language	Public Variable/Field	Non-public Variable/Field	Local Variable	Constant	Public Method/Function	Non-public Method/Function
Java	productId	productId	prdId	MAX_COUNT_PER_DAY	makeOrder()	beforeOrder()
JavaScript	productId	productId	prdId	MAX_COUNT_PER_DAY	makeOrder()	beforeOrder()
Python
Solidity	productId	_tokenApprovals	tokenId		transferFrom()	_beforeTokenTransfer()

Object Oriented Programming

Concept	Description	Supported by	Remarks
interface	definitions of methods and values which the objects agree upon, in order to co-operate, as part of an API.		define one or more behaviors via method signatures
trait	both provide a set of methods that implement behaviour to a class, and require that the class implement a set of methods that parameterize the provided behaviour.	Rust, Scala	defines behaviors via full method definitions but not states
mix-in	a class that contains methods for use by other classes without having to be the parent class of those other classes.		described as being "included" rather than "inherited".

Glossary

Term	Definition	Description	Remarks
TL;DR(TLDR)	Too Long; Didn’t Read	Generally speaking, you should only use TLDR when summarizing a piece of text, whether you’re the author or commenter.
Foobar		metasyntactic variables and placeholder names in computer programming or computer-related documentation.	foobar, foo, bar, baz
Alice and Bob		Fictional characters commonly used as placeholders in discussions about cryptographic systems and protocols, and in other science and engineering literature where there are several participants in a thought experiment.	Alice, Bob, Carol, Dave, Eve, etc
Idempotence	the property of certain operations in mathematics and computer science whereby they can be applied multiple times without changing the result beyond the initial application.	idem + potence (same + power)
Turing completeness
Turing machine
Vanilla software	when not customized from their original form, meaning that they are used without any customizations or updates applied to them

Programming Language

• Comparison of programming languages
• List of programming languages by type
• TIOBE Programming Community Index
• Programming Language Popularity(Oct 25 2013)
• 10 Most Popular Programming Languages Today(Jun 1, 2015)

Language	Appeared in	Style	Typing Systme	Remarks
C	1972	Imperative, Procedural	Static, Weak
C++	1985	Imperative, Object-oriented, Functional, Procedural	Static
Python	1990	Imperative, Object-oriented, Functional, Procedural, Reflective	Dynamic
Java	1995	Object-oriented, Imperative, Reflective	Static, Strong
JavaScript	1995	Functional, Imperative	Dynamic
Ruby	1995	Functional, Imperative, Object-oriented, Reflective	Dynamic, Strong
Go	2009	Imperative, Functional, Object-oriented	Static, Strong, Inferred
Rust	2010	Functional, Imperative	Static, Strong, Inferred
Kotlin	2011	Object-oriented, Functional, Imperative	Static, Strong, Inferred

• Language Server Protocol (LSP)
  • A Language Server is meant to provide the language-specific smarts and communicate with development tools over a protocol that enables inter-process communication.

• Learn X in Y minutes
  • Take a whirlwind tour of your next favorite language. Community-driven!

• Lambda
• What is the difference between a 'closure' and a 'lambda'? (Oct 21 '08)
• Loop Recognition in C++/Java/Go/Scala (2011)
  • a well specified, compact benchmark in four programming languages, namely C++, Java, Go, and Scala.

• What Will Kill Java? (Sep. 30, 17)

Feature	Java	JavScript	Python	Rust
Type Checking	Static Type Checking	Dynamic Type Checking	Dynamic Type Checking	Static Type Checking
Primitive Types	boolean, char, short, int, long, float, double		int, float, complex, str	bool, char, i8, i16, i32, i64, isize, u8, u16, u32, u64, usize, f32, f64
Variable Default Mutability	mutable	mutable(let)/immutable(const)	mutable	immutable
Constant	static final MAX	const max		const MAX
Integer Literals	31, -31, 10_000_000_000, 0x33FE (hexadecimal), 0b101010 (binary)
Floating Point Literals	0.5, -0.5, 10f, 89d, 3.1415e0, 1.0e-6d
Boolean Literals		true, false	True, False
Character Literals
String Literals
Formatted String Literals	N/A	`Hi, ${name}`	f'Hi, {name}'
Regex Support
Arithmetic Operators	+ (addition) - (substraction) * (multiplication) / (division) % (modulus)		+ (addition) - (substraction) * (multiplication) / (division) % (modulus) ** (exponent) // (floor division)	+ (addition) - (substraction) * (multiplication) / (division) % (modulus)
Destructuring Assignment	No		Yes	Yes
Variable Arguments	Logger.debug(Marker marker, String format, Object... args)	foo(a, b, ...args)	foo(a, b, *args)
Multiple Return	No		Yes	Yes
If Expression	condition ? a : b	condition ? a : b	a if condition else b
Lamda Expression	(a, b) -> (a*a + b*b)	(a, b) => (a*a + b*b)	lamda a, b: a*a + b*b	|x| x * 2
Container Types	Array, Set, List, Map		set, list, tuple, dict
Array Literals
List Literals			['dot', 'cat', 'snake']
Map Literals	N/A		{'dog': 'bark', 'cat': 'meow', 'snake': 'hiss'}
Set Literals	N/A		{'dog', 'cat', 'snake'}
Ordered Container Slicing		Array.slice(start[, end])	seq[start:end:step]

Java

• >> On Java

Python

• >> On Python

JavaScript

• >> On JavaScript

Scala

• >> On Scala

Rust

• https://www.rust-lang.org/

References

• The Rust Programming Language (book)
• The Rust RFC Book
• The Rust community’s crate registry

• Operators
• Range expressions
• Match expressions

Primitive Types

• Data Types

Category	Type	Definition	Size	Literals	Remarks
Boolean	bool	1 Byte	true, false
Character	char	unicode scalar value	4 Bytes	'a', 'Z'
Integer	i8	8-bit signed integer type	1 Byte		[-128, 127]
	i16	16-bit signed integer type	2 Bytes
	i32	32-bit signed integer type	4 Bytes
	i64	64-bit signed integer type	8 Bytes
	isize
	u8	8-bit unsigned integer type	1 Byte		[0, 255]
	u16	16-bit unsigned integer type	2 Bytes
	u32	32-bit unsigned integer type	4 Bytes
	u64	64-bit unsigned integer type	8 Bytes
	usize
Floating Point	f32	32-bit floating point type	4 Bytes
	f64	64-bit floating point type	8 Bytes

API Documentation

Crate	Description	Remarks
std	the foundation of portable Rust software, a set of minimal and battle-tested shared abstractions for the broader Rust ecosystem.	core types, primitives, standard macros, I/O, multithreading
test	support code for rustc's built in unit-test and micro-benchmarking framework.
rand	utilities for random number generation.

Cargo CLI

• Cargo Commands

Command	Description	Remarks
cargo build	Compile local packages and all of their dependencies.
cargo update	Update dependencies as recorded in the local lock file(Cargo.lock).

Go

• https://golang.org/
• GoDoc : documentation for Go packages on Bitbucket, GitHub, Google Project Hosting and Launchpad.

References

• Documentation
• Language Specification
  • Types
  • Literals

• Command Documentation

command	description	remarks
go build	compile packages and dependencies
go install	compile and install packages and dependencies
go get	download and install packages and dependencies

• Package Documentation

Category	Package	Description	Remarks
standard	fmt	implements formatted I/O with functions analogous to C's printf and scanf.
standard	http	provides HTTP client and server implementations.
standard	path/filepath	implements utility routines for manipulating filename paths in a way compatible with the target operating system-defined file paths.
go-resiliency	retrier	implements the "retriable" resiliency pattern for Go

• Books
  • An Introduction to Programming in Go
  • GO BOOTCAMP
  • Ethereum Development with Go
    • This little guide book is to serve as a general help guide for anyone wanting to develop Ethereum applications using the Go programming language.

• Sources
  • net/http.Transport
  • net/http.Client

Readings

• Learn Concurrency
• Network programming with Go
• The GOPATH environment variable
• cmd/go: assume GOPATH=$HOME/go if not set
• Golang tutorial series

• 10 open source projects proving the power of Go (Nov 11, 2014)
• 50 Shades of Go: Traps, Gotchas, and Common Mistakes for New Golang Devs

Fundamental

• Ultimate Visual Guide to Go Enums (Oct 19, 2017)
• Go by Example: String Functions
• Can you run a Golang compiled binary without Golang installed?

OOP

• Structs Instead of Classes - OOP in Go (21 AUGUST 2017)

Documenting

• Godoc: documenting Go code (31 March 2011)

• How do you mark code as deprecated in Go? (Oct 21 '11)

Profiling

• Package runtime/pprof
• Package net/http/pprof
• pprof end-user documentation

• Profiling Go Programs (24 June 2011)
• The output of go tool pprof --help
• Profiling Go programs with pprof
• Profiling and optimizing Go web applications (March 13, 2017)
• Profiling and creating call graphs for Go programs with "go tool pprof" (2013-08-08)
• Profiling Golang

Networking

• HTTPS and Go
• TLS Mutual Auth in GoLang (June 25, 2015)

Frameworks

Libraries

Gorilla WebSocket

• https://github.com/gorilla/websocket
• Desc. : A WebSocket implementation for Go.

• Readings
  • API Reference

Viper

• https://github.com/spf13/viper
• Desc. : a complete configuration solution for go applications including 12 factor apps.
• License : The MIT License

• Readings
  • Using Viper for some Go basics (Oct 29, 2014)
  • Configuration management in Go (using Viper) (Jan 14, 2017)

Cobra

• https://github.com/spf13/cobra
• Desc. : both a library for creating powerful modern CLI applications as well as a program to generate applications and command files.
• License : Apache License Version 2.0

Golang logging library

• https://github.com/op/go-logging
• implements a logging infrastructure for Go

Tools

• Static Code Analysis Tools for Go

Gocode

• https://github.com/nsf/gocode
• Desc. : An autocompletion daemon for the Go programming language
• License : MIT

Delve

• https://github.com/derekparker/delve
• Desc. : a debugger for the Go programming language.
• License : MIT

• References
  • Official documentation
  • CLI

Commands

command	description	remarks
dlv attach	Attach to running process and begin debugging
dlv exec	Execute a precompiled binary, and begin a debug session

Readings

• How to solve “ptrace operation not permitted” when trying to attach GDB to a process? (Oct 6 '13)

pprof

• https://github.com/google/pprof
• Desc. : a tool for visualization and analysis of profiling data
• License
• Written in : Go
• Sources : https://github.com/google/pprof

• Readings
• End-user documentation

C, C++

• >> On C/C++

C#

• C# Reference
• C# Programming Guide
• C# Tutorials
• C# Station Tutorial

• Interpolated Strings
• Arrays Tutorial
• C# Catching and Throwing Standard Exception Types
• Best Practices for Exceptions

• Properties
• C# Attributes Tutorial

• Func<T, TResult> Delegate
• Func<T1, T2, TResult> Delegate

• Structuring Solutions and Projects (January 2002)
• .NET project structure
• General Structure of a C# Program
• C# Coding Standards and Naming Conventions
• C# Coding Style Guide
• .NET Framework Naming Guidelines
  • Capitalization Conventions
• .NET Framework 1.1 Naming Guidelines
• C# Coding Conventions
• The Fine Art of Commenting
• Recommended Tags for Documentation Comments

• API
  • .NET Framework 4 Class Library
    • Exception Class
    • InvalidOperationException Class
    • System.Collections.Generic Namespace
    • System.Collections Namespace
    • System.ComponentModel.DataAnnotations Namespace
    • System.Data Namespace
    • System.Data.OleDb Namespace
• ADO API Reference
• ADOX API Reference

• Strings in C# and .NET
• Cleaning Up Unmanaged Resources
• Using Objects That Implement IDisposable
• How to create Microsoft Access database in C# programmatically?(Jan 24 '11)
• C# documentation generator? (Mar 13 '09)
• Collections : List, Dictionary, ArrayList, Hashtable, ConcurrentDictionary, ...
• Does C# 6.0 work for .NET 4.0? (Mar 8 '15) : Yes (mostly)

Ruby

• Ruby programming language
• RailsInstaller
  • the quickest way to go from zero to developing Ruby on Rails applications.

• RubyGems Guide/Pattern
• 'Ruby Essentials' (a free on-line book)

• API
  • Ruby 2.3.2
    • Ruby 2.3.2 Core API
    • Ruby 2.3.2 Standard Library API
  • Ruby 1.9.3 Standard Library Documentation

• Convention
  • Ruby coding style guide
  • Ruby and Rails Naming Conventions
  • RubyCodingConvention

Readings

• What is attr_accessor in Ruby? (Dec 6 '10)
• Ruby String Interpolation : #{expression}

Metaprogramming

• Metaprogramming in Ruby: It's All About the Self (15 Nov 2009)
• Self - The current/default object

Design Pattern

• Ruby Singleton Pattern

misc

• SSL CERTIFICATE UPDATES
  • to solve errors with SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed

Libraries

Rouge

• http://rouge.jneen.net/
• Desc. : An elegant, extendable code highlighter written in pure Ruby
• License : MIT license
• Sources : https://github.com/jneen/rouge

TypeScript

• http://www.typescriptlang.org/
• Desc. : a typed superset of JavaScript that compiles to plain JavaScript.
• Readings
  • Language Spec
  • Handbook

CoffeeScript

• http://coffeescript.org/
• Desc. : a little language that compiles into JavaScript.
• Sources : https://github.com/jashkenas/coffeescript

ActionScript

• http://www.adobe.com/devnet/actionscript.html
• Desc. : the programming language for the Adobe Flash Player and Adobe AIR runtime
• References
  • ActionScript 3 API Reference
    • flash.external.ExtensionContext
    • flash.events.ExtensionContext
    • flash.display.DisplayObject
    • spark.components.SkinnableContainer
  • ActionScript (Wikipedia)

• Readings
  • ActionScript tutorials and articles
  • Performance
    • Understanding Memory Leaks in ActionScript (May 7, 2008)
      • Incorrect use of EventListners are the number one cause of memory leaks in ActionScript.
  • ANE
    • Working tutorial to install AIR native extensions in Flash Develop 4

Erlang

• http://www.erlang.org/
• Desc. : a programming language used to build massively scalable soft real-time systems with requirements on high availability.

