Re: [wsrf] WS-RAP; section 2.3 - WS-Resource definition

[Susan Malaika <malaika@us.ibm.com>]

I have some questions:

1. Do resource lifetime and resource properties characterize the lifetime and properties of the logical entity?
2. Is the logical entity in one-to-one correspondence with the WS-Resource?
3. Is the WS-Resource the same as the logical entity?

Susan Malaika

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To: wsrf@lists.oasis-open.org
cc:
Subject: Re: [wsrf] WS-RAP; section 2.3 - WS-Resource definition




In order to minimize impacts on the specifications while accommodating the use cases I have raised, I would suggest inserting the word "logical" into the definition in section 2.1 so that it will read:

      A resource is a logical entity ...

This definition:

1. Enables the client and protocol to view a WS-Resource as referencing a single resource.
2. Allows a web service architect to map the logical entity onto as many physical entities as is appropriate. It also concisely captures the requirement that any such mapping cover all issues of providing a single logical view onto the underlying set of physical entities.

As to the correlated issue of resource identifiers that arose, I think it is the responsibility of each embodiment to call out how multiple parts of a compound identifier can be represented. 

Rich

Rich Thompson/Watson/IBM

10/06/2004 08:41 AM

To	wsrf@lists.oasis-open.org
cc
Subject	Re: [wsrf] WS-RAP; section 2.3 - WS-Resource definitionLink

Why would a WS-Resource be restricted to using a single identifier? It is natural in many systems to use a multi-key lookup. A good example I am quite familiar with is that my employee number is now shared by three IBM employees around the globe. The proper lookup to access my stateful information requires a multi-key lookup using my employee number and country identifier. 

I would agree that from the client's point of view there is a single logical resource associated with the WS-Resource. The points I am raising relate to whether the specification language goes further than that and requires that there only be a single actual resource associated with the WS-Resource. The current language does require that and I question why this limitation on the WS-Resource is valuable to either the protocol or the WS-Resource client. 

Rich

Ian Robinson <ian_robinson@uk.ibm.com>

10/06/2004 07:51 AM

To	Rich Thompson/Watson/IBM@IBMUS
cc	wsrf@lists.oasis-open.org
Subject	Re: [wsrf] WS-RAP; section 2.3 - WS-Resource definition

Rich,
There is a single resource identifier in any message to the WS-Resource.
How the remote portlet WS-Reource treats that resource identifier is up to
the WS-Resource. Looking at this from the perspective of resource
properties, if the identifier represents an aggregation of entities that
that remote portlet models as resources, then the resource properties
document associated with the WS-Resource must be a view over the properties
of all such entites - i.e they are a single logical resource. There is no
notion that a WS-Resource may have a set of resource property documents.

Regards,
Ian



                                                                          
            Rich Thompson                                                 
            <richt2@us.ibm.co                                             
            m>                                                         To 
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            05/10/2004 23:18                                           cc 
                                                                          
                                                                  Subject 
                                      Re: [wsrf] WS-RAP; section 2.3 -    
                                      WS-Resource definition              
                                                                          
                                                                          
                                                                          
                                                                          
                                                                          
                                                                          





One of the things I appreciate about the definition set in WS-RAP is that
it clearly separates a resource from a WS-Resource. I agree that the
portlet is a WS-Resource, but it is encapsulating multiple resources rather
than multiple WS-Resources. The essence of my question is whether the web
service endpoint is allowed to operate on multiple resources or whether
there is a strict one-to-one mapping of resource to WS-Resource. Clearly
the portlet could invent a wrapper resource that merely encapsulates the
underlying resources, but why should that be required?

On the ramifications of allowing this broadening, I think we all agree that
this can be done without the client being aware of it. The client is
interacting with a WS-Resource and it has no idea of the meaning of the
various parts (could include a separate identifier for each resource) of
the endpoint that it has been given, only that it has to follow the
contract of the binding to the WS-Resource that is in use.

