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Subject: Re: [wsrf] WS-RAP; section 2.3 - WS-Resource definition
- From: Rich Thompson <richt2@us.ibm.com>
- To: wsrf@lists.oasis-open.org
- Date: Thu, 7 Oct 2004 08:22:07 -0700
My view would be:
- Both resource lifetime and properties
are at the logical entity level. This is one of the issues anyone mapping
between the logical entity and multiple physical entities must manage.
- A WS-Resource only refers to
a single logical entity, though multiple WS-Resources may refer to the
same logical entity. This keeps the protocol and client view significantly
simpler than any form of bleeding the mapping through could do (i.e. keeps
the complexity with the party that introduced it and knows how to manage
it).
- The WS-Resource is not the same
as the logical entity. The logical entity encapsulates stateful information
that the web service needs when processing messages. The WSRF defined messages
tend to be targeted at this stateful information, but processing of WS-Resource
specific messages might use the stateful information rather than being
targeted at it.
Rich
Susan Malaika/Santa Teresa/IBM@IBMUS
10/07/2004 10:53 AM
|
To
| Rich Thompson/Watson/IBM@IBMUS
|
cc
| wsrf@lists.oasis-open.org
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Subject
| Re: [wsrf] WS-RAP; section
2.3 - WS-Resource definition |
|
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
.....................................................................................................................................................................................................................................................
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
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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
wsrf@lists.oasis-open.org
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
cc
wsrf@lists.oasis-open.org
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
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