Please allow to emphasize
the „single resource, multiple identifier“ aspect: An instance of
a BPEL process is a resource in many scenarios. And a single process instance
may have many different identifiers in BPEL (so-called “correlation IDs”).
Thus, a BPEL process instance is a single resource with multiple identifiers.
Gruss, Regards,
Frank Leymann
-----Ursprüngliche Nachricht-----
Von: Rich Thompson
[mailto:richt2@us.ibm.com]
Gesendet: Thursday, October 07,
2004 2:25 PM
An: wsrf@lists.oasis-open.org
Betreff: 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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Re: [wsrf] WS-RAP; section 2.3 - WS-Resource
definitionLink
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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
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Re: [wsrf] WS-RAP; section 2.3 - WS-Resource
definition
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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