Rich

                                                                          
Tom                                                                       
Maguire/Hawthorne/IBM@IBMUS                                               
                                                                          
                                                                       To 
10/05/2004 02:56 PM                       Rich Thompson/Watson/IBM@IBMUS  
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                                                                  Subject 
                                          Re: [wsrf] WS-RAP; section 2.3  
                                          - WS-Resource definition        
                                                                          
                                                                          
                                                                          
                                                                          
                                                                          
                                                                          
                                                                          









So I guess I'm struggling with this a bit.  From the client's perspective
you have a single
WS-Resource.  That WS-Resource has an identifier.  As you mentioned the
client would
not need to know or care that multiple resources are involved.  In WS
Remote Portlet it
sounds as if there is a need to do a composition of multiple (different
types of )
WS-Resources and the "portlet" endpoint is responsible for dispatch to the
underlying
"encapsulated" WS-Resources.  In this model I think the WS-Resource is the
remote portlet.
That remote portlet has its own identifier.  That identifier is used as a
resource disambiguator
to the "collection" of related WS-Resources not to the individual
WS-Resources of the collection.

So I agree that clients should not care but I would also argue then that
from the clients
perspective there is just one WS-Resource and that the definition of a
WS-Resource
is correct from that perspective.

Tom

Problems cannot be solved at the same level of awareness that created
them.  —Albert Einstein
T o m   M a g u i r e

STSM, On Demand Architecture
Poughkeepsie, NY  12601

Rich Thompson/Watson/IBM@IBMUS wrote on 10/05/2004 01:43:27 PM:

>
> Not quite our situation. Certain operations will need to access more
> than one resource during the processing of a single message. How the
> set of resources is constructed and referenced by the endpoint would
> be a matter between the factory and the resource disambigurator. I
> would hope the client would not need to know or care that multiple
> resources are involved and am raising the case seeking that both the
> language and semantics permit such a pairing of a web service and a
> set of resources within a single endpoint without requiring
> knowledgeable clients.
>
> Rich
>

>
> Steve Graham/Raleigh/IBM
> 10/05/2004 09:51 AM
>
> To
>
> Rich Thompson/Watson/IBM@IBMUS
>
> cc
>
> wsrf@lists.oasis-open.org
>
> Subject
>
> Re: [wsrf] WS-RAP; section 2.3 - WS-Resource definitionLink
>
>
>
> Rich:
> To clarify, your situation is such that a Web service deployed at
> some URL is the access point for a collection (potentially many)
resources?
>
> Given my assumption is true, I don't see why you have come to the
> conclusion that the definition of WS-Resource precludes it.  The
> examples in the WSA embodiments (sections 3.1 and 3.2) suggest this
> pattern where a single web service is front ending 2 resources.
> Note that it is the pair (web service + resource) that is the WS-
> Resource. So in the examples in the WSA embodiments contain 2
WS-Resources.
>
> Does this help?
>
> ++++++++
> Steve Graham
> (919)254-0615 (T/L 444)
> STSM, On Demand Architecture
> Member, IBM Academy of Technology
> <Soli Deo Gloria/>
> ++++++++
>
>
> Rich Thompson/Watson/IBM@IBMUS wrote on 10/05/2004 08:53:02 AM:
>
> > While I haven't finished working through exactly how the WSRP
> protocol could best
> > leverage WSRF, I (and others on the WSRP TC) are leaning towards
> the at least some
> > of the web service endpoints containing references to a set of
> resources rather
> > than just one. The proposed definition ("A WS-Resource is a Web
> service through
> > which a resource can be accessed.") excludes such use cases. Any reason
the
> > definition can not be broadened to "A WS-Resource is a Web service
> through which a
> > set of one or more resources can be accessed." This would carry
> into many other
> > places in the text where the resource is referred to in the singular.
> > Rich Thompson
> > OASIS WSRP TC Chair