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Subject: RE: [wsrf] Identifying WS-Resources: ReferenceProperties or ReferenceParameters?
Here is an extract from an
article
than
throws some light on when to use reference properties and reference
parameters.
"The distinction between reference
properties and reference parameters is in how they relate to a service's
metadata. The policy and contract of a Web service is based on its base address
and reference properties only. Typically, the base address and reference
properties identify a given deployed service and the reference parameters are
used to identify specific resources that are managed by that
service.
There
are many uses for reference properties. Two simple examples are classes of
service and private entity identifiers. In the class of service example,
reference properties may be used to differentiate between a Web service for
standard customers and one for "gold" customers that provides a higher quality
of service and enhanced capabilities, logically forming two different endpoints.
Properties such as these are set only once in a session and then reused
throughout the rest of the interaction.
An
example of a second kind of use of a reference property is a mechanism to
identify a customer in a manner private to the originating system.
A
combination of these two types of reference properties could enable efficient
message dispatch to the appropriate collection of servers and efficiently
finding the application state that relates to a particular user. These examples
also show how data that refers to instances of services and data that refers to
instances of users can be represented in reference
properties.
Two
kinds of uses for reference parameters are infrastructural and
application-level. An infrastructural example of a reference parameter can be a
transaction/enlistment ID sent to a Transaction Processing monitor. In a
book-purchase scenario, the ISBN number of a book can be an application-level
example of a reference parameter."
Hi Steve I copied and pasted into a new thread since it looks this topic belongs on its own. Steve Graham wrote: Isn't this then in contradiction with the new WS-Addressing spec that suggests "A consuming application should assume that different XML schema, WSDL definitions and policies apply to endpoint references whose address or reference properties differ"? The way it is used now, we have different referenceproperties associated with the same schema, wsdl and policy. I concluded from the above statement that referenceproperties are used to allow the use of the same address by many different services (endpoints) (potentially different in schema, wsdl or policy). An example is a load balancing service that is a front for a server farm where different requests are routed to different machines depending on their policy requirements for example. Now where does the reference parameters come in. The spec says [reference parameters] : xs:any (0..unbounded). A reference may contain a number of individual parameters which are associated with the endpoint to facilitate a particular interaction Each enpoint in the server farm can additionally use reference parameters to identify/disabiguatre WS-resources (subscriptions for example). So we have some sort of two level referencing. The first allows the use of one adress by many endpoints and the second allows the use of one endpoint by many ws-resources. Abdeslem /////////////// |
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