TCP Client

Factory for creating TCP clients.

Installation

$ npm install flow-tcp-client

For use in the browser, use browserify.

Usage

To create a TCP client,

var createClient = require( 'flow-tcp-client' );

var client = createClient();

TCP clients are configurable and have the following methods...

client.host( [host] )

This method is a setter/getter. If no host is provided, the method returns the configured host. By default, the client host is 127.0.0.1. To point to a remote host,

client.host( '192.168.92.11' );

client.port( [port] )

This method is a setter/getter. If no port is provided, the method returns the configured port. By default, the client port is 7331. To set a port,

client.port( 8080 );

client.connect()

Creates a TCP socket connection.

client.connect();

client.status()

Returns the current connection status. If a socket connection exists, returns true. If no socket connection exists, returns false.

client.status();

client.strict( [bool] )

This method is a setter/getter. If no boolean flag is provided, the method returns the strict setting. By default, the socket enforces strict type checking on socket writes. To turn off strict mode,

client.strict( false );

client.write( string[, clbk] )

Writes to a socket connection. If strict mode is off, no type checking of input arguments occurs. An optional callback is invoked after writing data to the socket. To write to the socket,

var data = {
		'value': [ Date.now(), Math.random() ]
	};

data = JSON.stringify( data ) + '\n';

client.write( data, function ack() {
	console.log( '...data written...' );
});

client.stream()

Returns a socket stream.

var stream = client.stream();

Note: in order to return a socket stream, a socket connection must first be established.

Additionally, note that the returned stream conforms to the Node.js stream interface.

var eventStream = require( 'event-stream' );

// Create some data:
var data = [ 'beep\n', 'boop\n', 'bop\n', 'bip\n', 'bap\n' ];

// Create a readable stream:
var readStream = eventStream.readArray( data );

// Get the client stream:
var socketStream = client.stream();

// Pipe the data...
readStream.pipe( socketStream );

client.end()

Closes a socket connection. To close a socket,

client.end();

Events

'connect'

The client emits a connect event upon successfully establishing a socket connection. To register a listener,

client.addListener( 'connect', function onConnect() {
	console.log( '...connected...' );
});

'error'

The client emits an error event upon encountering an error. To register a listener,

client.addListener( 'error', function onError( error ) {
	console.error( error.message );
	console.error( error.stack );
});

'close'

The client emits a close event when the other end of the connection closes the socket. To register a listener,

client.addListener( 'close', function onClose() {
	console.log( '...socket closed...' );
	console.log( '...attempting to reconnect in 5 seconds...' );
	setTimeout( function reconnect() {
		client.connect();
	}, 5000 );
});

'warn'

The client emits a warn event when attempting to create a new socket connection when a connection already exists. To register a listener,

client.addListener( 'warn', function onWarn( message ) {
	console.warn( message );
});

Notes

When used as setters, all setter/getter methods are chainable. For example,

var createClient = require( 'flow-tcp-client' ),
	client = createClient();

client
	.host( '192.168.92.111' )
	.port( 8080 )
	.strict( false )
	.connect();

Examples

var createClient = require( 'flow-tcp-client' );

var client = createClient();

client
	.host( '192.168.92.111' )
	.port( 4243 )
	.strict( false );

client.on( 'error', onError );
client.on( 'close', onClose );
client.on( 'connect', onConnect );

connect();

function connect() {
	client.connect();
}

function onError( error ) {
	console.error( error.message );
	console.error( error.stack );
}

function onClose() {
	console.log( '...attempting to reconnect in 2 seconds...' );
	setTimeout( function reconnect() {
		connect();
	}, 2000 );
}

function onConnect() {
	for ( var i = 0; i < 100; i++ ) {
		write( i );
	}
}

function write( idx ) {
	setTimeout( function onTimeout() {
		if ( client.status() ) {
			client.write( newLine(), onWrite );
		}
	}, 1000*idx );
}

function newLine() {
	var time = Date.now(),
		val = Math.random(),
		data;

	data = {
		'value': [ time, val ]
	};

	return JSON.stringify( data ) + '\n';
}

function onWrite() {
	console.log( '...data written to socket...' );
}

To run the example code from the top-level application directory,

$ node ./examples/index.js

Tests

Unit

Unit tests use the Mocha test framework with Chai assertions. To run the tests, execute the following command in the top-level application directory:

$ make test

All new feature development should have corresponding unit tests to validate correct functionality.

Test Coverage

This repository uses Istanbul as its code coverage tool. To generate a test coverage report, execute the following command in the top-level application directory:

$ make test-cov

Istanbul creates a ./reports/coverage directory. To access an HTML version of the report,

$ open reports/coverage/lcov-report/index.html

License

MIT license.

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Copyright

Copyright © 2014. Athan Reines.