- From: Williams, Stuart <skw@hplb.hpl.hp.com>
- Date: Mon, 22 Oct 2001 18:30:54 +0100
- To: "'Kumeda'" <kumeda@atc.yamatake.co.jp>
- Cc: xml-dist-app@w3.org
Kumeda, Firstly, I very much like the way that you have framed the issue, the diagram and the five types contract. Your framing also, clearly identifies that it is Contract 4 that is at issue. > Contract4 is very important for an entire system to operate as desired, but > shall be defined by the transport layers. In other words, SOAP needs to use > whatever services defined by the lower transport layers. If some functions are > not provided by a certain transport layer, such as request-response bindings, > they need be defined within the SOAP specifications. One of the reasons that Contract 4 is important is because it effectively defines the semantics of the channel over which SOAP operates. Once you can 'articulate' the nature of a 'Contract 4' then you can work (within SOAP) on the protocol mechanisms (Contract 3) required to support 'Contract 2'. The TBTF is trying to address the issue of Contract 4. We could take an approach that 'normalised' 'Contract 4' ie. regardless of what lies below, all 'Contract 4's are the same... this is the approach that IP (and indeed TCP) uses... and the bindings of IP to some underlying protocols (eg. X.25) do introduce mechanism in order to support the semantics of IP's 'contract 4'. Alternatively... we could take a view that every different underlying protocol and binding provides different services into the SOAP layer, in which case, different protocols/protocol+binding have different 'contract 4's. If we then go on to leave that competely open-ended... then I think there is very little, if anything, we can say normatively about the mechanisms of 'Contract 3' (which I think we are agreed are in-scope for the SOAP spec.) because can say nothing about 'Contract 4'. I think that the TBTF is trying to tread a middle path where there is not a single normalised 'Contract 4' but where there is a repetoire of 'component descriptions' that can be matched to the capabilities of particular underlying protocols (and their bindings). I'd like to ask you, if you have no knowledge of 'contract 4' how do you develop the mechanism of 'contract 3' to support 'contract 2'? Once again, thanks for the framing, I think it helps to get us to the heart of the issue. Best regards Stuart Williams > -----Original Message----- > From: Kumeda [mailto:kumeda@atc.yamatake.co.jp] > Sent: 22 October 2001 11:05 > To: xml-dist-app@w3.org > Subject: Re: SOAP Binding Framework Concerns > > > Please allow me to post to this mailing list for the first time. My name is > Yasuo Kumeda, a communications engineer working for Yamatake Corporation in > Japan. > > I am in agreement with Marwan's post on the 19, in which he stated concerns > against the binding framework. It seems to me that the TBTF may try to define > something outside the scope of transport bindings. > > To transfer SOAP messages from one application to another, there are couple of > "contracts" associated with the transactions as shown in the figure below. I > believe the SOAP biding framework should only define contract2 and contract3, as > explained below: > > +-------------------+ +-------------------+ > | Application |<--contract1-->| Application | > +-------------------+ +-------------------+ > ^ ^ > | contract2 contract2 | > v v > +-------------------+ +-------------------+ > | SOAP |<-- contract3-->| SOAP | > +-------------------+ +-------------------+ > ^ ^ > | contract4 contract4 | > v v > +-------------------+ +-------------------+ > | Transport |<-- contract5-->| Transport | > +-------------------+ +-------------------+ > > > Contract1 is agreements between applications, i.e., SOAP users. > Contract2 is agreements between a SOAP user and the SOAP communication layer. > Contract3 is agreements between two or more SOAP communication layers. > Contract4 is agreements between the SOAP communication layer and a transport > layer. > Contract5 is agreements between two or more transport layers. > > According to the communication layering model defined by the OSI, contract1, > contract3, and contract5 are "PROTOCOLS" between peer communication layers, > whereas contract2 and contract4 are "SERVICES" between adjacent communication > layers. > > Also according to the layering model, the protocols are defined by the peer > communication layers, and the services are defined by a lower layer for the > corresponding upper layer to use them. > > With these definitions, it is clear that contract1 and contract5 are outside the > scope of the TF, and contract3 shall be defined within the SOAP specifications. > > Contract4 is very important for an entire system to operate as desired, but > shall be defined by the transport layers. In other words, SOAP needs to use > whatever services defined by the lower transport layers. If some functions are > not provided by a certain transport layer, such as request-response bindings, > they need be defined within the SOAP specifications. > > With the same token, contract2 shall be defined by the SOAP specifications as > they are services provided by SOAP to applications (SOAP's upper layer). These > services, if properly defined, assure interoperability among different > implementations of SOAP communication layer and SOAP applications. > > To realize scenarios described in [1], this service interface may include > a) Fire_and_Forget_Multi-services > b) Fire_and_Forget_Single-services > c) Request-service > d) Response-service > and so on, > for instance. > > Best regards, > Yasuo Kumeda > > [1] > http://www.w3.org/2000/xp/Group/1/10/18-us/XMLProtocolUsageScenarios > > -- > Kumeda, Yasuo TEL: +81-466-20-2430 > FAX: +81-466-20-2431 > Research and Development Headquarters > Yamatake Corporation > > Fujisawashi Kawana 1-12-2 > Kanagawa, 251-8522 JAPAN >
Received on Monday, 22 October 2001 13:32:53 UTC