Asynchronous module: 100% AJAX Drupal

We have seen a lot of interest in making Drupal load content dynamically. This enables many use cases not currently possible. E.g.: on a past project, we have been asked to make a video player play continuous, while the user browses the site. On a Drupal 5 site, the only way to do this was using frames, and frames sucks.

Some improvements were done in Drupal 6 to pave the way for AJAX. We got dynamic form submissions (AHAH), jQuery forms library and javascript behaviors can now be re-attached. On the server side, however, things haven't achieved such maturity.

It has been a while since I've started to code a module with the ambitious purpose of making Drupal work 100% asynchronously. This is a challenging task, and this was the main motivation I had to give it a try. The result of this effort is Asynchronous module.

Besides all the coolness Asynchronous module provides, it also serves as a indicator of how ready Drupal is to do that kind of stuff, and to detect its flaws/limitations in order to propose some enhancements to Drupal 7 to make that task easier to accomplish.

The module is somewhat stable and usable, but not feature complete yet. It's known to work on Firefox 3 and Safari 3. It currently features dynamic loading of all pages elements (sidebars, primary/secondary links, footer) as well as page main content, form submition and browser history handling (back and forward buttons work!).

For the module to work, it requires a theme that implements asynchronous functionality. Currently only Chrysalis theme does this (support for core themes is planned). We need this, since asynchronous module relies on jQuery selectors to place dynamic loaded content, and since themes structure (css classes, ids, main content) vary between themes, we can't provide a single set of rules that will make it work across all themes.

Here is a report of what I felt Drupal core could do better:

First of all it's not an easy task to make Drupal render pages in other formats than html. The rendering/template system is somewhat hardcoded to produce pages in html. To make pages render in JSON format as required by asynchronous module, I have to implement hook_render_template() on behalf of phptemplate engine, since apparently there is no way modules can do this, only themes can.

Another tricky thing was the one I've come together in order to make drupal_goto() persist the requested renderer between page redirects, e.g. when submitting a form. I did this in a hook_exit() implementation, but since this doesn't allow you to alter the query string when redirecting, I had to direct redirect from there, using header(), skipping standard drupal_goto() redirect.

Not every Drupal behavior is really re-attachable, so there are still some things broken/partially broken. Things like fixed tableheader, and a few other behaviors can't really be added to dynamic loaded content. Also, color module will not work this way.

Client side code (javascript) limitations are often easy to workaround. But server side ones are sometimes infeasible.

Luckly, I was able to workaround all (or almost all) server side limitations, and this resulted in Page Renderer module, a module which Asynchronous module depends on.

The top enabler issue is Enable loading and rendering into JSON, XML, etc.

100% AJAX Drupal is possible and with a few improvements to core we can make it work clean and seamless.

Check out Asynchronous module demo!