Fwd: [dais-wg] WSRF Embodiments and DAIS
Ian Foster
foster at mcs.anl.gov
Tue Dec 21 07:20:53 CST 2004
I wanted to ask if I could get some clarification regarding the concerns of
the DAIS-WG relating to the use of WSRF.
When you talk about "non-WSRF middleware", you seem to be concerned in
particular about clients. Now the only requirement beyond WS-I compliance
that is placed on a client of a WSRF service is that it support
WS-Addressing, and WS-Addressing is widely supported by essentially all
major Web services implementations: Axis, BEA, IBM, Microsoft at least.
Thus, this doesn't seem to me to be a major concern.
Are there other concerns that you have?
Ian.
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>>>Subject: [dais-wg] WSRF Embodiments and DAIS
>>>To: dais-wg at gridforum.org, wsrf at lists.oasis-open.org
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>>>From: Susan Malaika <malaika at us.ibm.com>
>>>Date: Fri, 17 Dec 2004 02:21:15 -0800
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>>>The Oasis WSRF group asked the GGF DAIS working group to consider the
>>>WSRF "WSDL 1.1 Binding Element Embodiment". An item was posted to the
>>>DAIS mailing list entitled "DAIS mapping and WSRF embodiments" on 23
>>>November 2004. There has been discussion among the DAIS community on the
>>>use of the WSRF embodiments. Some of the DAIS community involved in the
>>>discussions are the implementers of the first open source version of
>>>DAIS known as OGSA-DAI; they are the first users of DAIS; they are
>>>active in promoting DAIS among data grid communities around the world.
>>>These are some interim conclusions:
>>>
>>>1. Multiple kinds of DAIS Users
>>>It is still not clear if DAIS should mandate WSRF because some of the
>>>participants in the DAIS group rely on non-WSRF middleware. DAIS could
>>>go some way towards satisfying WSRF and non-WSRF users by placing the
>>>resource identifier in the DAIS messages (so a single DAIS message
>>>format could be used by both WSRF and non-WSRF DAIS users).
>>>A note on resource properties:
>>> * Resource properties requests cannot include resource identifiers
>>> in the message body. The resource identifier must be placed in the header.
>>>
>>>A suggestion for the WSRF group :
>>> * It would be helpful to know if specifying a resource identifier in
>>> the DAIS messages as well as in the header is acceptable to the WSRF folk.
>>>
>>>
>>>2. Multiple resources in a single request (see below for use cases)
>>>Currently, each DAIS service request accesses a single resource, and the
>>>resource being accessed determines the underlying resources that should
>>>be accessed too, e.g., the exposed single resource can perform resource
>>>name mappings . In this case, the WS-Resource concept may (or may not)
>>>be used to represent the exposed resources in DAIS. (depending on
>>>whether DAIS adopts WSRF)
>>>In some proposed extensions and applications of DAIS, multiple resources
>>>of different types are accessed through a single service request. It is
>>>required that the multiple resources be visible to the client. The
>>>WS-Resource concept could be used to represent a collection of
>>>resources. An identifier to represent the collection could be placed in
>>>the header, while the individual resource identifiers in the collection
>>>could appear in the message content.
>>>A note on resource properties:
>>> * Resource properties requests could result in properties for all
>>> the resources in the collection being examined. (see below for
>>> alternatives for representing the resource properties documents)
>>>
>>>A suggestion for the WSRF group :
>>> * It would be helpful to know if representing a collection of
>>> resources as a WS-Resource is a recommended use of WSRF.
>>>
>>>
>>>3. WSRF "WSDL 1.1 Binding Element Embodiment"
>>>If DAIS does adopt WSRF then the "WSDL 1.1 Binding Element
>>>Embodiment" is helpful because it permits a client supplied resource
>>>identifier to appear in the message header (in other words the resource
>>>identifier is not opaque to the client). However note that there are
>>>client side prerequisites for the "WSDL 1.1 Binding Element Embodiment",
>>>e.g., the client software would have to know to place the resource
>>>identifiers in the right place in the header
>>>A suggestion for the WSRF group :
>>> * It would be helpful to know if there are any tools that support
>>> embodiment "WSDL 1.1 Binding Element Embodiment"
>>>
>>>.................................................................
