bellhop

Description

A node.js module that exposes streams for doing Pubsub and RPC.

Requirements

• node.js -- v0.10.0 or newer

Install

npm install bellhop

Examples

• Simple RPC (no intermediate medium/stream):

var RPC = require('bellhop').RPC;

var RPC_Server = new RPC(),
    RPC_Client = new RPC();

RPC_Server.add(function add(a, b) {
  var cb = arguments[arguments.length - 1];
  cb && cb(a + b);
});
RPC_Server.add(function serverDate() {
  var cb = arguments[arguments.length - 1];
  cb && cb(new Date());
});
RPC_Server.add(function customCalc(fn) {
  var cb = arguments[arguments.length - 1];
  cb && cb(fn());
});


var add = RPC_Client.generate('add'),
    serverDate = RPC_Client.generate('serverDate'),
    customCalc = RPC_Client.generate('customCalc');

add(5, 5, function(err, result) {
  console.log('add() result = ' + result);
});
serverDate(function(err, date) {
  console.log('serverDate() date UNIX timestamp: ' + date.getTime());
});
customCalc(function() {
  console.log('Look at me, I am running on the server!');
}, function(err) {
  console.log('customCalc() Finished executing function on server');
});


RPC_Client.pipe(RPC_Server).pipe(RPC_Client);


// Example output:
//
// add() result = 10
// serverDate() date UNIX timestamp: 1383242166000
// Look at me, I am running on the server!
// customCalc() Finished executing function on server

• RPC over HTTP (10 simultaneous requests to same RPC server stream using Conveyor):

var http = require('http');
var Conveyor = require('conveyor'),
    RPC = require('bellhop').RPC;

var RPC_Server = new RPC(),
    c = new Conveyor(RPC_Server);

RPC_Server.add(function multiply(a, b) {
  var cb = arguments[arguments.length - 1];
  cb && cb(a * b);
});

var TOTAL = 10, count = 0;

http.createServer(function(req, res) {
  if (++count === TOTAL)
    this.close();
  c.push(req, res);
}).listen(8080, function() {
  console.log('HTTP RPC server listening');

  for (var i = 0; i < TOTAL; ++i) {
    (function(n) {
      var RPC_Client = new RPC(),
          multiply = RPC_Client.generate('multiply'),
          req = http.request({
            host: '127.0.0.1',
            port: 8080,
            method: 'POST'
          }, function(res) {
            res.pipe(RPC_Client, { end: false });
          });
      RPC_Client.pipe(req);
      multiply(2, n, function(err, result) {
        console.log('Result = ' + result);
        req.end();
      });
    })(i);
  }
});

// Output:
//
// HTTP RPC server listening
// Result = 0
// Result = 2
// Result = 4
// Result = 6
// Result = 8
// Result = 10
// Result = 12
// Result = 14
// Result = 16
// Result = 18

• Simple Pubsub (no intermediate medium/stream):

var Pubsub = require('bellhop').Pubsub;

var Pubsub1 = new Pubsub(),
    Pubsub2 = new Pubsub();

Pubsub1.events.on('today', function(date) {
  console.log('Today is: ' + date);
});

Pubsub2.events.emit('today', new Date());

Pubsub1.pipe(Pubsub2).pipe(Pubsub1);

// Example output:
//
// Today is: Thu Oct 31 2013 14:02:00 GMT-0400 (Eastern Daylight Time)

• Simple Pubsub over TCP:

var net = require('net');

var Pubsub = require('bellhop').Pubsub;

var PubsubRecvr = new Pubsub(),
    PubsubSender = new Pubsub();

net.createServer(function(sock) {
  this.close();
  PubsubSender.pipe(sock);
  PubsubSender.events.emit('today', new Date());
}).listen(9000, '127.0.0.1');

var sock = new net.Socket();
sock.pipe(PubsubRecvr);
PubsubRecvr.events.on('today', function(date) {
  console.log('Today is: ' + date);
  sock.end();
});
sock.connect(9000, '127.0.0.1');

// Example output:
//
// Today is: Thu Nov 14 2013 07:52:01 GMT-0500 (Eastern Standard Time)

• RPC AND Pubsub over the same TCP socket:

var net = require('net');

var Pubsub = require('bellhop').Pubsub,
    RPC = require('bellhop').RPC;

var rpcServer = new RPC(),
    rpcClient = new RPC(),
    pub = new Pubsub(),
    sub = new Pubsub();

rpcServer.add(function foo() {
  console.log('Got RPC');
});

sub.events.on('bar', function() {
  console.log('Got event');
});

net.createServer(function(sock) {
  this.close();
  sock.pipe(rpcServer);
  sock.pipe(sub);
}).listen(9000, '127.0.0.1');

var sock = new net.Socket();
rpcClient.pipe(sock);
pub.pipe(sock);

sock.connect(9000, '127.0.0.1', function() {
  rpcClient.generate('foo')();
  pub.events.emit('bar');
  sock.end();
});

// Output:
//
// Got RPC
// Got event

Benchmarks

Benchmarks can be found in bench/.

