CODEWITHSUNDEEP
javatomcatservlets
shrey
shrey

Reputation: 863

get servlet context variable data in tomcat cluster environment

Currently I am developing module to display list of online user in my application. I am using comet streaming technology. When users log in I put data in map and then sending data in message queue. Now message queue is stored in servlet context.

Now problem I am facing is it is working in local environment but it is not working in production environment because in production environment i have set up tomcat cluster. so data set in servlet context for tomcat 1 is not accessible in tomcat 2.

I have already develop module but not getting any way to solve above issue. I google and found that tomcat doesn't support context replication.

I have one doubt that how many JVM instance will be created in tomcat cluster web application. e.g I have two tomcat cluster.

Upvotes: 0

Views: 1184

Answers (2)

Serge Ballesta
Serge Ballesta

Reputation: 148910

I would not use servlet context to store data for a cluster. The common pattern is to use a database for data that must be shared across different servers.

For your use case, it is no need persisting the values between different runs, so the database is not necessarily a nice solution, even if it is easy to setup. IMHO what you need it just a shared data cache or better a memory data grid. hazelcast should be easy to use for your requirements. If I correctly understand them, what you need is a distributed map, with a concatenation of node_id, session_id as key (or maybe simply session_id), and a user object as value.

Upvotes: 1

Khary Mendez
Khary Mendez

Reputation: 1848

In tomcat7 this requires writing a custom valve to force replication, the same is true in tomcat 6. Refer to Is there a useDirtyFlag option for Tomcat 6 cluster configuration? to see how to do this.

Upvotes: 0

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