• References
  • Official documentation

• Readings
  • Bit Syntax

Haskell

• http://www.haskell.org/
• Desc. : an advanced purely-functional programming language.

Lua

• http://www.lua.org
• Desc. : a powerful, efficient, lightweight, embeddable scripting language

R

• Homepage
• The R Manuals
  • An Introduction to R
• R package documentations
  • base package
  • graphics package
  • stats package
  • utils package

• R-Fiddle

Code

• ASCII (US-ASCII, ISO646-US 128 characters)
  • ASCII control code chart
  • ASCII printable code chart
• ISO/IEC 8859-1 (ISO-8859-1, ISO-LATIN-1, 256 characters)
• Character Sets
• Windows Code Page Identifiers

• Unicode code point
  • "U+" followed by its hexadecimal number.
  • e.g. U+0058, U+E0001, U+10FFFD
• HTML numeric character reference
  • "&#" + decimal number + ";" or "&#x" + hexadecimal number + ";"
  • e.g. &#168;, &#xA8;, &#9824;, &#x2660;

ISO	Title	Description	Remarks
ISO 8601	Data elements and interchange formats	an international standard covering the exchange of date- and time-related data.

• Mathematical Symbols

Punctuation

• Punctuation(Wikipedia)
  • the use of spacing, conventional signs, and certain typographical devices as aids to the understanding and correct reading of written text, whether read silently or aloud

• Portable Character Set in Single UNIX Specification, Version 2
• ASCII Punctuation and Number Characters
• POSIX punctuation character (!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~)

Name	Symbol	HTML 4.0 Entity	Remarks
parentheses	( )		round brackets, curved brackets, oval brackets
square brakets	[ ]		brakets
braces	{ }		curly brackets, flower brackets
guillemets	« »	« »
single quotation mark	‘ ’	‘ ’
double quotation mark	“ ”	“ ”
period	.		full stop, dot, point
ellipses	…	…
question mark	?
exclamation mark	!
comma	,
colon	:
semicolon	;
dash	– —	– —
hyphen	‐
apostrophe	'
slash	/

• On dashes, hyphens, and other important aspects of life (Feb 23, 2013)

Typography

Name	Symbol	HTML 4.0 Entity	Remarks
tilde	~	˜
grave accent	`		backtick, backquote
at sign	@
number sign	#		pound sign, hash mark
percent	%
caret	^
circumflex	ˆ	ˆ
ampersand	&	&
asterisk	∗	∗	star
underscore	_		understroke
backslash	\
vertical bar	|		pipe, stick, vertical slash, thick colon
pilcrow	¶	¶	paragraph mark, paragraph sign
bullet	•	•
section sign	§	§
prime	′	′	minutes, feet
double prime	″	″	seconds, inches
therefore sign	∴	∴

Unicode

• Unicode (more than 120,000 characters)
• Universal Coded Character Set (ISO/IEC 10646)
  • positions 0 through 255 of ISO/IEC 10646 and Unicode are the same as in ISO-8859-1, alias ISO Latin 1.
  • positions 0 through 127 of ISO/IEC 10646 and Unicode are the same as in ISO/IEC 646.
  • the 128 ASCII and 256 ISO-8859-1 (Latin 1) characters are assigned Unicode/UCS code points that are the same as their codes in the earlier standards.

• Unicode and JavaScript
  • Kind explain of important unicode concepts
• Unicode Character Encoding Model
• Unicode 8.0.0(Released: 2015 June 17)

• Chart
  • General Punctuation(0x2000-0x206F)
  • Mathematical Operators(0x2200-0x22FF)

• What's the difference between a character, a code point, a glyph and a grapheme? (Dec 6 '14)

Term	Description	Remarks
Typography	the art and technique of arranging type to make written language legible, readable and appealing when displayed.
Glyph	an elemental symbol within an agreed set of symbols, intended to represent a readable character for the purposes of writing	Typography
Grapheme	the smallest functional unit of a writing system	Linguistics

Date Time

• ISO 8601
• Internet Date/Time Format
• RFC 3339 - Date and Time on the Internet: Timestamps
• RFC 5546 - Internet Calendaring and Scheduling Core Object Specification (iCalendar)

• foo must be an RFC 3339 date-time
• What's the difference between ISO 8601 and RFC 3339 Date Formats? (Feb 6 '09)

• Unix time (aka POSIX time or epoch time)

Timezone

• Coordinated Universal Time(UTC)
• Greenwich Mean Time(GMT)

• tz database
• List of tz database time zones
• The tz database home page

• List of time zone abbreviations

• Java
  • java.util.TimeZone API
  • java.time.ZoneId API
  • java.util.Date API
    • explains difference between GMT and UTC

Locale

• List of ISO 639-1 codes : a standardized nomenclature used to classify languages
• ISO 15924 : codes for the representation of names of scripts
• ISO 3166-1 : Codes for the representation of names of countries and their subdivisions – Part 1: Country codes
• ISO 3166-1 alpha-2 : two-letter country codes
• java.util.Locale API
• github.com/go-playground/locales package

Currency

• ISO 4217 Currency Code
• java.util.Currency API

Unique Identifier

Scheme	Literal Length	Format	Description	Remarks
UUID	36 characters (32 hexadecimal digits and 4 hyphens)	xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx		GUID
Snowflake ID	64 bit		41 bits : timestamp (epoch), 10 bits : machine ID, 12 bits : sequence	Twitter, Discord, Instagram

• RFC 4122 - A Universally Unique IDentifier (UUID) URN Namespace
• Announcing Snowflake (1 June 2010)

Color Space

• Color space (Wikipedia)
  • Generic color spaces
• RGB (MultimediaWiki)
• Color Formats

• java.awt.image.ColorModel API
• java.awt.color.ColorSpace API

Encoding

• Binary-to-text encoding

Encoding	Efficiency	Description	Characters	Remarks
Base64	75%	Represent binary data in an ASCII string format by translating it into a radix-64 representation.	[A-Za-z0-9], +, /	padding: =
URL Encoding		a mechanism for encoding information in a Uniform Resource Identifier (URI)	[A-Za-z0-9], -, _, ~, .	Percent Encoding

Online Encoder/Decoder

Site	Description	Remarks
Hex decoder	Online hexadecimal to text converter

Codec

• Codec(Wikipedia)
  • a device or computer program capable of encoding or decoding a digital data stream or signal.
  • coder-decoder or compressor-decompressor
• List of codecs
• javax.imageio pacakge info

• Image file type and format guide (MDN)
  • image/apng, image/avif, image/gif, image/jpeg, image/png, image/svg+xml, image/webp

Category	Format Name	Full Name	MIME Type	File Extensions	Appeared in	Developed by	Remarks
Image	PNG	Portable Network Graphics	image/png	.png	1996
	JPEG	Joint Photographic Expert Group	image/jpeg	.jpg, .jpeg	1992
	GIF	Graphics Interchange Format	image/gif	.gif	1987
	SVG	Scalable Vector Graphics	image/svg+xml	.svg	2001	W3C	Vector graphics
	WebP	Web Picture	image/webp	.webp	2010	Google
Video	[1]		video/webm, audio/webm	.webm	2010	Google

JPEG

• The Joint Photographic Experts Group
• JPEG Metadata Format Specification and Usage Notes

PNG

• Portable Network Graphics Specification and Extensions
• PNG Metadata Format Specification

GIF

• Cover Sheet for the GIF89a Specification
• GIF Metadata Format Specification

BMP

• BMP Metadata Format Specification

FLV and F4V

• Flash Video(Wikipedia)
  • a container file format used to deliver video over the Internet using Adobe Flash Player version 6 and newer.
• FLV and F4V File Format Specification

Font

• Serif
  • a small line or stroke regularly attached to the end of a larger stroke in a letter or symbol within a particular font or family of fonts.
• Sans-serif
  • French word sans, meaning "without" ...

Category	Font	Example	Foundary	Released At	Remarks
Serif	Times New Roman	ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz 0123456789 ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz 0123456789 || || 1932 ||
	Georgia	ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz 0123456789 ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz 0123456789 || Microsoft || 1996 ||
	Garamond	ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz 0123456789 ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz 0123456789 || || ||
	Baskerville	ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz 0123456789 ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz 0123456789 || || ||
Sans Serif	Arial	ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz 0123456789 ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz 0123456789 || || 1982 ||
	Helvetica	ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz 0123456789 ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz 0123456789 || || 1957 ||

• Sans Serif vs Serif Font: Which Should You Use & When?

Misc

• The Swift Codes : Swift Codes or BIC Codes for all the Banks in the world.
• ISO 9362
  • Defines a standard format of Business Identifier Codes (also known as SWIFT-BIC, BIC, SWIFT ID or SWIFT code) approved by the ISO.

• UNSPSC(United Nations Standard Products and Services Code)
  • a taxonomy of products and services for use in eCommerce
• US Airports Code

• Infinity Stones : six immensely powerful objects tied to different aspects of the universe, created by the Cosmic Entities
• Gemstone Type List

• 15 Constellations Every Man Should Know
• List of brightest stars

Control Character

• Control Character

Name	Abbreviation	Hex Value	Escape Sequence	Description	Remarks
Line Feed	LF	0x0A	\n	moves the print head down one line, or to the left edge and down	New Line
Carriage Return	CR	0x0D	\r	moves the printing position to the start of the line, allowing overprinting
Form Feed	FF	0x0C	\f	o cause a printer to eject paper to the top of the next page, or a video terminal to clear the screen	Page Break

• Newline

OS	Escape Sequence	Abbreviation	Remarks
UNIX, Linux, macOS	\n	LF
Windows	\r\n	CR LF
classic Mac OS	\r	CR

Escape Sequence

• Escape Sequence
  • a combination of characters that has a meaning other than the literal characters contained therein
• Escape Character
  • a character that invokes an alternative interpretation on the following characters in a character sequence

Language	Hex Escape	Unicode Escape	Octal Escape	Special Sequences	Remarks
Java		\uHHHH	\O \OO \OOO	\\ \' \" \b \f \n \r \t \v
JavaScript	\xHH	\uHHHH	\O \OO \OOO	\\ \' \" \b \f \n \r \t \v
Solidity	\xHH	\uHHHH		\\ \' \" \b \f \n \r \t \v

Data Format

• Comparison of data serialization formats
• Lossless compression

• Fielded Text
• TLV (Type-Length-Value)

• Schema evolution in Avro, Protocol Buffers and Thrift
• Thrift vs Protocol Buffers vs Avro - Biased Comparison (Sep 17, 2012)

JSON

• Introducing JSON
• JSON Tutorial at W3Schools
• JSON Schema Specification Draft 3

• Can I comment a JSON file?
• Converting a JSON Text to a JavaScript Object
  • The answer is No.
• JSON configuration file format(2011/05/08)
• Comparison of Protobuff, Thrift, Avro, etc (27 May 2011)

JSON5

• a superset of JSON that aims to alleviate some of the limitations of JSON by expanding its syntax to include some productions from ECMAScript 5.1
• JSON5 : JSON for Humans

JSON Path

• JSONPath - XPath for JSON

JSON Pointer

• RFC 6901 : JSON Pointer

JSON-LD

• JSON for Linking Data
• JSON-LD (Wikipedia)

JSON Schema

• The home of JSON Schema
• JSON Schema/GitHub

• Specifications
  • JSON Schema Core Spec
  • JSOn Schema Validation Spec
  • Relative JSON Pointers Spec

• Built-in Types and Facets

Type	Description	Facets	Remarks
number		enum, multipleOf, maximum, exclusiveMaximum, minimum, exclusiveMinimum
string	a sequence of zero or more Unicode characters, wrapped in double quotes, using backslash escapes	enum, maxLength, minLength, pattern
array	an ordered collection of values	maxItems, minItems, uniqueItems, maxContains, minContains	[ ]

• Built-in Formats

Name	Type	Format	Description	Remarks
Datetime	string	date-time	date time	date-time in RFC-3339
Date	string	date	yyyy-MM-dd	full-date in RFC-3339
Time	string	time	HH:mm:ss[.S](Z|(+|-)m′m′:s′s′)	full-time in RFC-3339
Duration	string	duration		ISO-8601
eMail Address	string	email		RFC-5321
IDNA eMail Address	string	idn-email		RFC-6531
Hostname	string	hostname		RFC-1123
IDNA Hostname	string	idn-hostname		RFC-5890
IP Version 4 Address	string	ipv4		RFC-2673
IP Version 6 Address	string	ipv6		RFC-4291
URI	string	uri		RFC-3986
URI Reference	string	uri-reference		RFC-3986
IRI	string	iri		RFC-3987
IRI Reference	string	iri-reference		RFC-3987
UUID	string	uuid		RFC-4122
URI Template	string	uri-template		RFC-6570
Regular Expression	string	regex		JSON Schema/Regular Expression

• JSON Schema Implementations
• Internet-Draft : JSON Schema: core definitions and terminology : defines the media type "application/schema+json"
• Internet-Draft : JSON Reference
• Understanding JSON Schema
• JSON Schema Schema
• JSON Schema Store : A collection of JSON schemas

• JSON - Schema
• JSON Schema: specifying and validating JSON data structures
• Validating JSON with Schemas
• Recursive entity representation in JSON schema

JMESPath

• http://jmespath.org/
• Desc. : a query language for JSON
• Sources : https://github.com/jmespath

References

• JMESPath Specification
  • MultiSelect List
• JMESPath Tutorial
• Azure CLI 2.0 JMESPath
  • Navigating, Projecting, Filtering, Merging, Flattening,

Readings

• Filter output based on the existence of multiple key/value pairs (Jan 6 '17)
  • Nested filters : [?children[?@.grandson=='Tom']]

YAML

References

• YAML on Wikipedia
• The official YAML web site
• YAML 1.2 Specification
• Language-Independent Types for YAML Version 1.1
  • !!map !!omap !!pairs !!set !!seq !!binary !!bool !!float !!int !!merge !!null !!str !!timestamp !!value !!yaml
• The YAML Format
  • Strings : single-quoted string, double-quoted string, unquoted string
• Learn X in Y minutes Where X=yaml

• YAML - Anchors, References, Extend (21 Feb 2016)
• YAML Multiline
  • |, |-, |+, |-2, >, >-, >+, >+2
• Merge Key Language-Independent Type for YAML Version 1.1

Readings

• Can I concatenate aliases in YAML? (Sep 27 '16)
  • No you cannot do that, an alias replaces a complete node.

