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From Costin Manolache <>
Subject Re: [5] Few major changes in JMX naming
Date Sun, 16 Mar 2003 22:26:00 GMT
Glenn Nielsen wrote:

> I haven't looked at or played with the new JMX featuers.  But I do have
> some thoughts on names and scopes.  We need to ensure that there is a
> unique naming mechanism.

That's the intention of the change.

> A single monitoring tool may be used to monitor multiple instances of
> Tomcat.  I plan on doing that some time in the future.  Each instance
> of Tomcat running needs to have a unique name.

Well - I'm already working on the "JMX proxy" ( similar with the proxy for
mod_jk2 mbeans ). And /admin and any other tool will manage clusters ( or
multiple instances ) just like they manage a single instance.

For example, with a bit of cleanup, /admin could display a select box with
all the domains - and administer any tomcat instance ( assuming some setup
is done to proxy the JMX domains ) 

An essential piece is indeed the "unique name" - and in JMX terms that will
be the domain ( and will also be used as jvmRoute ).

> The host name can not be used in lieu of the Engine name.  I configure
> two Engine's which have the same host name.  One for normal http, one for
> https.

Host name has nothing to do with this. 

The JMX domain corresponds to one Engine. An Engine can contain multiple
hosts, and you can have multiple engines ( in different JMX domains ) and 
multiple connectors.

The Engine name is the id of a tomcat instance ( even if you run multiple 
Engines in the same JVM - from the point of view of routing or admin, they
are different )

> The scoping required to ensure unique names is
> /Service/Engine/Host/Context.

There is a one-to-one mapping between Service and Engine, and Embeded tomcat
doesn't use Service ( Service is just a wrapper for 1 Engine + Connectors ).

So the naming will be:
 Engine -> Host -> Context


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