ddp

Node DDP Client
===============

A callback style DDP (Meteor's Distributed Data Protocol) node client, originally based alansikora's node-js_ddp-client and Meteor's python client. Uses a more callback style approach.

The client implements version 1 of DDP, as well as fallbacks to pre1 and pre2.

Installation
============

``
npm install ddp
`

Authentication
==============
Built-in authentication support was removed in ddp 0.7.0 due to changes in Meteor version 0.8.2.

DDP Authentication is now implemented by vsivsi/ddp-login.

A quick and dirty (but insecure) alternative is to use plain-text logins via a method call:

`js
// logging in with e-mail
ddpclient.call("login", [
{ user : { email : "user@domain.com" }, password : "password" }
], function (err, result) { ... });

// logging in with username
ddpclient.call("login", [
{ user : { username : "username" }, password : "password" }
], function (err, result) { ... });
`


Example
=======

Please see the example in examples/example.js. Or here for reference:

`js
var DDPClient = require("ddp");

var ddpclient = new DDPClient({
// All properties optional, defaults shown
host : "localhost",
port : 3000,
ssl : false,
autoReconnect : true,
autoReconnectTimer : 500,
maintainCollections : true,
ddpVersion : '1', // ['1', 'pre2', 'pre1'] available
// uses the SockJs protocol to create the connection
// this still uses websockets, but allows to get the benefits
// from projects like meteorhacks:cluster
// (for load balancing and service discovery)
// do not use path option when you are using useSockJs
useSockJs: true,
// Use a full url instead of a set of host, port and ssl
// do not set useSockJs option if url is used
url: 'wss://example.com/websocket'
});

/*
* Connect to the Meteor Server
*/
ddpclient.connect(function(error, wasReconnect) {
// If autoReconnect is true, this callback will be invoked each time
// a server connection is re-established
if (error) {
console.log('DDP connection error!');
return;
}

if (wasReconnect) {
console.log('Reestablishment of a connection.');
}

console.log('connected!');

setTimeout(function () {
/*
* Call a Meteor Method
*/
ddpclient.call(
'deletePosts', // name of Meteor Method being called
['foo', 'bar'], // parameters to send to Meteor Method
function (err, result) { // callback which returns the method call results
console.log('called function, result: ' + result);
},
function () { // callback which fires when server has finished
console.log('updated'); // sending any updated documents as a result of
console.log(ddpclient.collections.posts); // calling this method
}
);
}, 3000);

/*
* Call a Meteor Method while passing in a random seed.
* Added in DDP pre2, the random seed will be used on the server to generate
* repeatable IDs. This allows the same id to be generated on the client and server
*/
var Random = require("ddp-random"),
random = Random.createWithSeeds("randomSeed"); // seed an id generator

ddpclient.callWithRandomSeed(
'createPost', // name of Meteor Method being called
[{ _id : random.id(), // generate the id on the client
body : "asdf" }],
"randomSeed", // pass the same seed to the server
function (err, result) { // callback which returns the method call results
console.log('called function, result: ' + result);
},
function () { // callback which fires when server has finished
console.log('updated'); // sending any updated documents as a result of
console.log(ddpclient.collections.posts); // calling this method
}
);

/*
* Subscribe to a Meteor Collection
*/
ddpclient.subscribe(
'posts', // name of Meteor Publish function to subscribe to
[], // any parameters used by the Publish function
function () { // callback when the subscription is complete
console.log('posts complete:');
console.log(ddpclient.collections.posts);
}
);

/*
* Observe a collection.
*/
var observer = ddpclient.observe("posts");
observer.added = function(id) {
console.log("[ADDED] to " + observer.name + ": " + id);
};
observer.changed = function(id, oldFields, clearedFields, newFields) {
console.log("[CHANGED] in " + observer.name + ": " + id);
console.log("[CHANGED] old field values: ", oldFields);
console.log("[CHANGED] cleared fields: ", clearedFields);
console.log("[CHANGED] new fields: ", newFields);
};
observer.removed = function(id, oldValue) {
console.log("[REMOVED] in " + observer.name + ": " + id);
console.log("[REMOVED] previous value: ", oldValue);
};
setTimeout(function() { observer.stop() }, 6000);
});

/*
* Useful for debugging and learning the ddp protocol
*/
ddpclient.on('message', function (msg) {
console.log("ddp message: " + msg);
});

/*
* Close the ddp connection. This will close the socket, removing it
* from the event-loop, allowing your application to terminate gracefully
*/
ddpclient.close();

/*
* If you need to do something specific on close or errors.
* You can also disable autoReconnect and
* call ddpclient.connect() when you are ready to re-connect.
*/
ddpclient.on('socket-close', function(code, message) {
console.log("Close: %s %s", code, message);
});

ddpclient.on('socket-error', function(error) {
console.log("Error: %j", error);
});

/*
* You can access the EJSON object used by ddp.
*/
var oid = new ddpclient.EJSON.ObjectID();
`

SockJS Mode
===============

By using the useSockJs option like below, DDP connection will use SockJs protocol to establish the WebSocket connection.

`js
var ddpClient = new DDPClient({ useSockJs: true });
`

Meteor server uses SockJs to implement it's DDP server. With this mode, we can get the benefits provided by meteorhacks:cluster. Some of those are load balancing and service discovery.

* For load balancing you don't need to anything.
* For service discovery, just use the path option to identify the service you are referring to.

> With this mode, path option has a special meaning. So, thing twice before using path` option when you are using this option.

Unimplemented Features
====
The node DDP client does not implement ordered collections, something that while in the DDP spec has not been implemented in Meteor yet.

Thanks
======

Many thanks to Alan Sikora for the ddp-client which formed the inspiration for this code.

Contributions:
* Tom Coleman (@tmeasday)
* Thomas Sarlandie (@sarfata)
* Mason Gravitt (@emgee3)
* Mike Bannister (@possiblities)
* Chris Mather (@eventedmind)
* James Gill (@jagill)
* Vaughn Iverson (@vsivsi)