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From "Andrei Ivanov" <my...@surfeu.fi>
Subject Doesn't work Re: Using Service / Component Selector in Phoenix
Date Tue, 11 Jun 2002 21:29:56 GMT
Hm, after closer look I see that this solution doesn't work.
It just shows how to use other role names (that class name) but it doesn't
tell how to select implementations :-(

Andrei

----- Original Message -----
From: "Stephen McConnell" <mcconnell@osm.net>
To: "Avalon-Phoenix Developers List" <avalon-phoenix-dev@jakarta.apache.org>
Sent: Tuesday, June 11, 2002 4:03 PM
Subject: Re: Using Service / Component Selector in Phoenix


>
>
> The document
> http://jakarta.apache.org/avalon/phoenix/guide-example-configuration.html
> contains a description of how to handle this inside Phoinix.
>
> Cheers, Steve.
>
>
> Andrei Ivanov wrote:
>
> >Hi,
> >I came across with simple problem (I think it is simple for experienced
> >Avalon developers) with my Phoenix-based application.
> >
> >The problem is as follows:
> >I have phoenix service which contract is defined in interface
> >
> >A. ServiceInterface
> >
> >I have two different block which offer service A (in other words
different
> >implementation for the same service):
> >
> >Blocks
> >B. offers A
> >C. offers A
> >
> >B and C should be configured and initialized differently as well as they
> >will depend on different services.
> >
> >I would like to be able to specify which block will be used (B or C) to
> >provide service A changing only configuration (config.xml) file.
> >Can anyone give me example how to achieve that and what is the standard
> >practice for Phoenix-based application for this?
> >
> >Regards,
> >Andrei
> >
> >
> >
> >----- Original Message -----
> >From: "Peter Royal" <proyal@apache.org>
> >To: "Avalon-Phoenix Developers List"
<avalon-phoenix-dev@jakarta.apache.org>
> >Sent: Monday, June 10, 2002 5:44 PM
> >Subject: Re: Constraints on dependencies
> >
> >
> >
> >
> >>On Thursday 06 June 2002 07:43 pm, Peter Donald wrote:
> >>
> >>
> >>>1. Are constraints container specific or not?
> >>>2. Is there a subset of constraints that are container agnostic?
> >>>3. How do we represent constraints in the system? An opaque string? A
> >>>Configuration tree? An XPath expression?
> >>>4. Do the providers or the Kernel validate the constraints?
> >>>5. Do the providers get informed that they must conform to certain
> >>>constraints?
> >>>6. Does validation occur at initialization time or assembly time?
> >>>
> >>>My answers would be;
> >>>
> >>>
> >>1. Sometimes. I haven't seen any container-specific examples yet though
;)
> >>2. Yes. Mainly anything that involves lookup( ROLE ), ie. component
> >>
> >>
> >assembly
> >
> >
> >>3. XPath or other evaluated expression :)
> >>4. Kernel
> >>5. No, but there may be cases where they need to be queried by the
kernel
> >>
> >>
> >for
> >
> >
> >>constraint resolution (like the ORB example. the kernel will most likely
> >>
> >>
> >be
> >
> >
> >>unaware that its ORB component hosts others)
> >>6. Both. As much as possible should be done at assembly, but I'm sure
some
> >>must be defered to init time.
> >>
> >>
> >>
> >>>The problem is basically that in some cases it is going to be
> >>>
> >>>
> >practically
> >
> >
> >>>impossible for kernel to validate the constraint unless the provider
> >>>conforms to very specific contracts or is self validating.
> >>>
> >>>
> >>I agree. I'd opt more for the "specific contracts" option, which could
be
> >>
> >>
> >as
> >
> >
> >>easy as exposing MetaInfo classes.
> >>-pete
> >>
> >>--
> >>peter royal -> proyal@apache.org
> >>
> >>--
> >>To unsubscribe, e-mail:
> >>
> >>
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> >
> >
> >>For additional commands, e-mail:
> >>
> >>
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> >
> >
> >
> >
> >--
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> >For additional commands, e-mail:
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> >
> >
> >
>
> --
>
> Stephen J. McConnell
>
> OSM SARL
> digital products for a global economy
> mailto:mcconnell@osm.net
> http://www.osm.net
>
>
>
>
> --
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