XML in Mozilla 1.0 (2/2) - exploring XML
XML in Mozilla 1.0
Transport of XML
While the DOM functions provide powerful access to a document's structure and content, sending and receiving documents has also been implemented in Mozilla 1.0:
XMLHttpRequest and SOAP
Microsoft has introduced an XMLHttpRequest object into IE that allows for sending and receiving of XML documents over HTTP. This functioanlity has been mirrored in Mozilla as closely as possible. SOAP is also supported, as well as some parsing and serialization functions to be replaced by DOM level3.
Internal use of XML
XML is also used for internal tasks in Mozilla, such as storing bookmarks, describing the user interface, and attaching events to it:
All internal data is stored in RDF (Resource Description Framework). Mozilla uses RDF to aggregate and display information about things like email, news, site maps, bookmarks, and browser history.
The most widely publicized use of XML in Mozilla is XUL (the XML User Interface Language), used to describe Mozilla's own user interface. It is an elegant way of specifying UI where usually binary resource files are employed, but has also been criticized as the most bloated and overkill design decision in Mozilla. Many derivates of Mozilla use the Gecko rendering engine directly with a native widget set wrapped around it, losing a few megabytes and gaining a few seconds at program startup. The choice is yours, but the technology is neat in any case.
XBL is a companion to XUL for describing bindings that can be attached to elements in other documents through CSS or DOM. Such bindings can be used for dynamic manipulation of the behavior of elements, by attaching scripts to certain events and nodes. This is going in the same direction as Microsoft's behavior elements in CSS.
Waiting for Mozilla 1.0 has certainly paid off (and long did we wait...). It provides a rich document processing environment, with all content accessible through DOM functions, and manifold application development features through XUL and its programming APIs. It remains to be seen if significant numbers of surfers will now choose this new platform for interactive applications that go well beyond simple page display, or whether the 80% market share of Internet Explorer (at least on this Web site) teaches Mozilla: Not too little, but much too late...
Produced by Michael Claßen
Created: Jun 24, 2002
Revised: Jun 24, 2002