Stream in Nodejs

reference: https://nodesource.com/blog/understanding-streams-in-nodejs/

Advantage：

• In a http example, do not need to put all file size into memories anymore
• prevent the low response speed or even crash caused by memory's over-limited
• process one chunk data each time

Principle：

Event Emitter of Node.js

Category：

• readable：可读
• writable：可写
• duplex：双工。可读也可写，互不干扰。
• transform：转换。从可写转成可读，链式调用，做数据处理

Implement：

1. native api:

• stream
• fs.createReadStream
• http
• socket
• process.stdin(out)
• zlib.createGzip: one of the most common transform stream

2. inherit
   to diy your own specific stream:

• inherit class (like Readable)
• redefine _read function

API：

• pipe/unpipe
• pipeline: multiple process in one line
• resume/pause
• push
• event:
  readable, data,
  error, finish, close, drain

Concept :

• mode: flowing & pause and several related events
• back pressure：背压，eg: 写不进去，wait the drain(下水道) event to continue

Streams Cheat Sheet:

fundamental
practice
flowing
readable & transform
writable & compound