RE: [wsrf] Issue WSRF9

["Murray, Bryan P." <bryan.murray@hp.com>]

Title: Message

I think in many cases, a "display the properties and values" application can display a set of properties without knowing the cardinality.

 

Bryan

-----Original Message-----
From: Steve Graham [mailto:sggraham@us.ibm.com]
Sent: Tuesday, June 22, 2004 10:57 AM
To: Murray, Bryan P.
Cc: wsrf@lists.oasis-open.org
Subject: Re: [wsrf] Issue WSRF9

I agree with Bryan that the "display the properties and values" is the most "obvious" use case to suggest some sort of runtime support for additional meta-data on "dynamic" resource properties.  There may be other use cases, but  I again agree with Bryan's observation of the need for the application to have a-priori understanding of the semantics of those resource properties.

So, in the case of "display the properties and values" the application would need to know not only the xsd details of the GED (eg type), but also the cardinality of the resource property use of the GED (minOccurs and maxOccurs).  The xsd details of the GED can be found (via WS-MetaDataExchange, for example).  It is the cardinality (and maybe other details) of the resource property that need to be discovered.

sgg

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Steve Graham
(919)254-0615 (T/L 444)
STSM, On Demand Architecture
Member, IBM Academy of Technology
<Soli Deo Gloria/>
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"Murray, Bryan P." <bryan.murray@hp.com> 06/21/2004 01:07 PM

To:        <wsrf@lists.oasis-open.org>         cc:                 Subject:        [wsrf] Issue WSRF9

                 I understand the need to know which properties are currently
present
                in the property document given that the property document
supports
                dynamic properties. However, I would like to see a use-case
describing
                the need to retrieve at runtime the schema for any properties.

                The only reason I can think of for retrieving properties which
an
                application does not already understand is if the application
simply
                displays properties to a human or copies the property somewhere.
If
                the application understands the namespace of the property it can

                locate the type from the WSDL/schema for the namespace.
Otherwise,
                simple properties (no child XML elements) can be displayed
without
                understanding their type by just treating the text node as a
string.
                The application can choose to either not display complex
properties or
                to list attributes and child elements with their values.
Grandchild
                elements or attributes will ultimately make this too complicated
to do
                at some point.

                Other, more complex, applications will need to understand not
only the
                syntax of the properties they are retrieving, but also the
semantics
                of those properties in order to interact with them
appropriately. The
                syntax can be found in WSDL/schema files, but the semantics
needs to
                be understood by the programmer writing the property retrieval
code. I
                am confused as to how an application could interact with a
property it
                does not understand beyond simply displaying or copying its
value. If
                an application does understand a property that falls into the
xsd:any
                portion of the resource property document schema, it does not
need the
                schema - it already knows the type of this property.

                If there is no need beyond displaying or copying the value of an

                unknown property I suggest that we not provide the ability to
retrieve
                the schema at runtime.

                Can someone offer a use-case that shows where my thinking is
                deficient?

                Bryan