Saturday, March 01, 2003

JMX clustering

I don't like session clustering for a lot of reasons. Clustering in general is great - but the servlet session API just doesn't have enough power to allow a correct and efficient use of clustering. The use case for caching some values is compromised,

there is no transaction support, no feedback or control - users are much better served by assuming the session is transient, and using database or user-controled clustering.

By clustering I understand broadcasting and mirroring some data on multiple instances - there are many other meanings. It is a very powerful tool if used right.

There is one use of clustering that would be extremely intersting - broadcasting and clustering the JMX attributes. The idea is to have a global view - each tomcat instance could brodacast its mbeans and attributes, and may be able to take more inteligent decisions knowing the state of the other instances. And the admin console would get info from all instances.

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