Tomcat 6.0 comet support and asynchronous servlets

Comet support allows a servlet to process IO asynchronously, recieving events when data is available for reading on the connection , and writing data back on connections asynchronously.

Comet applications can deliver data to the client at any time, not only in response to user input. The data is delivered over a single, previously-opened connection. This approach reduces the latency for data delivery significantly.

Tomcat 6.0 comet support

Servlets which implement the org.apache.catalina.CometProcessor interface will have their event method invoked rather than the usual service method, according to the event which occurred.

• EventType.BEGIN: will be called at the beginning of the processing of the connection.
• EventType.READ: This indicates that input data is available, and that one read can be made without blocking.
• EventType.END: End may be called to end the processing of the request.
• EventType.ERROR: Error will be called by the container in the case where an IO exception or a similar unrecoverable error occurs on the connection.

Similar to regular filters, a filter chain is invoked when comet events are processed. These filters should implement the CometFilter interface

Advanced IO and Tomcat
Comet: Low Latency Data for the Browser
Apache Tomcat Comet API Wiki
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