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Luigi Smith
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My understanding that when you cluster WebSphere servers, you have the option to essentially use one JVM that can span across several physical servers. To that end, can you access both read/write methods of CMPs deployed in the JVM via local interfaces, correct? An article I was reading said that you can only access read methonds in CMPs.
Also, how does the WLM come into play here? Any resource would be greatly appreciated.
TIA!
 
Kyle Brown
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Originally posted by Luigi Smith:
My understanding that when you cluster WebSphere servers, you have the option to essentially use one JVM that can span across several physical servers. To that end, can you access both read/write methods of CMPs deployed in the JVM via local interfaces, correct? An article I was reading said that you can only access read methonds in CMPs.
Also, how does the WLM come into play here? Any resource would be greatly appreciated.
TIA!

That's not the way it works. It's not one JVM that spans multiple servers, it multiple identical JVMs linked together through WLM. Thus, local interfaces are of no use to you. All of this is covered in my book, or in the Administration Handbook redbook.
Kyle
 
Luigi Smith
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Ok, so is the article correct in that you can only access read-only methods? Even in the way you described it, I don't see why that would preclude me from using all my exposed methods that are available on the remote interface, regardless if they are read/write.
I swear I've heard in the past of spanning JVM across servers (maybe the was an over-simplification of WLM), essentially treating the physical servers as a grid. Is this something IBM is working on or part of Enterprise edition? Just curious.
TIA!
 
Kyle Brown
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Originally posted by Luigi Smith:
Ok, so is the article correct in that you can only access read-only methods? Even in the way you described it, I don't see why that would preclude me from using all my exposed methods that are available on the remote interface, regardless if they are read/write.
I swear I've heard in the past of spanning JVM across servers (maybe the was an over-simplification of WLM), essentially treating the physical servers as a grid. Is this something IBM is working on or part of Enterprise edition? Just curious.
TIA!

No, you can call write methods remotely with WLM as well. This article basically sounds like a load of ****. Would you mind posting the link? And no, we're not working on anything that amounts to a single JVM spanning servers, trust me.
Kyle
 
Luigi Smith
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Thanks Kyle for the clarification.
The article was in the April edition of JDJ, "Scalability of J2EE Applications" by Stefan Pieshe, and I quote: "...some application servers (WLS6, Websphere) do not support Entity Bean clustering/caching in clustered infrastructures. In other words, they often support only the caching of read-only entity beans if you run a cluster, which rules straight CMP out completely to increase scalability." (pp. 26 April 04)
It's actually a decent article, but I thought this statement was misguided.
 
Kyle Brown
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That's a horribly misworded sentence. What I think they mean (which is, by the way, no longer true...) is that up until WebSphere 5.1 we didn't support Entity Bean Option A caching in a clustered environment, or more precisely, strongly advised against it if the values of your beans could change.
We now have an update API that uses our dynamic caching mechanism that can allow you to use Option A within a cluster.
Kyle
 
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