Tips and Tricks

Abbreviated form of dictionaries and lists

martin: {name: Martin D'vloper, job: Developer, skill: Elite}
fruits: ['Apple', 'Orange', 'Strawberry', 'Mango']

Protocol Buffers

• Protocol Buffers - Google's data interchange format
• Protocol Buffers homepage
  • a language-neutral, platform-neutral extensible mechanism for serializing structured data.

HOCON

• HOCON – Informal Specification

• HOCON Java API

TOML

• TOML : Tom's Obvious, Minimal Language
• TOML (on Wikipedia)
• TOML Wiki

HCL

• HCL (HashiCorp Configuration Language)
  • a configuration language built by HashiCorp.
• HCL Native Syntax Specification
• Terraform Configuration Syntax

Markup

• MediaWiki
• Markdown
• MultiMarkdown
  • a tool to help turn minimally marked-up plain text into well formatted documents, including HTML, PDF (by way of LaTeX), OPML, or OpenDocument (specifically, Flat OpenDocument or ‘.fodt’, which can in turn be converted into RTF, Microsoft Word, or virtually any other word-processing format).
• AsciiDoc
  • a text document format for writing notes, documentation, articles, books, ebooks, slideshows, web pages, man pages and blogs.

• Comparison of wiki hosting services
• Lightweight markup conversion using Eclipse WikiText.
  WikiText provides Ant tasks to convert markups to HTML, DocBook, Eclipse help or XSL-FO
• Restarting Redmine without restarting Apache
• Technical Writing in a Wiki -- Single Source Publishing

• CSV Converter
  • allows you to enter a table in CSV-format and convert it to HTML or the WikiMedia format for tables.

MediaWiki Markup

• Markup spec
• Help Contents
• Help:Editing
  • Help:Formatting
  • Help:Links
  • Help:List
  • Help:Images
  • Help:Tables
  • Help:Table
  • Help:Templates
  • Help:Formula
  • Extension:Math/Help:Formula

• Manual:Interface/Stylesheets
• Template Repository

• Diagrams
  • Dia, Ditta, GraphViz, Mermaid, PlantUML

• Built-in classes for table

Class	Description	Remarks
wikitable	Basic styling (light gray background, borders, padding and align left)
sortable	Makes the table rows sortable by the selected/clicked header cell
mw-collapsible	Adds a link to collapse the table	collapsible
mw-collapsed	Makes table to default to collapsed state	collapsed
mw-datatable	Allows for row highlighting

• Configuration Settings

Magic Words

• Help:Magic words
  • Behavior switches
  • Variables
  • Parser functions

Behavior Switches	Description	Remarks
__TOC__	Places a table of contents at the word's current position

Variable	Description	Remarks
{{CURRENTYEAR}}	Current Year

Function	Description	Remarks
{{formatnum:unformatted number}}	Takes an unformatted number and outputs it in the localized digit script and formatted with decimal and decimal group separators, according to the wiki's default locale.

Extensions

Extension	Description	Remarks
Extension:SyntaxHighlight	Provides rich formatting of source code using the <syntaxhighlight> tag.	Powered by the Pygments library
Extension:Header Tabs	Transforms top-level MediaWiki headers into tabs using the jQuery UI JavaScript library.
Extension:Math	Provides support for rendering mathematical formulae.

Extension:SyntaxHighlight

• Parameters

Parameter	Description	Remark
lang	defines what lexer should be used	supported languages
line	enables line numbers
start	defines the first line number of the code block
highlight	specifies one or more lines that should be marked
inline	indicates that the source code should be inline as part of a paragraph
class
style	allows CSS attributes to be included directly

Real-world Examples

• MediaWiki:Common.css
• Category:Templates

Markdown

• Markdown Syntax
• SourceForge Markdown Syntax Guide
• Markdown Basic Syntax
• Markdown Extended Syntax
• Markdown tutorial at CommonMark
• Markdown quick reference
• Mastering Markdown
• Markdown Cheatsheet

• CommonMark Spec

• Are numbered headings in Markdown / Rdiscount possible? (Nov 15 '13)
• Is it possible to add border to image in GitHub markdown? (May 20 '16)

| ![Alt name of image](/path-to-image.png) |
| ------ |

GitHub Flavored Markdown

• GitHub Flavored Markdown Spec

• GitHub Flavored Markdown
  • Basic writing and formatting syntax
  • Organizing information with tables
  • Creating and highlighting code blocks
• All Languages known to GitHub

• Working with Tables in GitHub Markdown (Nov 21, 2019)
• "Dropdowns" in Markdown : <details>
• How can I wrap my markdown in an HTML div? (Mar 31 2015)

kramdown

• https://kramdown.gettalong.org
• Desc. : a library for converting text written in a superset of Markdown to HTML
• License :

Readings

• kramdown Documentation
• kramdown Quick Reference
• Kramdown Syntax

AsciiDoc

a lightweight and semantic markup language primarily designed for writing technical documentation.

• AsciiDoc Language Documentation

reStructuredText

• reStructuredText
• A ReStructuredText Primer

Textile

• TxStyle · Textile Documentation
  • An overview of the Textile syntax
• Official reference manual for Textile 2
• Online form for trying out Textile 2 syntax
• Original Textile
• Textile Reference
• Textile Reference Manual for RedCloth 4

LaTeX

• LaTeX
• LaTeX Base : Free online LaTeX WYSWYG editor

• LaTeX Basics
• List of LaTeX Environments
• LaTeX Command Glossary
• LaTeX Line and Page Breaking
• LaTeX Fonts

• Math Mode
  • There are a few ways to enter math mode, however the most common is $....$, where the text within the dollar signs is in the math mode environment. You have already been using math mode unknowingly by using the \begin{equation} and \end{equation} commands.
• LaTeX Mathematics
• LaTeX Mathematical Symbols
• LaTeX Symbols
• LaTeX Advanced Mathematics

Element	Description	Syntax/Sample	Remarks
environments		\begin{environmentname} text to be influenced \end{environmentname}	document, math
commands		\commandname[option1,option2,...]{argument1}{argument2}...

Commands

Category	Command	Description	Remarks
Whitespaces	\quad	space equal to the current font size (= 18 mu)
	\,	3/18 of \quad (= 3 mu)
	\:	4/18 of \quad (= 4 mu)
	\;	5/18 of \quad (= 5 mu)
	\!	-3/18 of \quad (= -3 mu)
	\qquad	twice of \quad (= 36 mu)
	\\	new line
	\\~\\	double new line
Text	\text{...}
	\textrm{...}	roman font family
	\textsf{...}	sans serif font family
	\texttt{...}	teletypefont family	fixed-width or monospace font
Letters	\Alpha, \alpha	Α, α	Greek letter alpha
	\Beta, \beta	Β, β	Greek letter beta
Operators	\equiv	≡	equivalent to

Sample LaTex Codes

Code	Display	Remarks
L_{s}(T) \equiv (T_{n}, T_{p}, T_{t}, T_{v}, p, \beta, (), ())	$L_{s}(T)\equiv (T_{n},T_{p},T_{t},T_{v},p,\beta ,(),())$	three line equivalent operator
p \equiv \begin{cases}T_{i} & \text{ } T_{t} = 0 \\ T_{d} & \text{ otherwise} \end{cases}	$p\equiv {\begin{cases}T_{i}&{\text{ }}T_{t}=0\\T_{d}&{\text{ otherwise}}\end{cases}}$	cases (\begin{cases} ... \end{cases})
(T_{w}, T_{r}, T_{s}) \equiv \texttt{ECDSASIGN}(h(T), p_{r})	$(T_{w},T_{r},T_{s})\equiv {\texttt {ECDSASIGN}}(h(T),p_{r})$	teletype text (\texttt)
y^2 = x^3 + ax + b \; (\texttt{mod} \; p)	$y^{2}=x^{3}+ax+b\;({\texttt {mod}}\;p)$	space (\;)

Simple equation with fraction

• https://math.embed.fun/hP7SJSqPFQXCt9mRHemvJd

\begin{equation}
\\
difficulty = \frac{2^{256}}{target}

\\~\\

\frac{1}{difficulty} = \frac{target}{2^{256}} = mining \ probability
\\
\end{equation}

Multimedia

• Display Resolution
• Graphics Display Resolution

Name	Width	Height	Aspect Ratio	Remarks
VGA	640	480	4:3	Video Graphics Array
SVGA	800	600	4:3	Super VGA
HD	1280	720	16:9	High-Definition
FHD	1920	1080	16:9	Full HD
QHD	2560	1440	16:9	Quad HD (22 x HD)
4K UHD	3840	2160	16:9	Ultra HD (32 x HD, 22 x FHD), 4K
8K UHD	7680	4320	16:9	8K

Video

• Video compression picture types (Wikipedia)
  • I-frame, P-frame, B-frame
• H.264/MPEG-4 AVC

• Internet Connection Speed Recommendations
  • SD : 3.0Mbps, HD : 5.0Mbps, UHD : 25Mbps
• What is the bandwidth requirement to stream a 1080p HD movie off a remote server? (Oct 20, 2013)

Disk Image

• Disk Image
• Comparison of disc image software

Format	Extension	Description	Supported By	Remarsk
ISO	.iso, udf	an archive file that contains everything that would be written to an optical disc, sector by sector, including the optical disc file system.
Media Descriptor File	.mdf, .mds	a proprietary disc image file format developed for Alcohol 120%	Daemon Tools, CDemu, MagicISO, PowerDVD, WinCDEmu	support Mixed Mode CD
IMG	.img	store raw disk images of floppy disks, hard drives, and optical discs or a vector image.
CUE Sheet	.cue	a metadata file which describes how the tracks of a CD or DVD[citation needed] are laid out.		support Mixed Mode CD
CloneCD Control File	.ccd	a text descriptor with the extension .ccd used by CloneCD to mark the properties of a CD/DVD image.		support Mixed Mode CD

Program	Can Burn	Can Mount	Input Format	Output Format	OS
CDBurnerXP	Yes	No		ISO, MDF	Windows
ImgBurn	Yes	No		ISO, IMG, CUE	Windows
Virtual CloneDrive	No	Yes	ISO, BIN, IMG, UDF, DVD, CCD		Windows
WinCDEmu	No	Yes	ISO, BIN, IMG, MDF, CCD, NRG		Windows

---

Networking

• Cisco DocWiki
• Internetworking Technology Handbook
• Network Security Technologies and Solutions (Google eBook)

• The Difference Between a Router, Switch and Hub (November 17, 2006)
• Hub vs. Switch

• Multiplexing
• Same-origin policy
• Cross-Origin Resource Sharing (CORS)

Procotol	Full Name	Description	Layer	Remarks
ARP	Address Resolution Protocol	a communication protocol used for discovering the link layer address, such as a MAC address, associated with a given internet layer address, typically an IPv4 address.	Link	IPv4 over IEEE 802.3 and IEEE 802.11
ICMP	Internet Control Message Protocol	used by network devices, including routers, to send error messages and operational information indicating, for example, that a requested service is not available or that a host or router could not be reached.	Internet
BGP	Border Gateway Protocol	a standardized exterior gateway protocol designed to exchange routing and reachability information among autonomous systems (AS) on the Internet	Application
SNMP	Simple Network Management Protocol	an Internet Standard protocol for collecting and organizing information about managed devices on IP networks and for modifying that information to change device behavior.	Application
MQTT	Message Queuing Telemetry Transport	an ISO standard publish-subscribe-based messaging protocol.	Application	ISO/IEC PRF 20922

• systemd’s Predictable Network Interface Names
  • udev/udev-builtin-net_id.c

Name Pattern	Description	Remarks
eno1	On-board device with Firmware/BIOS provided index number
ens1	Off-board device with Firmware/BIOS provided PCI Express hotplug slot index number
enp2s0	Device with physical/geographical location of the connector of the hardware
enx78e7d1ea46da	Device with the interfaces's MAC address
eth0	Classic, unpredictable kernel-native ethX naming

• Networking Devices

Device	Description	Remarks
Router	a networking device that forwards data packets between computer networks.

