tcp-base

A base class for tcp client with basic functions

[![NPM version][npm-image]][npm-url]
[![Test coverage][codecov-image]][codecov-url]
[![npm download][download-image]][download-url]

[npm-image]: https://img.shields.io/npm/v/tcp-base.svg?style=flat-square
[npm-url]: https://npmjs.org/package/tcp-base
[codecov-image]: https://codecov.io/gh/node-modules/tcp-base/branch/master/graph/badge.svg
[codecov-url]: https://codecov.io/gh/node-modules/tcp-base
[download-image]: https://img.shields.io/npm/dm/tcp-base.svg?style=flat-square
[download-url]: https://npmjs.org/package/tcp-base

Install

``bash
npm install tcp-base --save
`

Node.js >= 6.0.0 required

Usage

A quick guide to implement a tcp echo client

Client:

`js
const TCPBase = require('tcp-base');

/**
* A Simple Protocol:
* (4B): request id
* (4B): body length
* ------------------------------
* body data
*/
class Client extends TCPBase {
getHeader() {
return this.read(8);
}

getBodyLength(header) {
return header.readInt32BE(4);
}

decode(body, header) {
return {
id: header.readInt32BE(0),
data: body,
};
}

// heartbeat packet
get heartBeatPacket() {
return Buffer.from([ 255, 255, 255, 255, 0, 0, 0, 0 ]);
}
}

const client = new Client({
host: '127.0.0.1',
port: 8080,
});

const body = Buffer.from('hello');
const data = Buffer.alloc(8 + body.length);
data.writeInt32BE(1, 0);
data.writeInt32BE(body.length, 4);
body.copy(data, 8, 0);

client.send({
id: 1,
data,
timeout: 5000,
}, (err, res) => {
if (err) {
console.error(err);
}
console.log(res.toString()); // should echo 'hello'
});
`

Server:

`js
'use strict';

const net = require('net');

const server = net.createServer(socket => {
let header;
let bodyLen;

function readPacket() {
if (bodyLen == null) {
header = socket.read(8);
if (!header) {
return false;
}
bodyLen = header.readInt32BE(4);
}

if (bodyLen === 0) {
socket.write(header);
} else {
const body = socket.read(bodyLen);
if (!body) {
return false;
}
socket.write(Buffer.concat([ header, body ]));
}
bodyLen = null;
return true;
}

socket.on('readable', () => {
try {
let remaining = false;
do {
remaining = readPacket();
}
while (remaining);
} catch (err) {
console.error(err);
}
});
});
server.listen(8080);
``

MIT