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Re: Typical SOA ... SOA Patterns

From: Francis McCabe <frankmccabe@mac.com>
Date: Sat, 31 Jan 2004 18:19:55 -0800
Message-Id: <2000E628-545D-11D8-81A1-000A95DC494A@mac.com>
Cc: www-ws-arch@w3.org
To: Paul Denning <pauld@mitre.org>

Paul:
  If you really had such substantive issues, it is way too late to bring  
them up. In fact, you could have done so many weeks ago.

  One the matter of intermediaries, it is not fair to say that  
"intermediaries are an unresolved issue" in the WSA. They are not  
issues, and nor are they especially unresolved.

One comment: although it is slightly stretching the use case, I see no  
special reason technically why certain kinds of broker patterns would  
not fit into the intermediary model. I realize that others may not  
agree with me on this.

Certainly, in our work, we would use v. similar patterns that  
definitely would fit in with the intermediary/broker kind of pattern.

Frank

P.S. I guess that its kind of ironic that we get more traffic on this  
list *after* the WG is closed than for many months!


On Jan 30, 2004, at 2:36 PM, Paul Denning wrote:

>
> (See my reply to David Booth, which says this should not be added as a  
> separate issue, but the agreed upon unresolved issues could say  
> something about SOA.  Specifically, the issue about correlation, and  
> the issue about intermediaries.)
>
> That's the point.
> We're talking about the "unresolved issues".
> I guess you're not grasping what I think is the unresolved issue, and  
> you cannot agree that it is unresolved.
> OK.
> Perhaps "relationships between and patterns for" causes confusion.
> So maybe simply "More work needed on SOA" would work.
>
> Perhaps that is obvious and will get addressed in due time by W3C or  
> elsewhere.
>
> I was pulled away from the F2F this week so I could not work this  
> unresolved issue in earlier.
>
> By the way, I was pulled away because I am working on an effort which  
> has as one of its goals "to establish the value of a SOA approach for  
> xxx".
>
> The term "broker" gets used quite a bit in my environment lately, and  
> I have been trying to define how a "broker" fits into SOA, and  
> hopefully apply concepts from WSA.
>
> Broker was not a term I wanted to introduce to the WSA trout pond.  In  
> discussions with my colleagues, we talk about simple brokers and more  
> complex brokers.  But we need to relate these "brokers" to the "SOA  
> approach".
>
> In WSA, we have intermediaries as an unresolved issue.  Intermediaries  
> could be SOAP intermediaries, or perhaps things we could call brokers.  
>  Perhaps there are different types of brokers and each can be  
> identified by a role.  A broker might be a web service like any other,  
> with its own WSDL and SOAP endpoint.  A broker that sits between a  
> requester and some other service, in a high level view, might just  
> look like two web services.  The broker may act in one role, and the  
> actual service may be another role.  The broker may act as a requester  
> for the other service.  A specific set of roles might be used in  
> defining a particular SOA Pattern.
>
> We (WSAWG) eliminated the triangle diagram from the WSA, which is OK.
> We do not talk about the triangle diagram in the section on SOA, which  
> is OK.
>
> I guess I'm hoping for more clarity on SOA, in a standard would be  
> nice.  WSA says some things about discovery, registries, indexes, and  
> discovery federation, which relate to the "simple broker" stuff that I  
> deal with in my day job.  I feel like I need more when it comes to  
> relating complex brokers to SOA.   Given more time with WSAWG, or  
> perhaps in another WG or effort, I would probably explore "SOA  
> Patterns".  If the minimal essential SOA is Interface Description and  
> Messages, then adding things like brokers would be a SOA Pattern; a  
> way of using SOA.
>
> Maybe WS-CDL (choreography) will get into things that I am calling SOA  
> Patterns.  The problem I see is that WS-CDL would describe  
> interactions between busineses, but brokers might be used within one  