• Network Device Icons

---

TCP/IP

Fundamentals

• TCP Connection establishment
  • a three-way handshake : SYN, SYN-ACK, ACK
• TCP Connection termination
  • a four-way handshake : FIN, ACK, FIN, ACK
• TCP/IP Fundamentals for Windows (TechNet, November 02, 2004)
• Buckets of Sockets
  • UDP Sockets, TCP Sockets, Sockserv

• Classless Inter-Domain Routing(CIDR)
  • a method for allocating IP addresses and IP routing
  • IP address = most significant bits + least significant set
  • most significant bits : the network prefix, a whole network or subnet identifier
  • least significant set : the host identifier

• Private IPv4 Addresses

classful name	IP address range	# of addresses	subnet mask	host id size	mask bits	RFC1918 name
single class A network	10.0.0.0 – 10.255.255.255	16,777,216	255.0.0.0	24 bits	8 bits	24-bit block
16 contiguous class B networks	172.16.0.0 – 172.31.255.255	1,048,576	255.240.0.0	20 bits	12 bits	20-bit block
256 contiguous class C networks	192.168.0.0 – 192.168.255.255	65,536	255.255.0.0	16 bits	16 bits

• Priviliged ports
  • The TCP/IP port numbers below 1024 are special in that normal users are not allowed to run servers on them

• List of TCP and UDP port numbers
  • Well-known ports and Registered ports

• Ephemeral port
  • a short-lived transport protocol port for Internet Protocol (IP) communications.
  • IANA : 49152 to 65535
  • Linux : 32768 to 61000 (/proc/sys/net/ipv4/ip_local_port_range)

TCP Socket Options

Option	Description	Remarks
TCP_USER_TIMEOUT	When the value is greater than 0, it specifies the maximum amount of time in milliseconds that transmitted data may remain unacknowledged before TCP will forcibly close the corresponding connection and return ETIMEDOUT to the application. If the option value is specified as 0, TCP will use the system default.

TCP States

• TCP State Diagram

                   CLOSED
		            |  |
                    |  |
	      	       LISTEN
 	                |  |
 SYN RECEIVED ------+  +-------- SYN SENT
     |                               |
     +--------- ESTABLISHED ---------+
                    |  |
     +--------------+  +-------------+
     |                               |
     |                               |
 FIN WAIT 1 ------ CLOSING      CLOSE WAIT
     |                |              |
     |                |              |
 FIN WAIT 2 ----- TIME WAIT	     LAST ACT
                      |              |
                      |              |
                    CLOSED ----------+

Readings

• Coping with the TCP TIME-WAIT state on busy Linux servers (February 24, 2014)
• TIME_WAIT and its design implications for protocols and scalable client server systems (January 21, 2011)

• When is a TCP connection considered idle?
  • TCP_USER_TIMEOUT : The maximum amount of time in milliseconds that transmitted data may remain unacknowledged before TCP will forcibly close connection.
• RFC5482 - TCP User Timeout Option
• TCP_USER_TIMEOUT (Aug. 28, 2010)
  • a new socket option to specify max timeout before a TCP connection is aborted

---

DNS

• Domain Name System (on Wikipedia)
• List of DNS record types (on Wikipedia)

• Differences Among A, CNAME, ALIAS, and URL records

Type	Description	Remarks
A record	maps a name to one or more IP addresses
CNAME record	maps a name to another name
ALIAS record	maps a name to another name, but can coexist with other records on that name
URL record	redirects the name to the target name using the HTTP 301 status code

---

LAN

• Link bonding across multiple switches? (Jul 11 '12)

---

HTTP

RFC	Title	Description	Remarks
RFC-2616	Hypertext Transfer Protocol -- HTTP/1.1
RFC-7235	Hypertext Transfer Protocol (HTTP/1.1): Authentication
RFC-7239	RFC 7239 Forwarded HTTP Extension

Status Codes

• HTTP/1.1 Status Code Definitions
• List of HTTP status codes

Code	Description	Remarks
400 Bad Request	The server cannot or will not process the request due to an apparent client error
401 Unauthorized	Similar to 403 Forbidden, but specifically for use when authentication is required and has failed or has not yet been provided.	Unauthenticated
403 Forbidden	The request was valid, but the server is refusing action.	Unauthorized
404 Not Found	The requested resource could not be found but may be available in the future.
407 Proxy Authentication Required	The client must first authenticate itself with the proxy.

Header Fields

• List of HTTP header fields (on Wikipedia)
• HTTP headers (on MDN)
• Request Header Fields
• Response Header Fields
• General Header Fields
• Entity Header Fields

• HTTP Request IDs: X-Request-ID

General Header Fields

• Header fields which have general applicability for both request and response messages, but which do not apply to the entity being transferred.

Header	Description	Remarks
Connection: keep-alive|close	Controls whether or not the network connection stays open after the current transaction finishes.

Request Header Fields

Header	Description	Remarks
Authorization: type credentials	Contains the credentials to authenticate a user agent with a server, usually after the server has responded with a 401 Unauthorized status and the WWW-Authenticate header.
Proxy-Authorization: type credentials	Contains the credentials to authenticate a user agent to a proxy server, usually after the server has responded with a 407 Proxy Authentication Required status and the Proxy-Authenticate header.
Origin: scheme://hostname:port	Initiates a request for cross-origin resource sharing (asks server for Access-Control-* response fields).	CORS
Host: host:port	The domain name of the server (for virtual hosting), and (optionally) the TCP port number on which the server is listening.
Forwarded: by=identifier;for=identifier;host=host;proto=http|https	Contains information from the client-facing side of proxy servers that is altered or lost when a proxy is involved in the path of the request.	X-Forwarded-For, X-Forwarded-Host
X-Forwarded-For: client, proxy1, proxy2	A de-facto standard header for identifying the originating IP address of a client connecting to a web server through an HTTP proxy or a load balancer.	XFF
X-Forwarded-Host: host	A de-facto standard header for identifying the original host requested by the client in the Host HTTP request header.	XFH
X-Forwarded-Proto: protocol	a de-facto standard header for identifying the protocol (HTTP or HTTPS) that a client used to connect to your proxy or load balancer.	XFP
X-Request-ID	Correlates HTTP requests between a client and server.

Response Header Fields

Header	Description	Remarks
WWW-Authenticate: type realm=realm	Defines the authentication method that should be used to gain access to a resource.	Basic, Digest, OAuth, HOBA
Proxy-Authenticate: type realm=realm	Defines the authentication method that should be used to gain access to a resource behind a proxy server.
Access-Control-Allow-Credentials: true	Tells browsers whether to expose the response to frontend JavaScript code when the request's credentials mode (Request.credentials) is "include".	CORS
Access-Control-Allow-Origin: *|origin|null	Indicates whether the response can be shared with requesting code from the given origin.	CORS
Access-Control-Allow-Methods: method, method, ...	Specifies the method or methods allowed when accessing the resource in response to a preflight request.	CORS
Access-Control-Allow-Headers: header-name, header-name, ...	Indicate which HTTP headers can be used during the actual request.	CORS
Access-Control-Max-Age: delta-seconds	Indicates how long the results of a preflight request can be cached.	CORS
Content-Security-Policy: policy-directive; policy-directive	allows web site administrators to control resources the user agent is allowed to load for a given page.	CSP

Mechanisms

• HTTP Authentication

Mechanism	Description	Related	Remark
Authentication	HTTP provides a general framework for access control and authentication.	Authorization, Proxy-Authorization
Cross-Origin Resource Sharing (CORS)	a mechanism that uses additional HTTP headers to tell browsers to give a web application running at one origin, access to selected resources from a different origin.	Origin, Access-Control-Allow-Origin
Content Security Policy (CSP)	an added layer of security that helps to detect and mitigate certain types of attacks, including Cross Site Scripting (XSS) and data injection attacks.	Content-Security-Policy

• MIME (Multipurpose Internet Mail Extensions)
  • an Internet standard that extends the format of email messages to support text in character sets other than ASCII, as well as attachments of audio, video, images, and application programs.

Category	Type	Description	Remarks
Application	application/x-www-form-urlencoded		Percent encoding
Multipart	multipart/form-data	Used to express values submitted through a form	HTML 4.0

---

HTTP/2

• HTTP/2 Complete Tutorial
• What is Multiplexing in HTTP/2?

---

WebSocket

• WebSocket (on Wikipedia)
  • a computer communications protocol, providing full-duplex communication channels over a single TCP connection

• Inspecting WebSocket Traffic with Chrome Developer Tools (May 1, 2017)
• WebSocket testing (July 21, 2016)

---

SMTP

• RFC 5321 - Simple Mail Transfer Protocol

• DomainKeys Identified Mail(DKIM)
  • an email authentication method designed to detect forged sender addresses in emails (email spoofing), a technique often used in phishing and email spam.
  • allows the receiver to check that an email claimed to have come from a specific domain was indeed authorized by the owner of that domain.

• https://stackoverflow.com/questions/386294/what-is-the-maximum-length-of-a-valid-email-address (Dec 22 '08)

---

SNMP

• Simple Network Management Protocol: an Internet Standard protocol for collecting and organizing information about managed devices on IP networks and for modifying that information to change device behavior.

• Simple Network Management Protocol (on Wikipedia)

---

MQTT

• Message Queuing Telemetry Transport : an ISO standard (ISO/IEC PRF 20922) publish-subscribe-based messaging protocol.

• MQTT (on Wikipedia)

---

RTSP

• Real Time Streaming Protocol
• RTSP (Wikipedia)
• RTSP (MultimediaWiki)

• OpenCV - how to capture rtsp video stream(Jan 10 '14)
• io.netty.handler.codec.rtsp pacakge

---

RTMP

• Real Time Messaging Protocol
• RTMP Specification
• RTMP (Wikipedia)
• Flash Video Structure
• RTMP (MultimediaWiki)
• RTMP packet header and packet types

• org.red5.codec.VideoCodec.java
• Javacv: Decoding H.264 “live” stream coming from red5 server on android device (Mar 19 '14)

---

JSON-RPC

• a stateless, light-weight remote procedure call (RPC) protocol.
• JSON-RPC 2.0 Specification
• JSON-RPC (on Wikipedia)

• REST vs JSON-RPC (Feb 24 '13)
• Is it time to replace REST with RPC? (Sep 28, 2017)
• Discontinuing support for JSON-RPC and Global HTTP Batch Endpoints (March 22, 2018, Google Cloud Platform team)

---

gRPC

• an open source remote procedure call (RPC) system initially developed at Google.
• https://www.grpc.io/

---

Security

• Key concepts of information security : Confidentiality, Integrity, Availability, (and Non-repudiation)
• Password policy
• Kerckhoffs's principle
  • A cryptosystem should be secure even if everything about the system, except the key, is public knowledge

• Tozny Security Guides
• Best cryptography book for beginners to ensure information security (03-23-2018)
• Common Vulnerabilities and Exposures (CVE)
  • a list of entries—each containing an identification number, a description, and at least one public reference—for publicly known cybersecurity vulnerabilities.

• The best way to completely wipe your Android device (July 8, 2014)
• How To Securely Erase Your SSD Without Destroying It (April 11, 2014)

Glossary

Category	Term	Description	Remarks
Attack	Vulnerability	a weakness which can be exploited by a Threat Actor, such as an attacker, to perform unauthorised actions within a computer system	at Longman
	Eavesdropping	secretly or steathily listening to the private conversation of others without their consent	at Longman
	Session hijacking	the exploitation of a valid computer session—sometimes also called a session key—to gain unauthorized access to information or services in a computer system
	Man-in-the-middle attack	an attack where the attacker secretly relays and possibly alters the communication between two parties who believe they are directly communicating with each other
	Rainbow table	a precomputed table for reversing cryptographic hash functions, usually for cracking password hashes.
	Phishing	the fraudulent attempt to obtain sensitive information such as usernames, passwords and credit card details by disguising oneself as a trustworthy entity in an electronic communication.	fake website, social engineering
	Scam	an attempt to defraud a person or group after first gaining their confidence, used in the classical sense of trust.
	Sybil Attack	the attacker subverts the reputation system of a network service by creating a large number of pseudonymous identities and uses them to gain a disproportionately large influence.
	Attack Vector	a specific path, method, or scenario that can be exploited to break into an IT system, thus compromising its security.	often, a multi-step process
Defense	Cipher	an algorithm for performing encryption or decryption
	Key stretching	techniques used to make a possibly weak key, typically a password or passphrase, more secure against a brute-force attack by increasing the resources (time and possibly space) it takes to test each possible key.	PBKDF2, bcrypt, scrypt, Argon2
	Credential	an attestation of qualification, competence, or authority issued to an individual by a third party with a relevant or de facto authority or assumed competence to do so.	diplomas, academic degrees, certifications, identification documents, badges, passwords, keys, ...
	MAC(Message Authentication Code)	a short piece of information used to authenticate a message—in other words, to confirm that the message came from the stated sender (its authenticity) and has not been changed.	MACs differ from digital signatures as MAC values are both generated and verified using the same secret key.
	Tamperproofing	a methodology used to hinder, deter or detect unauthorised access to a device or circumvention of a security system.	misnomer
Cryptography	Homomorphic Encryption	a form of encryption that permits users to perform computations on its encrypted data without first decrypting it.
	White-Box Cryptography	combines methods of encryption and obfuscation to embed secret keys within application code.
	Multi-Party Computation (MPC)	a subfield of cryptography with the goal of creating methods for parties to jointly compute a function over their inputs while keeping those inputs private.

Concepts

• Digital Signature
• Digital Signature Algorithm (DSA)
• Elliptic Curve Digital Signature Algorithm (ECDSA)
• Digital Certificate
• Public Key Infrastructure (PKI)

A digital signature is a mathematical scheme for verifying the authenticity of digital messages or documents. A valid digital signature, where the prerequisites are satisfied, gives a recipient very strong reason to believe that the message was created by a known sender (authentication), and that the message was not altered in transit (integrity)
A key generation algorithm that selects a private key uniformly at random from a set of possible private keys. The algorithm outputs the private key and a corresponding public key.
A signing algorithm that, given a message and a private key, produces a signature.
A signature verifying algorithm that, given the message, public key and signature, either accepts or rejects the message's claim to authenticity.

