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Node DDP Client

A callback style DDP (Meteor's Distributed Data Protocol) node client, originally based

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

Installation

$ npm install ddp-client

Authentication

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

One can authenticate using plain-text logins as follows:

// 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) { ... });

var DDPClient = require("ddp-client");

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
  // Use a full url instead of a set of `host`, `port` and `ssl`
  url: 'wss://example.com/websocket'
  socketConstructor: WebSocket // Another constructor to create new WebSockets
});

/*
 * 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();

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

Inspired by https://github.com/oortcloud/node-ddp-client