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Subject: Re: [ws-caf] Mt Everest and WS-CF
Jan, may I suggest also that you look at: http://www.w3.org/Submission/2004/SUBM-ws-messagedelivery-20040426/ Jan Alexander wrote: >So if I understand this correctly, your original comment was not about >WS-Addressing at all, since WS-Addressing does not place context related >information within an address. The other question is, whether the concept of >the EndpointReference (encapsulation of the address and other endpoint >instance related information), as defined by WS-Addressing, is appropriate for >Web Services. Is it right? > >From my experience with Web Services, having only a transport address of the >endpoint is not always enough to be able to communicate with the service - I'm >not talking about message formats here, you have to know them too of course . >It is helpful to have a mechanism to embed additional properties (like >policies) to the particular web service instance reference, that, as you said, >shouldn't be placed inside the original Web Service endpoint address. Such a >endpoint reference can then be placed into a WSDL describing that particular >web service instance instead of the transport address of the endpoint. >Unfortunately this cannot be easily accomplished using WSDL 1.1. This is not >about WS-RF, which is going a lot of further and is defining concept of >resource and association between the resource and the service, which executes >in the resource context. I agree, that this is rather a questionable thing to >do in Web Services environment in general. > >Jan > > > _____ > >From: Mark Little [mailto:mark.little@arjuna.com] >Sent: Friday, May 28, 2004 11:53 AM >To: Jan Alexander; 'Greg Pavlik'; 'Furniss, Peter' >Cc: 'Green, Alastair J.'; 'ws-caf' >Subject: Re: [ws-caf] Mt Everest and WS-CF > > >Jan, I hope you didn't think I was suggesting that WS-Addressing does place >context into the address, but rather commenting on 'WS-Addressing is >particularly interesting because it is essentially "opaque context"' As I >said, context shouldn't be within an address. > >However, it's a different argument as to whether the use of >ReferenceProperties to create the equivalent of an IOR >(ReferenceProperties==Object Key) is a good thing. If you read the recent >paper on WSJ comparing WS-Context with WS-RF I think you'll see the argument >against in a much stronger way than I have time to write in this email. > >Mark. > >----- Original Message ----- >From: Jan Alexander <mailto:alex@systinet.com> >To: 'Mark Little' <mailto:mark.little@arjuna.com> ; 'Greg ><mailto:greg.pavlik@oracle.com> Pavlik' ; 'Furniss, Peter' ><mailto:Peter.Furniss@choreology.com> >Cc: 'Green, Alastair J.' <mailto:Alastair.Green@choreology.com> ; 'ws-caf' ><mailto:ws-caf@lists.oasis-open.org> >Sent: Friday, May 28, 2004 10:42 AM >Subject: RE: [ws-caf] Mt Everest and WS-CF > >WS-Addressing does not place context into the address. What it does, it uses >set of SOAP headers to identify execution context for the particular >"Endpoint" by introducing EndpointReference abstraction. The EndpointReference >itself additionally contains logical address of the endpoint and a set of >policies, which are relevant to the use of that EndpointReference. > >It is important to distinguish between a service address and a service >instance identifier. The first is similar to for instance IP addresses and >port number, the second to CORBA IOR. I don't see anything against "SOA >principles" in the EndpointReference concept as it is not just a service >address. I agree that it would be useful to use WS-Context for mapping >EndpointReferenceProperties into SOAP headers as they identify the execution >context of the endpoint. > >Jan > > > _____ > >From: Mark Little [mailto:mark.little@arjuna.com] >Sent: Friday, May 28, 2004 11:25 AM >To: Greg Pavlik; Furniss, Peter >Cc: Green, Alastair J.; ws-caf >Subject: Re: [ws-caf] Mt Everest and WS-CF > > >+1. > >I'd also like to suggest that context embedded in an address isn't really the >right way to go. Despite the fact that we (Jim, Savas, myself and others) have >suggested that ReferenceProperties *could* use WS-Context, that doesn't >necessarily mean that it's the best way of tackling the problem. Suggesting >that context within an address is the right model is ignoring SOA principles. > >Mark. > >----- Original Message ----- >From: Greg Pavlik <mailto:greg.pavlik@oracle.com> >To: Furniss, Peter <mailto:Peter.Furniss@choreology.com> >Cc: Green, Alastair J. <mailto:Alastair.Green@choreology.com> ; Mark ><mailto:mark.little@arjuna.com> Little ; ws-caf ><mailto:ws-caf@lists.oasis-open.org> >Sent: Thursday, May 27, 2004 3:56 PM >Subject: Re: [ws-caf] Mt Everest and WS-CF > > > >Furniss, Peter wrote: > > >Greg, > > > ><snip the earlier part of the alastair .. thread> > > > > > >A further comment on the IBM/MS product specs: there are in > >fact three > >contextualization mechanisms: one in WS-Coordination, one in > >WS-ReliableMessaging, and one in WS-Addressing. Putting aside > >WS-Addressing for a moment since it introduces a new model to the web > >services environment that I don't want to argue about here, let me > >observe that there is no fundamental distinction between the > >lifecycle > >control interface in WS-Coordination and WS-ReliableMessaging. Why > >shouldn't these be based on a common model? Wouldn't that in fact be > >simpler and less error prone? From there, it seems a small step to > >imagine the reliability and coordination/transaction contexts > >having a > >common root. I submit that this is in fact a flaw, not a strength, of > >the specification set; they they are unnecessarily complex due to the > >failure to deal with common constructs, idioms and patterns as, well, > >things-in-common. > > > > > > > >Well the WS-Coordination and WS-RM both have equivalent of "begin". > >WS-RM doesn't always use it, > >and when it is used, it is asked of the eventual receiver. The > >termination sequences are different, since WS-RM is just stopping, and > >WS-Coordination will have delegated to a transaction protocol. > > > >As contextualization, it is true that a message carrying the relevant > >headers is "in the context" of those headers, and subject to their > >implications. But the same is true of more or less any header - that's > >what they're for. WS-Addressing is particularly interesting because it > >is essentially "opaque context" - the reference properties don't need to > >contain any kind of identifier in the ws-context sense at all (it might > >tell the receiver which database to look in, but since only the receiver > >knows what they meant, that's fine - it's just a piece of syntactic > >partitioning of the address) > >Is it fine? What if it happens to conflict with another header since there are >no restrictions? I'd like to suggest that WS-Addressing would benefit from a >container and that this is generally a problem for contextualization based >solely on headers. > > > >. The other two would have an identifier but > >that's the only thing they share, I think. > > > >Peter > > > > > >
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