post-stream

Efficiently and conveniently send number, string, boolean, null, undefined, object, buffer or stream to a stream.

npm install --save post-stream

---

API

Constructor

//Create a stream controler
new PostStream(config);

config:

• readable readable stream
• writable writable stream
• duplex duplex stream (such as tcp socket)
• maxSize data fragment max byte size, default 16MB. If when sending data greater than maxSize will throw a error. If when receiving data greater than maxSize ,this data will be discard.

StaticClassProperty

serialize(data: Array): Buffer

Serilize data. Pass a array, item type can be number, string, boolean, null, undefined, object or buffer.

parse(data: Buffer): Array

Parse data. Pass a has been serialized buffer.

ClassProperty

data: EventEmiter

This is a EventEmiter. Received data`s title is event name.

const ps = new PostStream({readable, writable});
ps.data.once('test', function(data){ data === 123 });
await ps.send('test', 123);

parseData: boolean

Parse received data. Default is true. If you set false, then you need use PostStream.parse to parse every received data.

const ps = new PostStream({readable, writable});
ps.parseData = false;
ps.data.once('test', function(data){
    const parsed = PostStream.parse(data); //return array
});
await ps.send('test', 123);

ClassMethod

send(title: string, ...data: any[]): Promise<void>

Send number, string, boolean, null, undefined, object or buffer to stream. The first argument must be a string, it is used for description the data. After that you can pass zero or more data as arguments. If a argument is object or array，it will be serialized( use JSON.stringify ). If you want send a buffer, don`t put it in object or array. This function will return a promise object.

const ps = new PostStream({readable, writable});
await ps.send('test');
await ps.send('test1', 123);
await ps.send('test2', 'string', 1, 3.5, true, null, undefined, { name: 'test' }, [1,2,3], Buffer.from('ttt'));

send(title: string, data: stream.Readable | stream.Duplex): Promise<void>;

Send a stream`s data to stream. You can only pass one stream as second argument. Other arguments will be ignore. Receiver side will receive a buffer, data comes from the send stream. This function will return a promise object.

const ps = new PostStream({readable, writable});
await ps.send('stream', fs.createReadStream('./testFile.txt'));
await ps.send('stream', fs.createReadStream('./testFile2.txt'));

sendSerializedData(title: string, data: Buffer): Promise<void>;

Directly send using PostStream.serialize serialized data.

const ps = new PostStream({readable, writable});
await ps.sendSerializedData('original', PostStream.serialize(['hello']));

close

close(): Promise<void>

Close readable stream and writable stream.

const ps = new PostStream({readable, writable});
await ps.close();

Event

'data'

Receive all data. This will be triggered when PostStream has received data. The first parameter is title, after that will be zero or more data, determined by when sending.

const ps = new PostStream(readableStream, writableStream);
ps.on('data', function (title, data1, data2[, ...data3]) { });

'end'

This will be triggered when the be controled stream trigger end event.

'close'

This will be triggered when the be controled stream trigger close event.

'error'

This will be triggered when the be controled stream trigger error event or when parsing data error.

Attention

If you want to use pipe to communicate with child process, you would better use two pipe instead of one. Because of don`t know why child send data to parent will lost one data fragment.(this is not this package`s problem)

//parent
 
const child_process = require('child_process');
const path = require('path');
const PostStream = require('post-stream');
 
const child = child_process.spawn(process.execPath, [path.resolve('./child.js')], {
    stdio: ['pipe', 'pipe', 'pipe', 'pipe', 'pipe']
});
const ps = new PostStream({readable:child.stdio[3], writable:child.stdio[4]});
ps.data.on('main', data => {
    console.log('main:', data)
});
ps.send('child',123);

//child
const fs = require('fs');
const PostStream = require('post-stream');
 
let readable = fs.createReadStream(null,{fd:4});
let writable = fs.createWriteStream(null,{fd:3});
const ps = new PostStream({readable, writable});
ps.data.on('child', data => {
    ps.send('main', data);
});