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Detecting eviction events on a WebSphere extreme Scale client

Posted by: Billy Newport on

I've just pushed another sample to github. This sample shows how to attach a listener to the grid which watches transactions involved a set of maps. Any eviction events in those maps are 'noticed' and an eviction event is inserted in to a map thats basically used like a simple queue. I wrote a client side listener that can be attached to a client grid reference. This listener polls the server side grid looking for these events and returns them to the client.

The particular use case that prompted this sample was a customer using the grid to store application sessions and they needed a way for applications to be notified when the grid evicted their sessions. They wanted EVERY application JVM to see EVERY eviction. This is important to realize. Every eviction event will be processed by every application JVM instance. If we just needed the eviction event to be handled by exactly one application JVM then I'd write it using the getNextKey function in WXS.

The test package has sample objectgrid.xml and deployment.xml files as well as a test case showing how to invoke the client to test it.

Billy Newport's complete blog can be found at: http://www.devwebsphere.com/devwebsphere

About Billy Newport

Billy is a Distinguished Engineer at IBM. He's been at IBM since 2001. Billy was the lead on the WorkManager/ Scheduler APIs which were later standardized by IBM and BEA and are now the subject of JSR 236 and JSR 237. Billy lead the design of the WebSphere 6.0 non blocking IO framework (channel framework) and the WebSphere 6.0 high availability/clustering (HAManager). Billy currently works on WebSphere XD and ObjectGrid. He's also the lead persistence architect and runtime availability/scaling architect for the base application server.

Before IBM, Billy worked as an independant consultant at investment banks, telcos, publishing companies and travel reservation companies. He wrote video games in C and assembler on the ZX Spectrum, Atari ST and Commodore Amiga as a teenager. He started programming on an Apple IIe when he was eleven, his first programming language was 6502 assembler.

Billys current interests are lightweight non invasive middleware, complex event processing systems and grid based OLTP frameworks.

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