New Features in Strophe 1.0

January 8, 2010

On January 1st, 2010, Strophe 1.0 was released. This release included several new features that I haven’t talked about before, so I wanted to make sure they got some attention. These features are the ability to match on bare JIDs in handlers and to flush pending outgoing data immediately to the connection manager.

Matching Bare JIDs

The addHandler() function has always performed exact matching on its criteria. If you specified that your handler should match a stanza with a from attribute of darcy@pemberley.lit, then it would fail to match against a stanza with a from attribute of darcy@pemberley.lit.

Sometimes this is exactly the behavior your want, but it can also get in the way when you care only about the bare JID. Your application may not care what the resource portion of the JID is set to and needs only to check that the origin is as expected. One example would be to match incoming chat messages for a user regardless of which connection they are from.

Previously, you could accomplish this by setting your handler criteria to null and doing the extra check yourself within the handler. Now you can have the Strophe matching logic take care of this tedious task for you:

// connection is the Strophe.Connection instance
connection.addHandler(my_handler, null, 'message', null, null,
                      'darcy@chat.pemberley.lit`, {matchBare: true});

</code>

The addHandler() function now takes a new, optional seventh argument consisting of a dictionary of options. The only option currently supported is matchBare, which defaults to false and controls whether the JID matching is done on full or bare JIDs.

my_handler() will now be invoked for <message> stanzas with a from attribute of darcy@pemberley.lit, darcy@pemberley.lit/library, or even darcy@pemberley.lit/longbourn. This makes the handlers much simpler.

Flushing Data

Strophe is designed for high performance by default, and to this end, it queues outgoing data sent to the send() function until the next idle period, which will occur after 100 milliseconds.

The benefit of this delay is that if you call send() many times in the same handler or in the same chain of functions invoked from a handler, all this data will end up in a single HTTP request to the connection manager. If we sent all data immediately, each stanza would be sent in its own request. The small idle period is short enough that this causes little noticeable delay.

However, there are times when you want to force the data to be sent immediately, and before version 1.0, this was not possible in Strophe. The most common example is when you want to do some cleanup when the user navigates away from your application. If you simply put the cleanup code in the onbeforeunload event handler, the browser will invoke the code and then immediately tear down the JavaScript environment before the idle timer has a chance to fire. The cleanup stanzas would never get sent!

Strophe now includes the flush() function which forces all pending data to be sent immediately. Just call connection.flush() at the end of your handler, or whenever your code needs a new HTTP request to be sent. This fixes the problem of graceful tear-down in browsers, but it also allows you to eke out a little bit more performance in terms of low latency by using flush() to tell Strophe when your code done generating data.

As with most projects, these features were suggested by the kind Strophe community. Strophe would not be what it is without your help, feedback, and support. I hope you enjoy them!