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From Stephen McConnell <mcconn...@apache.org>
Subject Re: [MERLIN]How to get a global lookup for services?
Date Tue, 16 Dec 2003 18:31:57 GMT

Hi Peter:

See notes in-line.


pnb@scancoin.se wrote:

>Hi,
>we are looking a bit closer at the service configuration of Merlin. It seems
>that every component get's it's own ServiceManager that provides the
>declared dependencies to the component.
>
>Is there a way to look up components at runtime, e.g. by
>"container/component", that are not in the ServiceManager? 
>

No.

The keys handled by the the service manager are aligned directly with 
the @avalon.dependency tags for the component to which the service 
manager is assigned.

>Or is JNDI etc. used for that?
>
>It seems that in the block.xml you can only override already declared
>dependencies, not insert any new ones?
>

Correct.

If you were inserting new deependecies - you would do this at the level 
of the type (i.e. under the xinfo - or equivalent @avalon.dependency). 
If your component needs to aquire something dynamic - then your 
component should be declaring a dependency on some application specific 
finder service.  The implementation of that finder service could do some 
intertesting things with an embedded kernel - but that's another thread.

>How can you add a dependency after the SM is finished (e.g. when the
>configuration on a component is called?)
>

You cannot - you can only get the depedency you declare at the level of 
the type.
This is intentional - if you want to step outside of this constraint you 
need to be thinking about a service that provides the discovery 
semantics that you are thinking of.

What is the "discovery scenario" your dealing with?

Cheers, Steve.


>
>Thanks
>
>/peter
>
>------------
>Peter Neubauer
>Software Manager
>ScanCoin AB
>Jägershillgatan 26
>213 75 Malmö /Sweden
>
>Phone:  +46 40 6000 687
>mail: pnb@scancoin.se 
>
>  
>
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-- 

Stephen J. McConnell
mailto:mcconnell@apache.org

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