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From Alex Blewitt <>
Subject Re: Dynamic MBeans. Was: Kernel Architecture
Date Wed, 13 Aug 2003 08:19:59 GMT

On Wednesday, Aug 13, 2003, at 08:35 Europe/London, Pasi Salminen wrote:

> At least I'm in favour of model MBeans. They can be described in XML 
> (which I think is a good idea) and they can have annotations. What 
> does it say to an administrator if he can see an operation stop? For 
> us (being professional J2EE propeller heads) it may be obvious but for 
> an administrator it would be nice to see some description of the 
> operation or attribute he is trying to invoke or manipulate. That's 
> why model beans are nice. And if the configuration file is implemented 
> so that it can "dig" information out of the bean (if not
> overridden in the XML configuration) that's cool and keeps 
> configuration simpler.

Bear in mind that a console doesn't have to be provided in terms of its 
coding interface. I have used another J2EE server where it is clear 
that everything is exposed from underlying MBeans, and the net effect 
is of a very disorganised and non-user-friendly UI.

> Secondly, I don't understand why some of you are so afraid of JMX. 
> Nobodys afraid of HTTP fading away. It's there in the spec and it'll 
> be part of the server anyhow, just like servlets.

I think that the big disadvantages of using JMX as a kernel is ...

> However, whoever has proposed JMX (kernel) to be used as an invocation 
> bus, I not sure if I agree with him/her. The MBeans could just expose, 
> for example the HTTP support, and from then on it just controls when 
> to stop it and how to get performance metrics (etc) from it. 
> Inter-service bindings/lookups could of course be implemented with JMX 
> relation service...

... the one you mentioned.

Plus, it does tend to take the discussions of the configuration file 
as: "Let's use XML to configure which MBeans to start up", which again 
may not be the most user-friendy way of providing the information to an 

You also run into further issues in the ConfigurationAsFlatFile and 
ConfigurationAsRegistry wiki pages, which I won't go into any more here.

> Alex.

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