The DSA algorithm involves four operations: key generation (which creates the key pair), key distribution, signing and signature verification.

The Elliptic Curve Digital Signature Algorithm (ECDSA) offers a variant of the Digital Signature Algorithm (DSA) which uses elliptic curve cryptography.

A public key certificate, also known as a digital certificate or identity certificate, is an electronic document used to prove the ownership of a public key.

A public key infrastructure (PKI) is a set of roles, policies, hardware, software and procedures needed to create, manage, distribute, use, store and revoke digital certificates and manage public-key encryption.

Standards

standard	description	remarks
Rainbow Series	a series of computer security standards and guidelines published by the United States government in the 1980s and 1990s
Trusted Computer System Evaluation Criteria (TCSEC)	a United States Government Department of Defense (DoD) standard that sets basic requirements for assessing the effectiveness of computer security controls built into a computer system	Orange Book
Common Criteria(CC)	an international standard (ISO/IEC 15408) for computer security certification	Common Criteria for Information Technology Security Evaluation
FIPS 140-2	Security Requirements for Cryptographic Modules
X.500	a series of computer networking standards covering electronic directory services
X.509	a standard that defines the format of public key certificates

Standard Algorithm Names

• Java Security Standard Algorithm Names

• Cipher Algorithm Names

Cipher Algorithm	Description	Spec	Remark
AES	a 128-bit block cipher supporting keys of 128, 192, and 256 bits.	FIPS 197	AES_128, AES_192, AES_256
DES	a symmetric-key algorithm for the encryption of digital data.	FIPS PUB 46-3
Blowfish	a symmetric-key block cipher, designed in 1993 by Bruce Schneier

• Cipher Algorithm Modes

• Cipher Algorithm Paddings

• Key Generator Algorithm

• Key Pair Generator Algorithm

Algorithm	Description	Remarks
DiffieHellman	Generates keypairs for the Diffie-Hellman KeyAgreement algorithm.
DSA	Generates keypairs for the Digital Signature Algorithm.
RSA	Generates keypairs for the RSA algorithm (Signature/Cipher).
EC	Generates keypairs for the Elliptic Curve algorithm.

• MAC Algorithms

• Message Digest Algorithms

• Signature Algorithms
  • <digest>with<encryption>

Algorithms	Description	Spec	Remarks
NONEwithRSA	Does not use a digesting algorithm before performing the RSA operation	PKCS #1
MD2withRSA	Uses the MD2 digest algorithm and RSA to create and verify RSA digital signatures	PKCS #1
MD5withRSA	Uses the MD5 digest algorithm and RSA to create and verify RSA digital signatures	PKCS #1

Fundamentals

Hashing

• Hash function
• Cryptographic hash function
• What are cryptographic hash functions?
  • Non-reversible, Diffused, Collision resistant, Deterministic, Unpredictable
• Hash function security summary
  • MD5, SHA-1, SHA256, SHA512
• Comparison of cryptographic hash functions

• Salt
  • Random data that is used as an additional input to a one-way function that hashes data, a password or passphrase.
• How to store salt?

Access Control

• Discretionary access control (DAC)
• Mandatory access control (MAC)

Misc

• CAPTCHA (Completely Automated Public Turing Test to tell Computers and Humans Apart)
  • a type of challenge–response test used in computing to determine whether or not the user is human.

• Id token Vs access token (Jul 1, 2018)

Cryptography

• Handbook of Applied Cryptography (Alfred J. Menezes, Paul C. van Oorschot and Scott A. Vanstone)

Type	Algorithm	Description	Published In	Designers	Remarks
Symmetric Key Cryptography	DES	a symmetric-key algorithm for the encryption of digital data	1975	IBM
	Triple DES	a symmetric-key block cipher, which applies the DES cipher algorithm three times to each data block.	1995
	Blowfish	a symmetric-key block cipher	1993	Bruce Schneier
	AES	a specification for the encryption of electronic data established by the U.S. NIST in 2001	1998
Public Key Cryptogrpahy	Diffie–Hellman Key Exchange	a method of securely exchanging cryptographic keys over a public channel and was one of the first public-key protocols as conceived by Ralph Merkle and named after Whitfield Diffie and Martin Hellman.	1976	Whitfield Diffie, Martin Hellman
	DSA	a Federal Information Processing Standard for digital signatures, based on the mathematical concept of modular exponentiation and the discrete logarithm problem.	1991		Key Generation, Signing, Verifying
	RSA	a public-key cryptosystem that is widely used for secure data transmission.	1977	Ron Rivest, Adi Shamir, Leonard Adleman	Key Generation, Encryption, Decryption, Signing Message
	ECDSA (Elliptic Curve DSA)	offers a variant of the DSA which uses elliptic curve cryptography.
	EdDSA (Edwards-curve EdDSA)	a digital signature scheme using a variant of Schnorr signature based on twisted Edwards curves	2011

Fundamentals

• Cryptographic Concepts

• Cryptography
  • about constructing and analyzing protocols that prevent third parties or the public from reading private messages
• Cryptosystem
  • a suite of cryptographic algorithms needed to implement a particular security service, most commonly for achieving confidentiality (encryption)
  • key generation algorithm + encryption algorithm + decryption algorithm
• Cipher(Cypher)
  • an algorithm for performing encryption or decryption
• Block cipher mode of operation
  • ECB, CBC, PCBC, CFB, OFB, ...

• Digital Signature Algorithm (DSA)
  • a Federal Information Processing Standard for digital signatures.
• Elliptic Curve Digital Signature Algorithm (ECDSA)
  • offers a variant of the Digital Signature Algorithm (DSA) which uses elliptic curve cryptography.

PKCS

• Public Key Cryptography Standards : a group of public-key cryptography standards devised and published by RSA Security Inc
• PKCS (on Wikipedia)

Standard	Name	Description	Remarks
PKCS #3	Diffie–Hellman Key Agreement Standard	A cryptographic protocol that allows two parties that have no prior knowledge of each other to jointly establish a shared secret key over an insecure communications channel.
PKCS #5	Password-based Encryption Standard		RFC 8018, PBKDF2
PKCS #6	Extended-Certificate Syntax Standard	defines extensions to the old v1 X.509 certificate specification.	Obsoleted
PKCS #8	Private-Key Information Syntax Standard	a standard syntax for storing private key information.
PKCS #11	Cryptographic Token Interface	defining a generic interface to cryptographic tokens	Cryptoki
PKCS #12	Personal Information Exchange Syntax Standard	defines an archive file format for storing many cryptography objects as a single file

PKCS#11

• OASIS PKCS 11 Technical Committee
• PKCS#11 Standard C Header Files
• PKCS11

SHA

• Secure Hash Algorithms
• SHA-1
• SHA-2 : SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, SHA-512/256
• SHA-3 : SHA3-224, SHA3-256, SHA3-384, SHA3-512, ...

Algorithm	Output Size (bits)	Born In	Remarks
MD5	128	1992
SHA-0	160	1993
SHA-1	160	1995
SHA-256	256	2001	SHA-2
SHA-512	256	2001	SHA-2
SHA3-256	256	2015
SHA3-512	512	2015

• Announcing the first SHA1 collision (February 23, 2017)
  • Today, more than 20 years after of SHA-1 was first introduced, we are announcing the first practical technique for generating a collision.

Implementations

Category	Implementation	Remarks
Java	java.security.MessageDigest class	JDK
	org.apache.commons.codec.digest.Sha2Crypt class	Apache Commons static String sha256Crypt(byte[] keyBytes, String salt) static String sha512Crypt(byte[] keyBytes, String salt)
Python 2.x	hashlib module	md5(), sha1(), sha224(), sha256(), sha384(), sha512()
Python 3.x	hashlib module	md5(), sha1(), sha224(), sha256(), sha384(), sha512(), ...
Node.js	crypto.Hash class	sha256, sha512
MySQL	SHA1() function SHA2() function

Code Snippet

• Python 2.x

>>> # Hash 'Hello, World!' with SHA-256 into hex representation
>>> import hashlib
>>> s = hashlib.sha256()
>>> s.update("Hello, World!")
>>> s.hexdigest()

• JavaScript / Node.js

> // Hash 'Hello, World!' with SHA-256 into hex representation
> crypto.createHash('sha256').update('Hello, World!').digest('hex');

PEM

• Privacy-enhanced Electronic Mail (on Wikipedia)

Digital Signature

• Digital signature scheme

Element	Description	Remarks
Key Generation Algorithm	generates a private key and a corresponding public key
Signing Algorithm	given a message and a private key, produces a signature
Signature Verifying Algorithm	given the message, public key and signature, either accepts or rejects the message's claim to authenticity

Scheme	Description	Remarks
RSA	one of the first public-key cryptosystems based on the practical difficulty of the factorization of the product of two large prime numbers.	factoring problem
RSA-PSS	a cryptographic signature scheme designed by Mihir Bellare and Phillip Rogaway	PKCS#1 v2.1
DSA	a Federal Information Processing Standard for digital signatures, based on the mathematical concept of modular exponentiation and the discrete logarithm problem
ECDSA	a variant of the DSA which uses elliptic curve cryptography

ECDSA

$(CURVE,G,n)$
$CURVE:y^{2}=x^{3}+ax+b$
$n\times G=O$
$Q_{A}=d_{A}\times G\qquad (1\leqslant d_{A}\leqslant n)$

Step	Equation	Remarks
calculate message hash $e$	$e=HASH(m)$
calculate $z$	$z=leftmostbits(e,L_{n})$
select secure random $k$	$1\leqslant k\leqslant n$	cryptographically secure random
calculate the curve point $(x_{1},\,y_{1})$	$(x_{1},\,y_{1})=k\times G$	public key
calculate $r$	$r=x_{1}\,mod\,n$
calculate $s$	$s=k^{-1}(z+rd_{A})$

Symbol	Concept	Remarks
$G$	elliptic curve base point
$n$	integer order of $G$	prime number
$d_{A}$	private key	randomly selected
$Q_{A}$	public key	calculated by elliptic curve
$e$	message
$(r,s)$	signature

• Understanding How ECDSA Protects Your Data.
• Generate EC public key from byte array private key in native java (7+) (Feb 16 '18)

• ECDSA: The digital signature algorithm of a better internet (2014. 03. 11)
• A (Relatively Easy To Understand) Primer on Elliptic Curve Cryptography (2013. 10. 24)
• ECDSA

• RFC 5480 - Elliptic Curve Cryptography Subject Public Key Information
  • Specifies the format of the subjectPublicKeyInfo field in X.509 certificates

Digital Certificate

• Digital certificate (Public key certificate)
  • An electronic document used to prove the ownership of a public key
  • Certificate = Key + Subject(Owner) + Digital Signature

• Chain of trust
• Certificate signing request (CSR)

X.509 Certificate

• X.509
  • an ITU(International Telecommunication Union) standard defining the format of public key certificates

• RFC-5280 Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile

Certificate  ::=  SEQUENCE  {
        tbsCertificate       TBSCertificate,
        signatureAlgorithm   AlgorithmIdentifier,
        signatureValue       BIT STRING  }

   TBSCertificate  ::=  SEQUENCE  {
        version         [0]  EXPLICIT Version DEFAULT v1,
        serialNumber         CertificateSerialNumber,
        signature            AlgorithmIdentifier,
        issuer               Name,
        validity             Validity,
        subject              Name,
        subjectPublicKeyInfo SubjectPublicKeyInfo,
        issuerUniqueID  [1]  IMPLICIT UniqueIdentifier OPTIONAL,
                             -- If present, version MUST be v2 or v3

        subjectUniqueID [2]  IMPLICIT UniqueIdentifier OPTIONAL,
                             -- If present, version MUST be v2 or v3
        extensions      [3]  EXPLICIT Extensions OPTIONAL
                             -- If present, version MUST be v3
        }

   Version  ::=  INTEGER  {  v1(0), v2(1), v3(2)  }

   CertificateSerialNumber  ::=  INTEGER

   Validity ::= SEQUENCE {
        notBefore      Time,
        notAfter       Time }

   Time ::= CHOICE {
        utcTime        UTCTime,
        generalTime    GeneralizedTime }

   UniqueIdentifier  ::=  BIT STRING

   SubjectPublicKeyInfo  ::=  SEQUENCE  {
        algorithm            AlgorithmIdentifier,
        subjectPublicKey     BIT STRING  }

   Extensions  ::=  SEQUENCE SIZE (1..MAX) OF Extension

   Extension  ::=  SEQUENCE  {
        extnID      OBJECT IDENTIFIER,
        critical    BOOLEAN DEFAULT FALSE,
        extnValue   OCTET STRING
                    -- contains the DER encoding of an ASN.1 value
                    -- corresponding to the extension type identified
                    -- by extnID
        }

• Structure

Certificate
    Version
    Serial Number
    Signature Algorithm
    Issuer
    Validity 
        Not Before
        Not After
    Subject
    Subject Public Key Info
        Public Key Algorithm
        Public Key
    Issuer Unique Identifier
    Subject Unique Identifier

