Primus Callbacks

Client and server plugin that adds a request/response cycle to Primus. This is a fork of primus-responder module with a secure request id generation (uuid generation RFC 4122 compliant) and a timeout for each request. Note: the current 2.x release is not backward compatible with the previous due the new signature of the writeAndWait method and the callback used as response (see below).

Installation

$ npm install primus-callbacks --save

Use cases

• Wrap existing REST API into a realtime websocket connection
• Simplify program flow if waiting on a specific response is needed

Usage

Use requestTimeout option to define a timeout for every request (both on server and client). If no response is received after requestTimeout ms, the callback is executed passing an Error instance with a timeout property (see test.js).

On the server

var Primus = require('primus')
  , PrimusCallbacks = require('primus-callbacks')
  , server = require('http').createServer()
  , options = {
      transformer: 'websockets',
      parser: 'JSON',
      requestTimeout: 10000
    }
  , primus = new Primus(server, options);

primus.use('callbacks', PrimusCallbacks);

primus.on('connection', function(spark) {

    // Handle incoming requests:
    spark.on('request', function(data, done) {
        // Echo the received request data
        done(null, data);
    });

    // Request a response from the spark:
    spark.writeAndWait('request from server', function(err, response) {
        // Write the sparks response to console
        console.log('Response from spark:' response);
    });

});

server.listen(8080);

On the client

Browser

var options = {
  transformer: 'websockets',
  parser: 'JSON',
  requestTimeout: 1000
};
var primus = Primus.connect('ws://localhost:8080', options);

// Handle incoming requests:
primus.on('request', function(data, done) {
    // Echo the received request data
    done(null, data);
});

// Request a response from the server:
primus.writeAndWait('request from client', function(err, response) {
    // Write the servers response to console
    console.log('Response from server:', response);
});

Node

var Primus = require('primus')
  , PrimusCallbacks = require('primus-callbacks')
  , options = {
    transformer: 'websockets',
    parser: 'JSON',
    requestTimeout: 1000,
    plugin: {
        callbacks: PrimusCallbacks
    }
  }
  , primus = new primus.Socket('ws://localhost:8080', options);

// Handle incoming requests:
primus.on('request', function(data, done) {
    // Echo the received request data
    done(null, data);
});

// Request a response from the server:
primus.writeAndWait('request from client', function(err, response) {
    // Write the servers response to console
    console.log('Response from server:', response);
});

API

Server

spark#on('request', fn)

Registers an event handler for incoming requests. The handler has two arguments: fn(data, done)

• data contains the data which was sent with the request
• done is a callback function. The signature is done (err, res), where:
  • err is the error if occurred (as an Error instance or String)
  • res is the the data you want to transmit.

spark.on('request', function(data, done) {
    done('this is an error', 'this is the response');
});

spark#writeAndWait(data, fn)

Sends data to the given spark. As soon as the response from the spark arrives, fn is called with the error if occurred and the sparks response as arguments: fn (err, res).

spark.writeAndWait('request data', function(err, res) {
    console.log('spark responded:', res);
});

Client

primus#on('request', fn)

Registers an event handler for incoming requests. The handler has two arguments: fn(data, done)

• data contains the data which was sent with the request
• done is a callback function. The signature is done (err, res), where:
  • err is the error if occurred (as an Error instance or String)
  • res is the the data you want to transmit.

primus.on('request', function(data, done) {
    done('this is an error', 'this is the response');
});

primus#writeAndWait(data, fn)

Sends data to the connected server. As soon as the response from the spark arrives, fn is called with the error if occurred and the sparks response as arguments: fn (err, res).

primus.writeAndWait('request data', function(err, res) {
    console.log('server responded:', response);
});

Run tests

You can test in Node environment simply typing:

$ npm test

To test in browser run:

$ node test/browser/server.js

and open test/browser/index.html in your browser.

License

Copyright (c) 2014 Yoovant by Marcello Gesmundo. All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

• Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
• Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
• Neither the name of Yoovant nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Copyright (c) 2013 Manuel Alabor

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

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