Using_Pubsub.md

Using PubSub

1. Create stanza definitions for our pubsub content

There are several existing payload formats that you can use, notably json, tune, avatar, and geoloc.

To create your own, the first step is to make a plugin for JXT to register the new stanza content:

var MyContentPlugin = function (client, stanza) {
    var types = stanza.utils;

    var MyContent = stanza.define({
        name: 'mypubsubcontent',
        namespace: 'http://example.org/mypubsub',
        element: 'stuff',
        fields: {
            value: types.text()
        }
    });

    // We want the content to be available for both publishing, and receiving update events.
    stanza.withPubsubItem(function (Item) {
        stanza.extend(Item, MyContent);
    });
});

We can then load the plugin with:

client.use(MyContentPlugin);

2. Publishing our new content

client.publish('pubsub.example.com', 'ournode', {
    mypubsubcontent: {
        value: 'Away it goes!'
    }
}, cb);

If you wanted to go a simpler, built-in route, you could use:

client.publish('pubsub.example.com', 'ournode', {
    json: {
        value: 'Any JSON content could go here'
    }
}, cb);

3. Subscribing to our content

client.subscribeToNode('pubsub.example.com', 'ournode', function (err) {
   if (!err) {
      console.log('subscribed');
   }
});

4. Receiving events

client.on('pubsub:event', function (msg) {
    if (!msg.event.updated) {
        // Ignore node purge/deletion/etc events.
        return;
    }

    if (msg.event.updated.node !== 'ournode') {
        // We only want the event for a specific node.
        return;
    }

    // Extract the published item and emit a simpler event
    client.emit('mypubsubcontent', {
        jid: msg.from,
        mypubsubcontent: msg.event.updated.published[0].mypubsubcontent
    });
});

5. Unsubscribing

client.unsubscribeFromNode('pubsub.example.com', 'ournode', function (err) {
   if (!err) {
      console.log('unsubscribed');
   }
});