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

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

Dan,

 

The purpose of RMD has always been to be an aid to applications wishing to interact with resources of the type specified in the RMD doc. The doc helps applications format messages, especially messages that modify the resource representation, with values that the resource is likely to accept.

 

The RMD descriptions were intended to be an advertisement of what the service already does. They are not meant to cause the service to check ranges or make sure that received values are listed in the RMD doc. There is no runtime enforcement implied by any data in an RMD doc. Just because you change data in an RMD doc does not imply that the service is going to behave any differently than it did before the modification.

 

The RMD doc does not contain nearly enough information to be a general purpose deployment specification. I don't understand why we would try to add some small details about deployment at this late date when we are not providing enough other information in this doc to perform deployment.

 

I recommend that details such as initial value be put in a document intended for deployment, and that we not include it in the RMD specification.

 

Bryan

 

---

From: Daniel Jemiolo [mailto:danjemiolo@us.ibm.com]
Sent: Thursday, April 06, 2006 1:23 PM
To: Murray, Bryan P.
Cc: wsrf@lists.oasis-open.org
Subject: RE: [wsrf] Proposed resolution - re: InitialValues for properties in WS-RMD

Bryan, 

You are correct that the initial values have no relevance 
to the client. However, I think that the use cases of this spec are not limited 
to introspection by clients. RMD can also be used by resource implementations to 
initialize WS-RP documents and enforce metadata for some or all properties 
(depending on how/where the properties are stored). It's a case of wanting to 
reuse an artifact we already have rather than inventing something that's 
implementation-specific. 

For 
example, if you had an IDE that allowed you to design and generate WS-* 
interfaces and the many artifacts that are required to deploy them, you could 
use the RMD document (and other artifacts) to automate parts of the WS-* 
configuration at runtime. This type of automation allows programmers to focus on 
their custom resource/manageability logic and less on enforcement of basic 
WS-concepts and plumbing. 

Also, Kirk 
is correct - the term "default" values is semantically inaccurate. I will stick 
to "initial values". 

Dan

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

04/06/2006 03:20 PM

To	Daniel Jemiolo/Durham/IBM@IBMUS, <wsrf@lists.oasis-open.org>
cc
Subject	RE: [wsrf] Proposed resolution - re: InitialValues for properties in WS-RMD

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. +++