> of the businesses and would not have a place in WS-CDL.  WS-CDL might  
> get converted to BPEL for one side of the interaction, which would  
> imply a BPEL engine (or broker).  So neither WS-CDL nor BPEL may give  
> me a view of the SOA Pattern used inside that organization.  I do not  
> know enough of the details of either WS-CDL nor BPEL to say for sure  
> whether or not they can express SOA Patterns.
>
> WSA section 3.4.3 says "Note that each registry or index may provide a  
> web service for discovery, so it may be appropriate to use a  
> choreography or orchestration description language to describe the  
> exchanges among these services needed for federation."  To the extent  
> brokers are involved with discovery and provide a web service  
> interface, I may be able to define the exchanges in BPEL.  Brokers  
> that deal with things like content-based routing and message  
> transformation may also have roles worth defining so we can use them  
> in SOA Patterns.  Some brokers claim to do load balancing and failover  
> (LB/FO).  If I have SOA, do I get LB/FO?  If minimum essential SOA  
> does not provide it, what SOA Patterns do I need to get LB/FO?  If  
> there are different ways of doing these things, then when a need  
> arises to combine services but not lose LB/FO, it would be nice for  
> architects to have a way to articulate what they have and what they  
> need.
>
> I'll start a thread over in ws-chor to see if/how they are addressing  
> any of this.
>
> Paul
>
> At 11:55 AM 2004-01-30, Cutler, Roger (RogerCutler) wrote:
>> In my humble opinion it is too late.  Even though I would probably
>> support such a statement (if I understood it), I think that it is VERY
>> clearly substantive and beyond the scope of mechanical preparation for
>> publication.  I think that it would be a VERY bad precedent to sneak a
>> substantive change in after the WG has disbanded.  In addition, I  
>> think
>> that the fact that as a former member of the former working group I
>> honestly do not understand what the statement means or the  
>> ramifications
>> of it indicates that discussion would have been required had it been
>> proposed during the working session of the group.
>>
>> Sorry.
>>
>> -----Original Message-----
>> From: www-ws-arch-request@w3.org [mailto:www-ws-arch-request@w3.org]  
>> On
>> Behalf Of Paul Denning
>> Sent: Friday, January 30, 2004 10:40 AM
>> To: www-ws-arch@w3.org
>> Subject: RE: Typical SOA ... SOA Patterns
>>
>>
>>
>> At 10:20 AM 2004-01-30, Champion, Mike wrote:
>> >I completely agree.  The problem is that it is January 30th; the WG
>> >charter ends tomorrow, and we are simply out of time to make *any*
>> >substantive changes to the Note.  (Typos, broken links, etc. can be
>> >reported and fixed until Wednesday, I believe).
>>
>> I guess it is up to the editors to add verbiage (perhaps, or do
>> something
>> with @@) in section 4.3 [1], which now reads
>>
>> 4.3 Significant Unresolved Issues
>>
>> @@What is the difference between an MEP and a Choreography?
>>
>> @@What should be the representation returned by an HTTP "GET" on a Web
>> service URI?
>>
>> @@Should URIs be used to identify Web services components, rather than
>> QNames?
>>
>> @@The relationship between privacy and Web services technology needs
>> clarification.
>>
>> @@SOAP 1.2 and this architecture introduce the concept of
>> "intermediaries",
>> but this concept is not represented in WSDL 2.0.
>>
>> @@[wordsmith:] What happens if two WSDL documents define the same
>> service?
>>
>> @@The relationship between conversations, correlations and  
>> transactions
>> and
>> choreography is unclear and needs more work.
>>
>> @@There is a need for consistent tracking mechanisms in Web services.
>>
>> ------
>> I am proposing
>>
>> @@Further work on the relationships between and patterns for using Web
>> services and SOA.
>>
>> (Would be nice to add it if we can, but I understand if it is too  
>> late.)
>>
>> [1]
>> http://dev.w3.org/cvsweb/~checkout~/2002/ws/arch/wsa/wd-wsa-arch- 
>> review2
>> .html#id5212661
>>
>> Paul
>
>
Received on Saturday, 31 January 2004 21:20:30 GMT

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