Signature Algorithm
Signature

• Sample

$ openssl x509 -in ~/Library/"Group Containers"/group.com.docker/pki/front-proxy-client.crt -inform PEM -text -noout
Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 1198170262028128809 (0x10a0c181509f9229)
    Signature Algorithm: sha256WithRSAEncryption
        Issuer: CN=kubernetes
        Validity
            Not Before: Jul 16 00:14:06 2020 GMT
            Not After : Jul 16 00:14:07 2021 GMT
        Subject: CN=front-proxy-client
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                Public-Key: (2048 bit)
                Modulus:
                    00:c5:a7:3e:ab:aa:cf:a0:77:64:c5:a1:f2:1f:9e:
                    d6:df:0e:53:55:ac:b5:6b:62:a5:46:28:70:92:d5:
                    b7:c5:3c:b2:4e:74:6b:15:bb:aa:26:f6:00:e3:bf:
                    be:da:de:62:61:04:4c:d1:10:d9:a4:23:34:c4:c1:
                    e5:95:ff:de:8e:24:35:7c:9d:f1:2b:bc:c5:3b:f6:
                    23:f8:88:b3:f4:23:d2:96:1e:d6:84:8c:01:7b:ab:
                    2f:a5:90:46:83:21:29:dd:82:b6:39:ac:a9:83:ce:
                    08:91:cd:8a:b5:80:7b:c1:1c:c0:6c:63:75:57:51:
                    19:24:ba:4a:7b:d1:1e:01:93:4f:67:f9:91:5c:34:
                    6e:40:7f:a4:56:a3:f2:63:06:76:0b:a0:72:8e:d0:
                    ef:ed:54:dc:ed:a6:31:00:09:3d:8b:6f:b9:0c:e2:
                    14:d5:9b:e5:3a:d0:a1:64:c9:28:87:04:c3:a3:d7:
                    b6:bf:0f:06:c1:ac:06:ca:6f:bf:97:5b:13:ea:37:
                    7e:09:e5:b8:00:75:2a:dc:cf:53:d4:6d:da:a3:93:
                    82:f8:3c:85:62:ee:4c:a4:e6:95:40:bc:b2:0b:26:
                    40:60:d4:2e:29:57:28:8c:22:62:ff:e2:46:7e:34:
                    34:80:9a:47:11:f2:91:e5:16:f4:9c:d2:db:c2:fc:
                    d9:87
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Key Usage: critical
                Digital Signature, Key Encipherment
            X509v3 Extended Key Usage: 
                TLS Web Client Authentication
    Signature Algorithm: sha256WithRSAEncryption
         91:76:cd:17:27:db:34:1c:5b:8b:cd:b8:d3:29:05:19:4d:aa:
         58:9c:eb:8a:fb:d3:3a:63:18:39:e5:5c:9e:5e:fc:f5:4c:fc:
         c8:5a:b0:ce:cd:87:cc:9c:98:7a:45:8c:35:9d:a8:4b:2f:32:
         19:95:01:37:7b:fb:9e:b4:7c:37:0c:6f:07:46:18:ba:44:b5:
         59:03:8d:4b:f1:b6:72:5c:79:a2:df:ad:59:c1:31:f2:29:84:
         26:95:b8:69:ac:b7:ee:19:fd:13:41:74:f0:9d:99:50:d6:4c:
         8a:05:93:b3:a9:19:db:c0:a0:b2:ca:17:15:1f:10:00:e1:bf:
         5b:f9:a0:76:e1:8d:df:da:60:72:87:1c:d0:c9:28:6f:65:41:
         4f:f6:9b:2a:7c:ab:64:fc:f4:1a:64:a6:43:3f:0b:30:a9:53:
         0e:a1:61:df:aa:ce:17:cc:7f:cf:07:c8:31:c7:a0:c7:b6:21:
         e0:d6:66:a0:0d:20:ee:d6:14:34:38:75:2f:6d:ae:3b:5d:fe:
         ea:16:d8:a9:01:59:9e:1c:31:04:72:03:26:98:1f:ef:f4:60:
         8c:ec:a9:c5:a3:41:13:0e:38:17:fa:7f:8d:36:fe:21:ca:41:
         e7:11:48:27:11:48:79:7d:af:ef:32:97:7b:2d:dd:b5:1d:cb:
         55:72:f7:df

• Certificate filename extensions

Extension	Description	Remarks
.pem	(Privacy-enhanced Electronic Mail) Base64 encoded DER certificate, enclosed between "-----BEGIN CERTIFICATE-----" and "-----END CERTIFICATE-----"
.cer, .crt, .der	usually in binary DER form, but Base64-encoded certificates are common too
.p12	PKCS#12, may contain certificate(s) (public) and private keys (password protected)
.pfx	PFX, predecessor of PKCS#12

PKI

• Public key infrastructure (Wikipedia)
  • a set of roles, policies, hardware, software and procedures needed to create, manage, distribute, use, store and revoke digital certificates and manage public-key encryption
• Public Key Infrastructure (MSDN)

• Certificate authority
  • an entity that issues digital certificates

• Distinguished Name
  • RFC 1779 : A String Representation of Distinguished Names
  • LDAP DNs and RDNs
  • Distinguished Names
    • uniquely identifies an entity in an X.509 certificate

• RFC 5280 : Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile

Concept	Description	Remarks
Authority Key Identifier	The authority key identifier extension provides a means of identifying the public key corresponding to the private key used to sign a certificate
Issuer	The issuer field identifies the entity that has signed and issued the certificate

• Basics of Digital Certificates and Certificate Authority
• Epic CA Fails

HSM

• Secure Cryptographic Operations with Hardware Security Modules (Aug 6, 2018)
  • Secured key management process
  • Increase the throughput of the system
  • Strong key generation
  • Can meet current standards and regulations on cyber security - FIPS 140-2
• Standard API for connecting HSMs with client applications (Aug 14, 2018)
  • Public Key Cryptography Standard #11(PKCS #11)
• You don’t need to buy a HSM to see how it works (Aug 23, 2018)
• Want to know how to talk to a HSM at code level? (Aug 27, 2018)
• Want to know how to talk to a HSM at code level? — Part 2 (Oct 1, 2018)

Key Store

• Android KeyStore System
• How Secure is your Android Keystore Authentication ? (21 August 2019)

OAuth

• OAuth 2.0 Specifications
• RFC 6749 - The OAuth 2.0 Authorization Framework

• An Introduction to OAuth 2 (July 21, 2014)
• OAuth 2 Simplified
• OAuth 2.0 Tutorial
• Requesting an OAuth 2.0 token
• Client Credentials Flow

HTTP Authentication

• RFC-7235 Hypertext Transfer Protocol (HTTP/1.1): Authentication
  • HTTP provides a general framework for access control and authentication, via an extensible set of challenge-response authentication schemes, which can be used by a server to challenge a client request and by a client to provide authentication information.
• HTTP authentication (MDN)
• HTTP Authentication Scheme Registry
  • Basic, Bearer, Digest, HOBA, Negotiate, OAuth, ...

• Basic access authentication (Wikipedia)
• Digest access authentication (Wikipedia)
• Bearer Authentication
• How to define the basic HTTP authentication using cURL correctly? (Sep 22 '14)

• HTTP Authentication Schemes

Name	Full Name	Description	Remarks
Basic	Basic HTTP Authentication	the client needs to authenticate itself with a user-id and a password for each protection space ("realm").
Digest	HTTP Digest Access Authentication	A valid response contains an unkeyed digest of the username, the password, the given nonce value, the HTTP method, and the requested URI.
OAuth	OAuth 1.0
Bearer	OAuth 2.0 Bearer Token	A security token with the property that any party in possession of the token (a "bearer") can use the token in any way that any other party in possession of it can.

• Related HTTP Headers

Header	Type	Description	Remarks
Authorization	Request	allows a user agent to authenticate itself with an origin server
Proxy-Authorization	Request	allows the client to identify itself (or its user) to a proxy that requires authentication.
WWW-Authenticate	Response	indicates the authentication scheme(s) and parameters applicable to the target resource.
Proxy-Authenticate	Response	indicates the authentication scheme(s) and parameters applicable to the proxy for this effective request URI

• Related Status Codes

Status Code	Description	Remarks
401 Unauthorized	indicates that the request has not been applied because it lacks valid authentication credentials for the target resource.
407 Proxy Authentication Required	indicates that the client needs to authenticate itself in order to use a proxy.

TLS

• RFC 5246: The Transport Layer Security (TLS) Protocol Version 1.2
• TLS (on Wikipedia)
• TLS handshake
• Creating a TLS encryption key and certificate
• TLS Security 4: SSL/TLS Certificates
• Transport Layer Security (TLS)

• What are root and intermediate SSL certificates?

• Server Name Indication (on Wikipedia)
• Wildcard Certificate
• DV OV and EV Certificates (July 1, 2015)
  • Domain Validated, Organization Validated, Extended Validation

• SSL/TLS Certificate Explained – How to Get TLS Certificate?

• Speeding up TLS: enabling session reuse (September 27, 2011)

• HTTP Public Key Pinning (on Wikipedia)
• HTTP Public Key Pinning Extension HPKP for Apache, NGINX and Lighttpd (14 April 2015)

SSH

• How To Set Up SSH Keys
• SSH Tutorial for Linux
  • Running Commands Over SSH
• Generating SSH Keys on GitHub Help

Elements

Element	Description	Remarks
passphrase	password for the private key
~/.ssh/authorized_keys	a list of public keys to allow to in-access into this account from outside	used when accepting others
~/.ssh/known_hosts	a list of public keys to allow for current user to out-access	used when accessing outer server
~/.ssh/id_dsa, ~/.ssh/id_rsa	a private key of current account
~/.ssh/id_dsa.pub, ~/.ssh/id_rsa.pub	a public key of current account

Commands

• Ubuntu Manpage: ssh
• ssh-keygen(1) - Linux man page
• Ubuntu Manpage: ssh-keygen
• Ubuntu Manpage: scp

Readings

ssh

• A few ways to execute commands remotely using SSH
  • To authenticate using SSH keys, a user must have an SSH key pair on their local computer. On the remote server, the public key must be copied to a file within the user's home directory at ~/.ssh/authorized_keys. This file contains a list of public keys, one-per-line, that are authorized to log into this account.
• How have both local and remote variable inside an SSH command(Dec 11 '12)
• Using while loop to ssh to multiple servers
  • Don't miss -n option of ssh when used inside while loop to avoid eating all stdin at the fist iteration.

scp

• scp files from multiple directories on local to multiple directories on remote in one command (Jul 18 '16)
• 12 scp command examples to transfer files on Linux (Mar 15, 2014)

Port Forwarding

• Port forwarding (on Wikipedia)
  • Local port forwarding
  • Remote port forwarding
  • Dynamic port forwarding

Local port forwarding

    Application --- Local Port ------- Bastion Host(Jump Server) ------- Destination Server
            Client side                                                     Remote side

Remote port forwarding
    
    @TODO

• A Guide to SSH Port Forwarding/Tunnelling (FEBRUARY 10, 2018)
• OpenSSH/Cookbook/Proxies and Jump Hosts
• How to Use SSH Tunneling to Access Restricted Servers and Browse Securely (JULY 12, 2017)
• Relay two SSH connections together (Nov 29 '17)
• Using ProxyJump with SSH and SCP (Nov 2, 2017)
• SSH tunneling error: “channel 1: open failed: administratively prohibited: open failed” (Jun 1 '11)
• Advanced SSH Tunneling (October 6, 2015)

DID

• Decentralized Identifiers (DIDs) v0.9 Specification
• GitHub / W3C Credentials Communtiy Group
• Verifiable Claims Use Cases

JWT

• https://jwt.io/
• Desc. : an open, industry standard RFC 7519 method for representing claims securely between two parties.

---

UI, UX

• List of common generic widgets
  • button, check box, radio, list box, drop-down list, combo box, spinner, slider, text box, tree, grid, menu, menu bar, toolbar, label, tooltip, balloon help, status bar, progress bar, inforbar
• Media controls
• Basic Timeline Elements
• Off-Canvas Top

Widget Toolkit

a library or a collection of libraries containing a set of graphical control elements (called widgets) used to construct the graphical user interface (GUI) of programs.

• List of widget toolkits

Toolkit	Description	License	Remarks
Qt	a widget toolkit for creating graphical user interfaces as well as cross-platform applications that run on various software and hardware platforms such as Linux, Windows, macOS, Android or embedded systems.	GPL 2.0, GPL 3.0, LGPL 3.0
GTK	a free and open-source cross-platform widget toolkit for creating graphical user interfaces (GUIs).	LGPL
Tk	a free and open-source, cross-platform widget toolkit that provides a library of basic elements of GUI widgets for building a graphical user interface (GUI) in many programming languages.	BSD-style
wxWidgets	a widget toolkit and tools library for creating graphical user interfaces (GUIs) for cross-platform applications.

