Mosca error on publish - TypeError: Argument must be a string

[ldstein]

Hi,

I'm currently testing Mosca and having a problem getting it to play nice with MongoDB.

On publishing to a subscribed client, the broker fails with the following error:

/usr/local/bin/node Server/app.js
Server ready

/home/leo/test/Server/node_modules/mosca/node_modules/mqtt/lib/generate.js:178
    length += Buffer.byteLength(payload);
                     ^
Published { cmd: 'publish',
  retain: false,
  qos: 0,
  dup: false,
  length: 28,
  topic: 'heartbeat',
  payload: <Buffer 74 69 6d 65 31 33 38 33 32 31 37 33 38 32 39 33 32> }
TypeError: Argument must be a string
    at Object.module.exports.publish (/home/leo/test/Server/node_modules/mosca/node_modules/mqtt/lib/generate.js:178:22)
    at MqttServerClient.eval [as publish] (eval at <anonymous> (/home/leo/test/Server/node_modules/mosca/node_modules/mqtt/lib/connection.js:58:29), <anonymous>:2:26)
    at Client.actualSend (/home/leo/test/Server/node_modules/mosca/lib/client.js:142:21)
    at Client.forward (/home/leo/test/Server/node_modules/mosca/lib/client.js:198:10)
    at Array.handler [as 0] (/home/leo/test/Server/node_modules/mosca/lib/client.js:347:10)
    at EventEmitter.TrieAscoltatore.publish (/home/leo/test/Server/node_modules/mosca/node_modules/ascoltatori/lib/trie_ascoltatore.js:52:11)
    at EventEmitter.newPublish (/home/leo/test/Server/node_modules/mosca/node_modules/ascoltatori/lib/abstract_ascoltatore.js:122:20)
    at /home/leo/test/Server/node_modules/mosca/node_modules/ascoltatori/lib/mongo_ascoltatore.js:202:29
    at process._tickCallback (node.js:415:13)

Process finished with exit code 8

Any pointers on where I might be going astray? To confirm, this error only occurs when configuring a MongoDB backend. I'm testing with Node v0.10.21 in both Windows x64 and Ubuntu - results are consistent.

Below are my server/client.js I am using for testing.

server.js:

var mosca = require('mosca');

var serverConfig =
{
    mosca:
    {
        port: 1883,
        backend:
        {
            type: 'mongo',
            uri: 'mongodb://localhost:27017/',
            db:  'mqtt',
            pubsubCollection: 'ascoltatori',
            mongo: {}
        }
    }
}

var server = new mosca.Server(serverConfig.mosca);

server.on('ready'    , function(){
    console.log('Server ready');
});

server.on('published', function(packet, client){
    console.log('Published', packet);
});

client.js:

var mqtt = require('mqtt');

var client = mqtt.createClient(1883, 'localhost');

var handleConnect = function()
{
    console.log('Connected to mqtt broker with ClientId:', client.options.clientId);
    client.on('message', handleMessage);

    client.subscribe('heartbeat');
    client.publish('heartbeat', 'time' + new Date().getTime());
}

var handleMessage = function(topic, message, packet)
{
    console.log('Received Message');
    console.log('topic:', topic, 'message', message);
}

client.on('connect', handleConnect);

[mcollina]

Nice catch!

The problem is that the Buffer coming out of MongoDB is not recognized as a node Buffer object by bops.is in https://github.com/adamvr/MQTT.js/blob/master/lib/generate.js#L176-L181.

I solved the very same problem there: https://github.com/mcollina/mosca/blob/master/lib/persistence/mongo.js#L249.

I think the best solution is to solve it inside the MongoAscoltatore (which is the component that handles MongoDB pub/sub): https://github.com/mcollina/ascoltatori.

Are you in very urgent need for this? Can you do a pull-request against ascoltatori?
I can fix this in a couple of days.

[mcollina]

Can you please try moscajs/ascoltatori#85 and see if it solves the problem for you?

[ldstein]

Looking good, Mongodb is indeed working nicely now.

Many thanks!

[mcollina]

Opening up, as that one is not release yet.