>>>
>>>Use Cases
>>>.........
>>>Here are some use cases for multiple resources in a single request:
>>>
>>>U1. In an interaction with a DAIS service, many resources may be created
>>>to represent the results of requests. There may come a time when
>>>several of these resources can safely be removed. In such a setting,
>>>the options are to:
>>>U1.1. Invoke something like "remove() => EPR representing resource" for
>>>each of the resources. U1.2 Invoke something like "remove([EPR
>>>representing resource-1, ...,EPR representing resource-n]) => EPR
>>>representing service" once.
>>>How would option U1.2 be modeled through WSRF?
>>>
>>>
>>>U2. In an interaction with a DAIS service, it may be necessary to
>>>aggregate multiple results sets and return the combined result set via
>>>ftp. In such a setting, the options are to:
>>>U2.1 Invoke something like "ftp (..) => EPR for resource1" for each of
>>>the resources and then aggregate the results on the client U2.2 Invoke
>>>something like :
>>>- "aggregate ([EPR representing resource-1, ...,EPR representing
>>>resource-n]) => EPR representing service" - "ftp (..) => EPR
>>>representing aggregated resource" (the result aggregation would be done
>>>at the server.)
>>>
>>>
>>>How would option U2.2 be modeled through WSRF?
>>>(BTW it is possible that a combined aggregate and ftp operation would be
>>>desirable)
>>>
>>>
>>>
>>>U3. In an interaction with a DAIS service, it may be necessary to issue
>>>a query over multiple databases and files. In such a setting, the
>>>options are to:
>>>U3.1 Invoke something like "query (..) => EPR for resource1" for each
>>>of the resources, returning each query result to the client, and then
>>>aggregate the results on the client
>>>(the result aggregation process could be very complex.)
>>>U3.2 Invoke something like "copy (..) => EPR for resource1" for each of
>>>the resources and then issue the queries locally on the client
>>>(this means having a query engine on the client.)
>>>U3.3 Invoke something like "query([EPR representing resource-1, ...,EPR
>>>representing resource-n]) => EPR representing service" once
>>>(the query result aggregation would be done at the server.)
>>>How would option U3.3 be modeled through WSRF?
>>>
>>>
>>>
>>>Alternatives for modeling resource properties documents for U1.2, U2.2,
>>>U3.3
>>>.............................................................................
>>><ResourceNames>
>>> <ResourceName>resource1</>
>>> <ResourceName>resourceX</>
>>></>
>>>
>>>Or as complex as
>>>
>>><Resources>
>>> <Resource>
>>> <ResourceName>resource1</>
>>> <ResourceType>RDB</>
>>> <ResourceSchema>....</>
>>> </>
>>> <Resource>
>>> ...
>>> </>
>>></>
>>>
>>>A suggestion for the WSRF group :
>>>It would be helpful to know which modeling approach is preferred
>>>
>>>
>>>Thanks to everyone who contributed and reviewed this note. Happy Happy
>>>Holiday Season :-)
>>>
>>>Susan Malaika
>>
>>_______________________________________________________________
>>Ian Foster www.mcs.anl.gov/~foster
>>Math & Computer Science Div. Dept of Computer Science
>>Argonne National Laboratory The University of Chicago
>>Argonne, IL 60439, U.S.A. Chicago, IL 60637, U.S.A.
>>Tel: 630 252 4619 Fax: 630 252 1997
>> Globus Alliance, www.globus.org
>
>_______________________________________________________________
>Ian Foster www.mcs.anl.gov/~foster
>Math & Computer Science Div. Dept of Computer Science
>Argonne National Laboratory The University of Chicago
>Argonne, IL 60439, U.S.A. Chicago, IL 60637, U.S.A.
>Tel: 630 252 4619 Fax: 630 252 1997
> Globus Alliance, www.globus.org
_______________________________________________________________
Ian Foster www.mcs.anl.gov/~foster
Math & Computer Science Div. Dept of Computer Science
Argonne National Laboratory The University of Chicago
Argonne, IL 60439, U.S.A. Chicago, IL 60637, U.S.A.
Tel: 630 252 4619 Fax: 630 252 1997
Globus Alliance, www.globus.org
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