Last updated $Date: 2000/02/21 15:01:39 $ $Author: ruff $

The HTTP callback framework for xmlBlaster

NOTE: This framework is work in progress, it is not yet finished for a production release.

What is this?

When distributing dynamic content over the internet, you usually choose an applet. The applet connects to the server over CORBA (or any other protocol) and may receive instant notification from the server.
But applets produce some well known problems like higher download time, firewalls which won't allow TCP/IP connections etc.

This framework addresses these issues. It establishes a persistent http connection to allow instant callbacks of xmlBlaster messages to the browser.

How does it work?

The servlet connects to xmlBlaster using CORBA and to the browser using a persistent http connection (using a hidden frame to communicate).

The messages are directly transferred to the browser, which has a Javascript based XML parser and notifies the interested browser frames about the callback.
The contentFrame and controlFrame in the picture are only an example, you can provide as many own frames as you wish. This is the work which is left for you to design your web layout.
The hidden callbackFrame is always necessary to handle the communication.

For Servlet and Javascript examples have a look into the following directory of the xmlBlaster distribution:

xmlBlaster/src/java/org/xmlBlaster/protocol/http
You need to access xmlBlaster with cvs or through cvsweb for these enhancements. The 0.73 release doesn't contain this code yet.

Please remember, the code is at most alpha.

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