Open Source XML Application Server

June 23, 1999

Dale Dougherty

Planet 7 Technologies of Redmond, WA has released a beta version of its XML Application Server (XAS) under the Open Source licence. The XML Application Server is written in Java and requires a Java Virtual Machine.

The XML Application Server allows XML documents to be shared and modified in real-time by multiple users whose interactions with the document become part of the document. It is intended for interactive, collaborative applications, especially where monitoring user activity in real-time is important. contacted Chris Jones, the CEO of Planet 7 Technologies who along with business partner, Drew Batchelor, is the author of the upcoming Open Source Linux Web Programming (IDG Books). Here's what Jones told about using the XML Application Server:

The first step is to make an XML representation of your web site (obviously, this can be automated). The resultant XML document may have nodes representing each page, and perhaps even the content within them. This document is published to XAS ready for client access.

Using the XAS client tools (currently a Java-based API), a lightweight client component applet can be written in under 30 lines of code-- under 8K if you include the one-time download of the supporting classes. This component is scriptable using JavaScript, and communicates with the server. This applet can be placed in a hidden frame, accessible via JavaScript throughout the rest of your site.

All of the page-level events and DOM nodes you wish to track can call an applet-provided function in their onclick event, or whichever event is appropriate. As events fire, the applet sends a small XML message to the server, which updates the XML view of your site with the current user's page-level actions. This technique provides a real-time, XML view of your entire web-site and its concurrent visitors. Of course, since its XML, this real-time view can be consumed by any other application in your enterprise, whenever desired.

Some of the sample applications that have been developed with XAS include a simple online game, a whiteboard/chat application and a real-time site monitor. Jones also said that XAS can used as intelligent middleware between two XML sources. "In an enterprise with multiple, real-time XML data feeds, XAS can be used to merge the two together intelligently, and provide concurrent access to a myriad of clients, and other applications," he said.

XAS was released under the Open Source license, according to Jones, "to encourage the use of our server within the development community without worry of being locked into proprietary formats, or specific vendor support." The beta release will lead to a 1.0 Open Source release, sometime in the future.

The XML Application Server can be downloaded for Linux and Windows platforms from Planet 7 Technologies, if you can follow the Soylent-Green-colored pages to locate the download instructions.