Setting Context Attribute in Clustered Environment

[Alec Lee]

If there is a cluster of web containers, there should be 1 separate ServletContext instance per JVM. And, if we do a servletContext.setAttribute(), would that attribute auto populated to another JVM?

[Ben Souther]

There is nothing in the spec to mandate this.

Tomcat has session replication but nothing for context scoped objects.
Other servers may have a proprietary solution for this.
[ February 09, 2006: Message edited by: Ben Souther ]

[Alec Lee]

Does that mean in Tomcat, after we've set an context attribute in one servlet, there is no guarantee that another servlet can get it back - because the second servlet may be executed in another JVM?

[dema rogatkin]

It looks like. So, some people recommend to use database for storing attributes.

[Ben Souther]

Originally posted by Alec Lee:
Does that mean in Tomcat, after we've set an context attribute in one servlet, there is no guarantee that another servlet can get it back - because the second servlet may be executed in another JVM?

Yes.
Context scope is useful for caches, and global, reaonly attributes that get set when the application loads but not necessarily a good place to store request time generated values in a clustered environment.