Real-time Graph

• D3.js/Path Transitions (January 19, 2012)
• Create Real-Time Graphs with PubNub and D3.js
• D3 Real-Time streamgraph (Graph Data Visualization)

---

Architecture and Model

• Building blocks of Domain-driven design
• Multilayered architecture/Common layers
• Fluent interface

• Manifesto for Agile Software Development(2001)
• Manifesto for Software Craftsmanship(2009)
• The Reactive Manifesto

• The Death of the Architect (Dec. 24, 17)

Architecture

• REST(REpresentational State Transfer) (Wikipedia)
• HATEOAS(Hypermedia As The Engine Of Application State) (Wikipedia)
• Microservices (Wikipedia)

• Architectural Styles and the Design of Network-based Software Architectures

• Twelve-factor App
  1. One codebase tracked in revision control, many deploys
  2. Explicitly declare and isolate dependencies
  3. Store config in the environment
  4. Treat backing services as attached resources
  5. Strictly separate build and run stages
  6. Execute the app as one or more stateless processes
  7. Export services via port binding
  8. Scale out via the process model
  9. Maximize robustness with fast startup and graceful shutdown
  10. Keep development, staging, and production as similar as possible
  11. Treat logs as event streams
  12. Run admin/management tasks as one-off processes

• Microservice Trade-Offs (Martin Fowler, 01 July 2015)

Event-Driven Architecture

• Event-driven architecture
• Event-driven architecture with Pub/Sub

Pattern

• Software design pattern
• Design Patterns
• GRASP (General Responsibility Assignment Software Patterns)
• SOLID (Single responsibility, Open-closed, Liskov substitution, Interface segregation and Dependency inversion)
• P of EAA(Patterns of Enterprise Application Architecture)
• DRY (Don't Repeat Yourself)
• Dont Repeat Yourself
• Divide and Conquer

• Design Patterns: Elements of Reusable Object-Oriented Software (by Erich Gamma, Richard Helm, Ralph Johnson, John Vlissides)
• Applying UML and Patterns: An Introduction to Object-Oriented Analysis and Design and Iterative Development (by Craig Larman)

• Builder pattern(Wikipedia)
• The freeze thaw pattern

• The Singleton Pattern, 20 Years Later (Apr. 06, 16)

UML

• UML Specification (OMG)

Version	Normative Spec	Informative Spec	Remarks
2.5.1	OMG UML Version 2.5.1 (2017-12-05, formal)	OMG UML Version 2.5.1 (2017-12-06, formal, with change bar)

• UML Resources

• UML Tutorials by Sparx Systems
• UML 2.5 Diagrams Overview
• Allen Holub's UML Quick Reference

• UML basics: An introduction to the Unified Modeling Language
• UML basics: The class diagram
• UML basics: The sequence diagram
• UML basics: The component diagram
• Business Modelling: UML vs. IDEF
• UML Association Reference

• UML Association vs Aggregation vs Composition

Profile, Constraint

• UML Profile
• UML Constraint
• Tagged Value
• UML Stereotypes

Standard Stereotypes

• Overview of the UML Standard profile
• Standard stereotypes for UML models (15.11.2016)

Applieds to	Stereotype	Description	Remarks
Class	Type	Specifies the behavior of an object without stating how it is implemented.	Interface ?
	Metaclass	Instances of this class are also classes.
	Utility	A collection of static functions. The class has no instances
Dependency	Call	The client class calls the operations of the supplier.
	Create	The client class creates instances of the supplier.
	Instantiate	The client creates instances of the supplier.
	Derive	The client element is computed completely or partly from the supplier.
	Refine	The client class, component, or package provides more information about the specification or design than the supplier.
	Trace	The client element is part of the design that realizes the supplier.
Operation	Create	This operation is a constructor.
	Destroy	The operation destroys its instance.

OCL

• OCL (Object Constraint Language) simple tutorial
• OCL Operations Reference

Type	Operation	Description	Example	Remarks
Collection	any(expr)	Returns any element contained in self that validates the condition expr, null otherwise.	Sequence{1.2, 2.3, 5.2, 0.9}->any(self < 1)	filter operation
	collect(expr)	Returns a collection containing the result of applying expr on all elements contained in self.	Sequence{'first', 'second'}->collect(toUpper())	map operation

Class Diagram

• UML Class Diagram Tutorial
• UML 2 Tutorial - Class Diagram
• Qualifier
• Nested Classifier

Activity Diagram

• What is Activity Diagram?
• Activity Diagram
• Activity diagrams: What they are and how to use them (April 22, 2004)
• UML 2 Activity Modeling for Domain Experts

Sequence Diagram

• A Quick Introduction to UML Sequence Diagrams
• Sequence Diagram
• Describe control flow with fragments on UML sequence diagrams (2016. 11. 15)

• Combined Fragment
• Combined Fragment

• UML Message : Messages by Action Type, Messages by Presence of Events
• Specifying the type of a message in a UML sequence diagram

• Message Sort

Type	Description	Line	Arrow Head	Remarks
synchCall	The message was generated by a synchronous call to an operation.	Solid	Filled
asynchCall	The message was generated by an asynchronous call to an operation	Solid	Open
asynchSignal	The message was generated by an asynchronous send action.	Solid	Open
createMessage	The message designating the creation of another lifeline object.
deleteMessage	The message designating the termination of another lifeline.
reply	The message is a reply message to an operation call.	Dashed	Open

• Message Kind

Kind	Description	Notation	Remarks
complete	sendEvent and receiveEvent are present
lost	sendEvent present and receiveEvent absent
found	sendEvent absent and receiveEvent present
unknown	sendEvent and receiveEvent absent	should not appear

• Fragments

Fragment	Title	Description	Remarks
alt	Alternatives	represents a choice of behavior
opt	Option	represents a choice of behavior where either the (sole) operand happens or nothing happens
loop	Loop	represents a loop
break	Break	represents a breaking scenario
par	Parallel	represents a parallel merge between the behaviors of the operands
seq	Weak Sequencing	represents a weak sequencing between the behaviors of the operands
strict	Strict Sequencing	represents a strict sequencing between the behaviors of the operands
neg	Negative	represents traces that are defined to be invalid
critical	Critical Region	represents a critical region - the region is treated atomically
ignore	Ignore	designates that there are some message types that are not shown
assert	Assertion	represents an assertion

Data Modeling

• Database normalization (Wikipedia)
• Database Normalization Basics
• Database Normalization (Mar 22, 2000)

• Database Design – 2nd Edition (Adrienne Watt)
• ERwin Data Modeling Method Guide

• A Universal Person and Organization Data Model (July 1, 2002)
• Party domain model
• Party Data Model
• Data Model for Parties, Roles and Customers (January 24th. 2014)
• Choosing a Primary Key: Natural or Surrogate?

Common Data-types

• e-GIF(e-Government Interoperability Framework) Government Data Standards Catalogue (UK)

Datatype	Facet	Standard/Guideline	Remarks
Address		BS7666 1994
Date	Max 10 Characters in the format CCYY-MM-DD
e-Mail Address	len < 255	IETF RFC2822

• Workforce Data Standards (UK, Jan 2010)

Datatype	Facet	Standard/Guideline	Remarks
Person Family Name	Alphanumeric, len <= 100
Person Given Name	Alphanumeric, len <= 100

• Name Standards
• Personal names around the world

• ISO 3166-1 alpha-3 : 3-letter Country Codes
• List of long place names
• Postal code

Common Glossary

• “state” or “status”? When should a variable name contain the word “state”, and when should a variable name instead contain the word “status”? (Nov 24 '13)

Glossary	Description	Remarks
state	describe a stage in a process
status	describe an outcome of an operation	HTTP Status Codes, Amazon Order Status, JIRA Ticket Status

Common Abbreviation

• The abbreviations used in the 1913 edition of Webster's dictionary
• Abbreviations | Oxford English Dictionary
• USPS / Postal Addressing Standards / Business Word Abbreviations
• USPS / Postal Addressing Standards / Street Suffix Abbreviations

Full	Abbreviation	Description	Remarks
account	acct.
approval	apprv.
authentication	auth.
authorization	authz.
bridge	bdg
business	biz
campaign	cmpgn
collection	collectn			construction	constr
contract	contr.
corporation	corp.
customer	cust
description	descr		desc is reserved word of Oracle and MySQL
document(s)	doc.
payment	pymt.
private	pvt		prv
public	pub
receipt	recpt
reference	ref
representative	rep
request	req.
response	resp.
special	spcl.
transfer	transf
value	val.

Data Analysis

• Thomas Kejser's Database Blog

• Data Warehousing Overview
• Data Warehouse Architectures
  • Staging Area, Enterprise Warehouse, Data Marts
• Data Warehouse reference architecture(September 26, 2011)
• Data warehouse architectures and development strategy(PDF)

• Time Series Tutorial

CRISP-DM

• CRISP-DM (Cross-industry standard process for data mining)
  • an open standard process model that describes common approaches used by data mining experts.
• Introduction to CRISP-DM

Process Modeling

BPMN

• Business Process Model and Notation (on Wikipedia)

• BPMN Homepage
• BPMN Quick Guide
• BPMN 1.2 tutorial

• BPMN Examples
• BPMN Online Examples

CORBA

• The CORBA Component Model (September 01, 2004)

REST

• Representational state transfer (Wikipedia)
• Representational State Transfer (REST)
• HATEOAS(Hypermedia As The Engine Of Application State) (Wikipedia)
• List of HTTP header fields (Wikipedia)
• List of HTTP status codes (Wikipedia)
• HTTP ETag (Wikipedia)

• OpenAPI Specification Ver. 2.0
• OpenAPI Specification Ver. 3.1.0
• OData (Open Data Protocol)
  • an OASIS standard that defines a set of best practices for building and consuming RESTful APIs.
  • OData Documentations
• RAML (RESTful API Modeling Language)

• RESTful Web Services Cookbook (Subbu Allamaraju, O'Reilly, March 2010)
• Google Cloud APIs API Design Guide
• Microsoft REST API Guidelines
• Thoughts on RESTful API Design

• Best Practices for Designing a Pragmatic RESTful API (4 Jun 2013)
• REST API Syntax (24 Oct 2014)
• GitHub API Overview
  • Schema, Parameters, Client Errors, Authentication, Rate Limiting, User Agent Required, Conditional requests, Cross Origin Resource Sharing, Timezones
• Twitter API > Things Every Developer Should Know
• Twitter API > Security
• Twitter API > Error Codes Responses
• New v2 API: What’s Not There Is Just As Important As What Is
• Imgur API Version 3 > Error Handling
• API Design Guidance: File Upload (22 FEB, 2021)
  • Direct file upload(image/jpeg), Multipart HTTP request(multipart/form-data), Two-step metadata + upload

• Understanding REST Parameters
  • Resource Parameters, QUERY Parameters, HEADER parameters, TEMPLATE Parameters, MATRIX Parameters
• REST API Best practices: Where to put parameters? (Oct 26 '10)
• Understanding REST Headers and Parameters
• When and How to Use Custom HTTP Headers
• Accept-Language used for locale setting
• The 5 laws of API dates and times (March 20, 2013)
• GitHub API > Timezones
• GitHub API > Traversing with Pagination
• API Rate Limits of Twitter API
• Examples of HTTP API Rate Limiting HTTP Response headers (Apr 15 '13)
• Google Drive APIs > REST > Batching Requests
• Google Drive APIs > REST > Upload Files
• Batch Processing (OData Version 3.0)

• URL manipulation (URL rewriting)

• REST vs. gRPC: Battle of the APIs (8 May 2018)
• API Battles – gRPC vs. REST (APRIL 11, 2019)
• API Is Dead – Long Live the APIs

Examples

• Twitter REST APIs
• GitHub API v3
• GitLab REST API
• Gmail API Reference
• Google Drive REST API
• StatusPage.io
• Stripe API

Service	Category	API	Description	Remarks
Tweet	Tweets	GET /2/tweets/:id
		GET /2/tweets/:id/retweeted_by
		GET /2/tweets/:id/liking_users
		GET /2/users/:id/liked_tweets
	Spaces	GET /2/spaces/by/creator_ids
GitHub	Activity	GET /networks/{owner}/{repo}/events	List public events for a network of repositories
GitLab	Project	GET projects/:id/access_tokens	List project access tokens
		POST /projects/:id/jobs/:job_id/cancel	Cancel a job
		POST /projects/:id/jobs/:job_id/retry	Retry a job
		POST /projects/:id/jobs/:job_id/erase	Erase a job
		POST /projects/:id/jobs/:job_id/play	Play a job

Common Patterns

Pattern	Description	Remarks
POST resources	Add a new resource.
PUT resources/{id}/state	Update a resource into the state.
POST resources/{id}/action	Apply action to a resource.	action : remove, disable, sell, buy, transfer, ...
GET resources/count	Get the number of resources.
GET resources/mine/count	Get the number of resources owned by the current authenticated user.
GET resources/state/count	Get the number of resources in a state.
GET resources/state	List resources in a state within an interval.
GET resources/valid
GET resources/invalid
GET resources/mine	List resources owned by the current authenticated user.
GET resources/recent?limit={n}	List recent resources up to a specified number.
GET resources/last

• PUT resources/{id}/state and POST resources/{id}/state are somewhat exchangeable.

Examples

POST bids

PUT bids/{id}/canceled
PUT bids/{id}/accepted
PUT bids/{id}/rejected

GET bids/count
GET bids/accepted?pageSize={m}&page={n}
GET bids/accepted/count?from={startDate}&to={endDate}
GET bids/accepted?from={startDate}&to={endDate}&pageSize={m}&page={n}
GET bids/recent?limit=10

Base/Common API

URL	Title	Remarks	GET /releasenotes	List release notes
GET /locales	List all available locales
GET /timezones	List all available timezones

OpenAPI

• OpenAPI Initiative (OAI)
• OpenAPI Guide

Version	Specification	Remarks
2.0	OpenAPI Specification Ver. 2.0
3.1.0	OpenAPI Specification Ver. 3.1.0

OpenAPI 3.x

• Runtime Expressions
  • Runtime expressions allow defining values based on information that will only be available within the HTTP message in an actual API call. This mechanism is used by Link Objects and Callback Objects.

