Alexi Polenur wrote:
>Thanks Stephen,
>
> It make things clear. I am glad you have chosen to
>leave service package. IMHO names in service package
>better represent the concept. Specifically Composable
>vs. Serviceable. The word Serviceable goes more
>naturally with the "user of something" when
>"something" implies "service".
> I have just one more question what happened with
>equivalent of "Recomposable" in the service package?
>
WHen preparing the service package I did not include a Reservicable
interface because I simply felt that the Recomposable semantics were
underspecified. Discussion on Re-* has recently commenced on the dev list.
>I understand, taht the same method service can
>potentially be used to reassigned a ServiceManager
>for specific Servicable.
>
If a policy concerning reserviceable existed, then yes - it would imply
that the service can be serviced multiple time via the service method.
>However, I thought it was good idea of using the
>special interface to capture design decision of
>allowing or not allowing of such reassignment.
>
>
One of the issues being dealt with is the difference between the
recognition of a policy (such as reservicable) and the mechanisms used
to declare that policy. A Reserviceable interface is an approach (a
marker interface). Another approach is to declare reserviceable policy
at the level of type meta-info. This second approach ensures that
policy is not tied to the object implementation (i.e. it does not need
to appear in the class interface list).
Cheers, Steve.
>Thanks Alexi
>--- Stephen McConnell <[EMAIL PROTECTED]> wrote:
>
>
>>Alexi Polenur wrote:
>>
>>
>>
>>>Hi all,
>>>
>>> I just started discovering Avalon framework, and
>>>
>>>
>>I
>>
>>
>>>have a question described in the title of this
>>>
>>>
>>email.
>>
>>
>>> I think I can understand potential difference
>>>between notion of component and service.
>>> IMHO the Component and Service are very closely
>>>related concepts or rather two different view or
>>>prospective on the same consept.
>>>
>>>
>>>
>>Correct. The service package was introduced as a
>>candidate replacement
>>of the coponent package in order to eliminate
>>artifical implications
>>introduced my the Component interface. In all
>>respects the component
>>package and service package are equivilent with the
>>exception that
>>Component is replaced by java.lang.Object in the
>>service package.
>>
>>
>>
>>>The both refer to the
>>>"reusable", "replaceable", "interchangeable" chunk
>>>
>>>
>>of
>>
>>
>>>software. The difference is that term Component is
>>>used to look at the concept from the "structural"
>>>prospective when term service used to emphasize
>>>"behavior" aspect of the concept. In other words
>>>Service is a Component which exposes set of
>>>
>>>
>>behaviors.
>>
>>
>>Nope - sorry about the confusion here - the service
>>package is
>>functionally the smae as the component package - no
>>semantic
>>differences. The service package is the preferred
>>approach and as work
>>on the container side of things nears completion,
>>wel will probably
>>deprecate the component package and clearly document
>>the reasons,
>>rationale and replacements under the service
>>package.
>>
>>
>>
>>> Even though I would be really interested to hear
>>>your comments on my understanding (right or wrong)
>>>
>>>
>>of
>>
>>
>>>consepts of Service and Component, my real question
>>>
>>>
>>is
>>
>>
>>>more practicle.
>>>
>>> The question is not "What the difference between
>>>Component and Service concepts" but rather "What
>>>
>>>
>>the
>>
>>
>>>reason of having two very similar set of interfaces
>>>one in package
>>>
>>>
>>org.apache.avalon.framework.component
>>
>>
>>>and another in
>>>
>>>
>>org.apache.avalon.framework.service".
>>
>>
>>> Looking at the interfaces and JavaDoc description
>>>
>>>
>>it
>>
>>
>>>seems to me that this two packages are modeling
>>>
>>>
>>very
>>
>>
>>>similar abstractions.
>>>
>>>
>>>
>>>
>>I hope that clears it up for you.
>>
>>Cheers, Steve.
>>
>>
>>
>>>Thanks in advance Alexi
>>>
>>>
>>>
>>>__________________________________________________
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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:[EMAIL PROTECTED]
>>http://www.osm.net
>>
>>
>>
>>
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>>
>
>__________________________________________________
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>
--
Stephen J. McConnell
OSM SARL
digital products for a global economy
mailto:[EMAIL PROTECTED]
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