Pubsub benchmark (as of 11/14/2013) for Core i7-3770k, Windows 7 x64, node v0.10.22:

50000 events (no args): 327ms
50000 events (3 short strings): 389ms
50000 events (3 longer strings): 433ms
50000 events (3 regexps): 654ms
50000 events (3 functions): 874ms
50000 events (5 numeric values): 470ms

API

All types are Duplex streams.

RPC methods

• (constructor)([< object >options]) - Creates and returns a new RPC instance with the following valid options:

  • serialize - boolean - Manually serialize objects that JSON does not support (well)? (Default: true).

  • ignoreInvalidCall - boolean - Do not send error responses to incoming function call requests for invalid methods (Default: false).

  • highWaterMark - integer - High water mark to use for this stream (Default: Duplex stream default).

• generate(< string >remoteFuncName) - function - Returns a function that can be used when calling a particular remote function. This makes things easier than using send() manually. The return value of the returned function is similar to that of Writable.write() and indicates if the high water mark has been reached.

• send([< mixed >arg1, ..., < mixed >argn, ]< string >remoteFuncName[, < function >callback]) - (boolean) - Calls the function identified by remoteFuncName (with optional arguments). The return value is similar to that of Writable.write() and indicates if the high water mark has been reached.

• add(< function >method[, < string >methodName]) - (void) - Adds a function that can be called by others. methodName is optional if method is a named function, however you can always override the name with methodName. The last argument passed to the function is the callback to call in case the other side requested a response. The return value of the callback is similar to that of Writable.write() and indicates if the high water mark has been reached.

• remove([< function >method][, < string >methodName]) - (void) - Removes a function previously added via add(). The removal process first checks methodName, then method for a name, and if those two are not set then all instances of that function are removed.

Pubsub properties

• events - EventEmitter - This is the event emitter object used to emit events to others and to receive events from others.

Pubsub (special) events

• *(< mixed >event[, < mixed >arg1, ..., < mixed >argn]) - Emitted for every event for use as a "catch-all."

Pubsub methods

• (constructor)([< object >options]) - Creates and returns a new Pubsub instance with the following valid options:

  • serialize - boolean - Manually serialize objects that JSON does not support (well)? (Default: true).

  • highWaterMark - integer - High water mark to use for this stream (Default: Duplex stream default).

Notes

• Serialization of types unsupported by JSON is an option and is enabled by default.

• Properties of "non-plain objects" (e.g. Dates, Functions, Errors, RegExps) are not checked for needed serialization.

• Circular references are not detected.

• RPC-specific:

  • Callback functions follow the error-first argument pattern. Any arguments after the error argument are values returned by the other side.

  • All functions returned by generate() will assume that a function passed as the last argument will be a callback to be executed when the server responds. If you need to pass a function to the other side, make sure a non-function value separates it and the optional callback OR you can use send() directly instead. Examples:

    // ....
    var map = RPC_Client.generate('map');
    
    // no callback/response (THIS IS WRONG, the mapper function will not be sent to the other side and will be used as a callback instead)
    map([0, 1, 2, 3, 4], function(n) { return n * 2; });
    
    // no callback/response
    map(function(n) { return n * 2; }, [0, 1, 2, 3, 4]);
    
    // callback/response requested
    map(function(n) { return n * 2; }, [0, 1, 2, 3, 4], function(result) { console.log('Result: ' + result); });
    
    // OR always use `send()` directly if you want/need the mapper function to always be the second argument:
    
    // no callback/response
    RPC_Client.send([0, 1, 2, 3, 4], function(n) { return n * 2; }, 'map');
    
    // callback/response requested
    RPC_Client.send([0, 1, 2, 3, 4], function(n) { return n * 2; }, 'map', function(result) {
      console.log('Result: ' + result);
    });