Re: [wsrf] Proposed resolution - re: InitialValues for properties in WS-RMD

[David Snelling <David.Snelling@UK.Fujitsu.com>]

Folks,

The use case of using the metadata descriptor to assist with the  
deployment of services was always one of the advantages of having it  
as a separate document (as opposed to the integrated approach used in  
OGSI). I realize that the introduction is not very strong on this  
point, it it does say,

> The second purpose is to provide information about the value  
> restrictions of the resource properties in the resource properties  
> document for the WS-Resource. This additional information may be  
> associated with implementations of the interface as well as with  
> the WSDL interface definition.

This is certainly not a new idea, but was indeed something dropped  
somewhere along the way. I think we should put it back in.

This helps the client as well. There will frequently be a number of  
properties that are not mutable. At design time a client could preset  
these and not have to query for them, but only if the initial values  
were included in the design metadata.

Also: The multiple Initial Values allow for the initialization of  
properties with maxoccurs greater than 1.




On 6 Apr 2006, at 20:20, Murray, Bryan P. wrote:

> Dan,
>
> I will add this issue as you wrote it to the issues list.
>
>
> My comments on this issue:
>
> Maybe I am getting confused by the terminology, but to me something  
> called "initial" values in a metadata document would not be  
> modified, added or removed over time. The initial values would be  
> used to initialize properties when a resource was created. After  
> creation, the initial values metadata has no further use. The  
> current value of the resource properties are available from the  
> resource, but the initialValue metadata has no meaning once the  
> resource has been created. With this understanding of the  
> semantics, this metadata has minimal value to a client interacting  
> with a resource having these initial values, as an instant after  
> creation the resource is running and having its values changed to  
> reflect the state of the resource.
>
> What am I missing? I don't understand how the initial values is  
> useful to a client. The metadata is only an advertisement about the  
> service, but why advertise something that has minimal value?
>
> Bryan
>
> From: Daniel Jemiolo [mailto:danjemiolo@us.ibm.com]
> Sent: Thursday, April 06, 2006 11:40 AM
> To: wsrf@lists.oasis-open.org
> Subject: [wsrf] Proposed resolution - re: InitialValues for  
> properties in WS-RMD
>
>
> On the TC call on 4/3/06, I proposed that we (re-)add the concept  
> of initial values to the WS-RMD spec. This issue does not have a  
> number yet. Below is a description of the issue and the proposed  
> resolution.
>
> When programming against the RMD spec, it is often necessary to  
> seed a property with a set of initial values that are known at  
> design time. A better term might be "default" values. The  
> difference between these initial values and the concept of static  
> values already in the spec is that initial values should be  
> mutable, while static values are not.
>
> The definition of initial values in an RMD document would be just  
> like that of static values. For example, a property named  
> MyProperty of type integer might have the following definition:
>
>
> <wsrmd:Property path="myns:MyProperty" ... >
>    <wsrmd:InitialValues>
>       <myns:MyProperty>123</myns:MyProperty>
>       <myns:MyProperty>456</myns:MyProperty>
>    </wsrmd:InitialValues>
> </wsrmd:Property>
>
>
> If the property is mutable, these initial values may be deleted or  
> updated over the resource's lifetime. Again, this is different from  
> static values because even on mutable properties, static instances  
> are never deleted or updated.
>
> The proposed resolution is to add the initial values concept to RMD  
> by copying the section on static values (8.4), doing a search-and- 
> replace (StaticValues -> InitialValues), and modifying the two  
> introductory sentences to describe the role of initial values. The  
> schema and infoset figures (in section 8 and appendices) will also  
> need to be updated to reflect this option.
>
>
>
>
>
> Dan Jemiolo
> IBM Corporation
> Research Triangle Park, NC
>
>
> +++ I'm an engineer. I make slides that people can't read.  
> Sometimes I eat donuts. +++
>

Take care:

       David Snelling David . Snelling . UK . Fujitsu . com
       Fujitsu Laboartories of Europe