Datatypes

• Primitive Datatypes
• Number type/format
• String type/format

Type	Format	Remarks
integer
integer	int32	signed 32 bits
integer	int64	signed 64 bits (a.k.a long)
number
number	float
number	double
boolean
string
string	byte	base64 encoded characters
string	binary	any sequence of octets
string	date	'yyyy-MM-dd' format (full-date in RFC3339 or ISO8601)
string	date-time	'yyyy-MM-ddTHH:mm:ss(+|-)hh:nn' format (date-time in RRC3339 or ISO8601)
string	password	A hint to UIs to obscure input

Type	Format	Remarks
string	uri	RFC-3986
string	hostname	RFC-1123
string	email	RFC-5321
string	uuid	RFC-4122
string	regex	JSON Schema/Regular Expression

File Upload/Download

• File Upload

POST /upload
Host: example.com
Content-Length: 808
Content-Type: image/png

[file content goes there]

• Multipart Requests

POST /upload HTTP/1.1
Content-Length: 428
Content-Type: multipart/form-data; boundary=abcde12345
--abcde12345
Content-Disposition: form-data; name="id"
Content-Type: text/plain
123e4567-e89b-12d3-a456-426655440000
--abcde12345
Content-Disposition: form-data; name="address"
Content-Type: application/json
{
  "street": "3, Garden St",
  "city": "Hillsbery, UT"
}
--abcde12345
Content-Disposition: form-data; name="profileImage "; filename="image1.png"
Content-Type: application/octet-stream
{…file content…}
--abcde12345--

• Response That Returns a File

OpenAPI 2.0

• OpenAPI 2.0 Parameter Object

Microservices

• MonolithFirst (Martin Fowler, 3 June 2015)
  • Almost all the successful microservice stories have started with a monolith that got too big and was broken up
  • Almost all the cases where I've heard of a system that was built as a microservice system from scratch, it has ended up in serious trouble.
• MicroservicePremium (Martin Fowler, 13 May 2015)

• The Death of Microservice Madness in 2018 (2018)
• Why microservices may not be for everybody (February 4, 2017)
• The Microservices Hype (Aug 25, 2017)
  • Microservices give a lot of benefits, but with those benefits comes a lot of complexity, and this kind of complexity would drive you off the road of focusing on the business, which at the end is what really matters. Distribution, communication, discovery, isolation, health, are some of the topics that come hand in hand with this approach, and every each of them is its own monster to control.

Misc

CRISP-DM

• What is CRISP DM?
  • a process model with six phases that naturally describes the data science life cycle.
• Cross-industry standard process for data mining

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Software Engineering

• Rational Unified Process
  • RUP (Wikipedia)
  • Four project life-cycle phases
    • Inception phase
    • Elaboration phase
    • Construction phase
    • Transition phase
  • Six engineering disciplines
    • Business modelling
    • Requirements
    • Analysis and design
    • Implementation
    • Test
    • Deployment
  • Three supporting disciplines
    • Configuration and change management
    • Project management
    • Environment

Quality Assurance

• ISO 9126

    Functionality ------+---- Suitability
                        +---- Accuracy
                        +---- Interoperability
                        +---- Security
                        +---- Functionality Compliance

    Reliability --------+---- Maturity
                        +---- Fault Tolerance 
                        +---- Recoverability
                        +---- Reliability Compliance

    Usability ----------+---- Understandability
                        +---- Learnability
                        +---- Operability
                        +---- Attractiveness
                        +---- Usability Compliance

    Efficiency ----------+---- Time Behaviour
                        +---- Resource Utilization
                        +---- Efficiency Compliance

    Maintainability ----+---- Analysability
                        +---- Changeability
                        +---- Stability
                        +---- Testability
                        +---- Maintainability Compliance

    Portability --------+---- Adaptability
                        +---- Installability
                        +---- Co-existence
                        +---- Replaceability
                        +---- Portability Compliance

• ISO/IEC 25010

    Functional Suitability ----+---- Functional Completeness
                               +---- Functional Correctness
                               +---- Functional Appropriateness

    Performance Efficiency ----+---- Time Behaviour
                               +---- Resource Utilization
                               +---- Capacity
    
    Compatibility -------------+---- Co-existence
                               +---- Interoperability

    Usability -----------------+---- Appropriateness Recognizability
                               +---- Learnability
                               +---- Operability
                               +---- User Error Protection
                               +---- User Interface Aesthetics
                               +---- Accessibility
    
    Reliability ---------------+---- Maturity
                               +---- Availability
                               +---- Fault Tolerance 
                               +---- Recoverability

    Security ------------------+---- Confidentiality
                               +---- Integrity
                               +---- Non-repudiation
                               +---- Accountability
                               +---- Authenticity

    Maintainability -----------+---- Modularity
                               +---- Reusability
                               +---- Analysability
                               +---- Modifiability
                               +---- Testability

    Portability ---------------+---- Adaptability
                               +---- Installability
                               +---- Replaceability

Testing

• Unit Testing Guidelines
  • Keep testing at unit level
  • Keep tests independent
  • Focus on execution coverage first
  • Cover boundary cases
  • Provide a random generator : a simple way to improve test coverage further is to generate random parameters so that the tests can be executed with different input every time.
  • Test each feature once

• 8 Principles of Better Unit Testing (09/24/2012)

• Testings by Level

Testing	Description	Remarks
Unit Testing	Tests that verify the functionality of a specific section of code, usually at the function level
Integration Testing	Evaluate the compliance of a system or component with specified functional requirements
System Testing	Evaluate the system's compliance with its specified requirements on a complete integrated system
Acceptance Testing	A test conducted to determine if the requirements of a specification or contract are met

Performance Testing

• Software performance testing

Type	Description	Remarks
Load Testing	Usually conducted to understand the behaviour of the system under a specific expected load.
Stress Testing	Normally used to understand the upper limits of capacity within the system.

• Sun Java System Application Server 9.1 / Establishing Performance Goals

Initially, as the number of users increases, throughput increases correspondingly. However, as the number of concurrent requests increases, server performance begins to saturate, and throughput begins to decline.
A user submits a request, the server receives and processes the request, and then returns a result, at which point the user spends some time before submitting a new request. The time between one request and the next is called think time.

Version Control

• Version Control
• Semantic Versioning

• APR's Version Numbering

  • Versions are denoted using a standard triplet of integers: MAJOR.MINOR.PATCH. The basic intent is that MAJOR versions are incompatible, large-scale upgrades of the API. MINOR versions retain source and binary compatibility with older minor versions, and changes in the PATCH level are perfectly compatible, forwards and backwards.

• Public/Project Versioning - Best Practices
• Working with conflicting changes
  • 'Override and Update' and 'Mark as Merged' in Eclipse's Team CVS plug-in are clearly explained with simple case.
• M2E updatesite and gittags
  • Best practice on version control policies
• Making Subversion Releases
• Looking for free Github (enterprise/FI edition) alternative for private installation

Case	Scheme	Remarks
Maven Project Versions	<major version>.<minor version>.<incremental version>-<qualifier>
Eclipse Version Numbering	major.minor.service.qualifier
.NET Framework Assembly Versioning	<major version>.<minor version>.<build number>.<revision>

Issue Tracking

• Life Cycle of a Bug in Bugzilla 4.0
• The Trac Ticket Workflow System
• Working with workflows in JIRA 7.0

Contents Management

• 2011 Open Source CMS Market Share Report

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misc

Books

• Amazon Best Sellers / Computers & Technology
  • Amazon Best Sellers / Computer Science
  • Amazon Best Sellers / AI & Machine Learning
  • Amazon Best Sellers / Databases & Big Data

• WikiDocs (Korean)

Documentation

• Typographic Conventions of OpenShift Online User Guide

HP Notebook

• Using System Recovery, Factory Reset and Minimized Image Recovery Options
• Performing an HP System Recovery (Windows 7)
• HP Unified Extensible Firmware Interface (UEFI) Support Environment
  • To get files in HP_TOOLS partition.

Software Licenses

• License List
• Comparison of free and open-source software licenses

• Open Source Guides

Examples

• Microsoft
  • Credits, Copyright and Third Party Notices of Windows 10

• Adobe
  • Product Licenses and Terms of Use
  • Third Party Software Notices and/or Additional Terms and Conditions

Hardware

• Open Compute Project
  • to develop servers and data centers following the model traditionally associated with open source software projects.

• UEFI(Unified Extensible Firmware Interface)
  • a specification that defines a software interface between an operating system and platform firmware

• Data Transfer Rates Compared (RAM vs PCIe vs SATA vs USB vs More!) (7th Aug 2018)

Computer Bus

• Computer Bus
  • a communication system that transfers data between components inside a computer, or between computers.
• Examples of internal computer buses
  • PATA, SATA, PCIe
• Examples of external computer buses
  • RS-232, USB, Thunderbolt

Bus	Full Name	Description	Remarks
PATA	Parallel ATA, Parallel AT Attachment, Parallel Advanced Technology Attachment	an interface standard for the connection of storage devices such as hard disk drives, floppy disk drives, and optical disc drives in computers.	ATA, IDE
SATA	Serial ATA, Serial AT Attachment	a computer bus interface that connects host bus adapters to mass storage devices such as hard disk drives, optical drives, and solid-state drives
PCIe	PCI Express,Peripheral Component Interconnect Express	a high-speed serial computer expansion bus standard, designed to replace the older PCI, PCI-X and AGP bus standards.
M.2		a specification for internally mounted computer expansion cards and associated connectors
NVMe	Non-Volatile Memory(NVM) Express	an open logical device interface specification for accessing non-volatile storage media attached via a PCI Express (PCIe) bus.
USB	Universal Serial Bus	an industry standard that establishes specifications for cables and connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers.	USB 1.0, USB 2.0, USB 3.0, USB 3.1, USB4
Thunderbolt		the brand name of a hardware interface developed by Intel (in collaboration with Apple) that allows the connection of external peripherals to a computer.	Thunderbolt 1, Thunderbolt 2, Thunderbolt 3

Bus	Speed	Released in	Remarks
SATA 3.0	6 Gbit/s, 600 MB/s	2009
PCIe 3.0	1.0 GB/s ~ 15.8 GB/s	2010
PCIe 4.0	2.0 GB/s ~ 31.5 GB/s	2017
USB 2.0	1.5 Mbit/s (Low), 12 Mbit/s (Full), 480 Mbit/s (Hight)	2001
USB 3.0	5 Gbit/s, 500 MB/s	2011
USB 3.1	10 Gbit/s, 1.2 GB/s	2014
USB 3.2	20 Gbit/s, 2.4 GB/s	2017
Thunderbolt 2	20 Gbit/s	2013
Thunderbolt 3	40 Gbit/s	2015	USB 3.1, DP 1.2, PCIe 3

• What you need to know about Thunderbolt (FEB 24, 2011)
  • Thunderbolt supports data, video, audio, and power, you can use a single Thunderbolt port—and thus a single cable—to connect many of your peripherals.
  • Because Thunderbolt is based on PCI Express, it offers a direct connection to the PCI Express bus.
• Thunderbolt 3 Vs. USB-C: What's The Difference ? (July 24, 2017)
• USB 3.1 vs. Thunderbolt 3: The battle for the USB-C crown (Mar 7, 2017)
  • There are two different standards for the USB-C connector: USB 3.1 and Thunderbolt 3.

USB

• USB
• USB connector type quick reference
  • Type A, Type B, Type C, Mini-A, Mini-B, Mini-AB, Micro-A, Micro-B, Micro-AB
• USB Hardware

Type	USB 1.0	USB 1.1	USB 2.0	USB 2.0 Revised	USB 3.0	USB 3.1	USB 3.2	USB 4.0
Max. Transfer Rate	12 Mbps	12 Mbps	480 Mbps	480 Mbps	5 Gbps	10 Gbps	20 Gbps	40 Gbps
Type A	O	O	O	O	O	O
Type B	O	O	O	O	O	O
Type C				O	O	O	O	O

USB Power Delivery

Spec	Voltabe	Current	Power	Remark
Battery Charging (BC) 1.1	1.5 A	5 V	7.5 W
Battery Charging (BC) 1.2	1.5 A	5 V	7.5 W
USB-C	1.5 A	5 V	7.5 W
	3 A	5 V	15 W
Power Delivery 1.0/2.0/3.0 Type-C	5 A	20 V	100 W
Power Delivery 3.1 Type-C	5 A	48 V	240 W

• USB Power Delivery explained (April 25, 2022)
  • USB Power Delivery is much more powerful, supporting up to 240W of power to charge up even the most demanding gadgets such as laptops.
  • This handshaking approach supports voltage steps at 5V, 9V, 15V, 20V, and beyond for power outputs ranging from 0.5W to 240W.

• USB Power
• USB Battery Charging(USB BC)
• USB Power Delivery(USB PD)

• USB PD PPS(Programmable Power Supply)
  • Allows granular control over VBUS power, allowing a range of 3.3 to 21 V in 20 mV steps to facilitate constant-current or constant-voltage charging.

• "Certified USB Fast Charger" logo
  • For chargers that use "Programmable Power Supply" (PPS) protocol from the USB Power Delivery 3.0 specification

USB PD 1.0

• six fixed power profiles for different device categories

Voltage	Current	Power	Remarks
5 V	2 A	10 W
12 V	1.5 A	18 W
12 V	3 A	36 W
12 V	5 A	60 W
20 V	3 A	60 W
20 V	5 A	100 W

USB PD 2.x/3.x

• Drop fixed profiles in favor of more flexible power rules.
• Keep fixed voltage brackets but allow for a wider range of negotiated current levels

• Power Rules

Category	Power Range	Voltage	Current	Usage
Standard Power Range (SPR)	0.5 ~ 15 W	5 V	0.1 ~ 3.0 A	headphones, small USB accessories
	15 ~ 27 W	9 V	1.67 ~ 3.0 A	smartphones, cameras, drones
	27 ~ 45 W	15 V	1.8 ~ 3.0 A	tablets, small laptops
	45 ~ 100 W	20 V	2.25 ~ 3.0 A, 3.0 ~ 5.0 A	large laptops, displays
Extended Power Range (EPR)	100 ~ 140 W	28 V	3.75 ~ 5.0 A
	140 ~ 180 W	36 V	3.89 ~ 5.0 A
	180 ~ 240 W	48 V	3.75 ~ 5.0 A

SD Card

• SD card : a proprietary non-volatile memory card format developed by the SD Association (SDA) for use in portable devices.
• SD Association

• SD Memory Card Formatter (SD Association)

Business Solutions

• Business Processes

Process	Description	Remarks
Order Fulfillment	The complete process from point of sales inquiry to delivery of a product to the customer.

SAP R/3

• SAP Module Overview
• SAP Modules

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