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Subject: Re: [soa-rm-ra] Strawman of outstanding issues

The text is using a third party Registry-Repository as one example of mediated awareness - there can be many ways to provide awareness. Mediator is a behavioral pattern and in this example the behavior is mediated awareness.  As chair Ken mediates SC meetings, MatchMaker.com mediates people meeting each other, etc.
The article in the link seems to use facade and mediator synonymously.  Facade is structural.  I have created many a facade for business logic and underlying data access.  Facade tells me about an architectural structure. It may be that my facade is just a wrapper on entity beans to access DB tables in which case I would not denote it as a mediator in the architectural description. 

--- On Wed, 12/8/10, mpoulin@usa.com <mpoulin@usa.com> wrote:

From: mpoulin@usa.com <mpoulin@usa.com>
Subject: Re: [soa-rm-ra] Strawman of outstanding issues
To: danny_thornton2@yahoo.com, boris.lublinsky@navteq.com, soa-rm-ra@lists.oasis-open.org, peter@peterfbrown.com
Date: Wednesday, December 8, 2010, 1:15 PM


A mediator MAY be known to service consumers and services/providers. Yes, you put this Mediator into the Service Description and, respectively, into the Services Contract, no problems. However, awareness and registry-repository have NOTHING to do with each other IMO while I have the same understanding of registry and repository as you describe.

I believe that the statement "Mediated awareness promotes loose coupling by keeping the consumers and services from explicitly referring to each other and the descriptions" and "Mediation lets interaction vary independently" contradicts 90% of current RAF. In SOA, not in Web Services, consumer and service/provider MUST know each other ( as in Business ) to agree on the service use, to sign the Service Contract.

Interaction between consumer and service MAY NOT be independent from them, it is not service orientation. Service registry/repository STORES information and nothing more. Consumers can use them or ignore them, it is up to them, we have no controls over them to enforce usage of registry/repository. Saying that re-direction via registry/repository is a good thing may be possible in only one case: participants of the consumer-service interaction are aware about such indirection. This is why I am saying that ESB pattern has been incorrectly represented in the form of ESB products. ESB may not hide interacting actors, it has only simplify this interaction.

- Michael

-----Original Message-----
From: Danny Thornton <danny_thornton2@yahoo.com>
To: BorisLublinsky <boris.lublinsky@navteq.com>; soa-rm-ra@lists.oasis-open.org <soa-rm-ra@lists.oasis-open.org>; Peter F Brown at work <peter@peterfbrown.com>
Sent: Wed, Dec 8, 2010 8:27 pm
Subject: RE: [soa-rm-ra] Strawman of outstanding issues

Within the context of the SOA RAF, Section 4.2:
Service consumers and service providers may have direct awareness or mediated awareness where mediated awareness is achieved through some third party.
A common mechanism for mediated awareness is a registry-repository. The registry stores links or pointers to service description artifacts. The repository in this example is the storage location for the service description artifacts.
Mediated awareness promotes loose coupling by keeping the consumers and services from explicitly referring to each other and the descriptions. Mediation lets interaction vary independently.

--- On Wed, 12/8/10, Peter F Brown at work <peter@peterfbrown.com> wrote:

From: Peter F Brown at work <peter@peterfbrown.com>
Subject: RE: [soa-rm-ra] Strawman of outstanding issues
To: "Lublinsky, Boris" <boris.lublinsky@navteq.com>, "soa-rm-ra@lists.oasis-open.org" <soa-rm-ra@lists.oasis-open.org>
Date: Wednesday, December 8, 2010, 12:09 PM

So registry is also a service but not part of 'the' service that is playing the role of provider? Is it a service performing a different role? It's capability offering being rather specialized (eg service discovery)? Going back to the model, is it simply another (of potentially many) role played by a participant in the ecosystem?

Peter F Brown
Independent Consultant

Sent from my Windows Phone - Apologies for typos, levity and brevity - it's hard to type on a moving planet

From: Lublinsky, Boris
Sent: Wednesday, 08 December, 2010 6:48
To: peter@peterfbrown.com; soa-rm-ra@lists.oasis-open.org
Subject: RE: [soa-rm-ra] Strawman of outstanding issues

> Peter,
> This is a good deck.
> A couple of comments:
> Mediator
> -? is a registry a good example? Do we have better ones? Is it more than mediator?
> I do not consider a registry to be a mediator. A registry is a specialized entity in his own right with its own set of goals.
> Typically a mediator is an entity that is invoking service on behalf as a consumer and is seen by consumer as a service (compare to proxy in a distributed system). The difference between mediator and a simple proxy is significant - mediator is more like an interpreter in a conversation between people speaking different languages. Typical mediators do the following - transport transformation (for example MOM to HTTP), semantic alignment (data transformation), dynamic routing, often leveraging registry (version-based routing, etc)
> I am not sure how Skill is relevant for SOA
> I have a real issue with introducing resources into SOA. The problem is Resources are orthogonal to services - it is a completely different model of the world - see REST vs SOA. A service implementation internally does depend on resources, but this is opaque to the service consumer.
> The issue here is that SOA is based on the functional decomposition, where functions can cross resource boundaries, where Resource decomposition is based on identifying resources, regardless of services they provide. A system can be build either way, but those will be 2 different systems. The relationship is similar to entity beans (resource) vs session beans (services).
> Semantics is a really hard one. The issue is that in SOA semantics is defined by service provider. It is NOT specific to a consumer/provider pair. A service consumer can have his own semantics, but he typically has to use a mediator for resolving semantic differences
> From: Peter F Brown [mailto:peter@peterfbrown.com]
> Sent: Tuesday, December 07, 2010 8:09 PM
> To: soa-rm-ra@lists.oasis-open.org
> Subject: [soa-rm-ra] Strawman of outstanding issues
> Hi:
> We have worked through the entirety of outstanding issues, questions and concerns for section 3 (along the way, examining also sections 1 & 2). We have, inevitably many, many, edits to propose!
> However, and as promised on last week's call, we now present a "Strawman", in the form of the attached slide deck which we think touches on all the main issues and provides a narrative for addressing them.
> We stress this is not an editing exercise but an attempt to gain consensus on the main issues, definitions and relationships between terms before the proceeding with presenting detailed dispositions of textual changes, in line with said consensus.
> As previously announced, I will not be able to join the call tomorrow as I'll be some 30,000 feet over Kansas at the time of the call. Chris Bashioum will lead off as your Maître d'
> Regards,
> Peter
> Peter F Brown
> Independent Consultant
> [cid:image001.png@01CB96AC.EA7AD190]
> Transforming our Relationships with Information Technologies
> www.peterfbrown.com
> @pensivepeter<http://twitter.com/#!/@pensivepeter>;
> P.O. Box 49719, Los Angeles, CA 90049, USA
> Tel: +1.310.694.2278
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