RE: combined proposal for issues 8180, 8299, and 8302 (fwd)

(bounced because of attachment size, compressed version attached)

-- 
Baroula que barouleras, au tiéu toujou t'entourneras.

         ~~Yves

---------- Forwarded message ----------
Date: Wed, 27 Jan 2010 15:20:47 +0000
From: Ram Jeyaraman <Ram.Jeyaraman@microsoft.com>
To: Gilbert Pilz <gilbert.pilz@oracle.com>,
     "public-ws-resource-access@w3.org" <public-ws-resource-access@w3.org>
Subject: [Moderator Action (size limit exceeded)] RE: combined proposal for
     issues 8180, 8299, and 8302

Gil, thanks for the proposal.

Thinking about the basic model, I wonder about what does it mean to null out a resource.

Here are some possible representational states of a resource:

1.        Has non-empty representation ? that is , ?a?.

a.       Resource exists

2.       Has empty representation ? that is, ??.

a.       Resource exists

3.       Has no representation ? that is, null.

a.       Does this mean that the resource does not exist or it exists in a default form (representation)?

Now, let us explore the semantics of using the possible representational forms within the various Transfer operations.



Non-empty representation (?a?)

Empty representation (??)

Null representation (null) [assuming resource does not exist]

Null representation (null) [assuming resource exists in default form]

Create

Creates resource with representation ?a?

Creates resource with representation ??

What does it mean to create a resource that is null or non-existent?

Creates resource with a default representation.

CreateResponse

MAY return representation ?a?

MAY return representation ??

What does it mean to return a null or non-existent resource?

MAY return default representation. What would this representation look like? <wst:Resource/>? Or would it have some default values?

Put

Updates resource with representation ?a?

Updates resource with representation ??

What does this mean to null out or make a resource non-existent? Isn?t this same as deletion?

Updates resource with default representation

PutResponse

MAY return representation ?a?

MAY return representation ??

What does it mean to return a null or non-existent resource?

MAY return default representation. What would this representation look like? <wst:Resource/>? Or would it have some default values?

Get

N/A

N/A

How is it even possible to reach a non-existent resource?

N/A

GetResponse

Returns representation ?a?

Returns representation ??

What does it mean to return a null or non-existent resource?

Returns default representation. would this representation look like? <wst:Resource/>? Or would it have some default values?

Delete

N/A

N/A

N/A

N/A

DeleteResponse

N/A

N/A

N/A

N/A


We need to decide on the semantics of the null representation. Does it mean that the resource does not exist or it exist with some default representation?

Thanks.

From: public-ws-resource-access-request@w3.org [mailto:public-ws-resource-access-request@w3.org] On Behalf Of Gilbert Pilz
Sent: Tuesday, January 26, 2010 11:30 PM
To: public-ws-resource-access@w3.org
Subject: combined proposal for issues 8180, 8299, and 8302

To summarize the positions on the basic issues:

8180:
Yes, resource representations can be "empty", i.e. "have no value". Empty resources are created by supplying a <wst:Representation/> in Create. The existence of an empty resource is indicated by a Get that returns a <wst:Representation/>. Resources can be "made empty (i.e. have their representation removed) by Put-ing a <wst:Representation/>.
8299:
The ambiguity between representation and extensions has been removed by the introduction of the wst:Representation element. The XML element inside a wst:Representation is the representation. Anything outside the wst:Representation element (and in a different namespace that WS-T) is an extension. This is described without complicated language on the optionality of representation etc.
8302:
I believe this is significantly clearer and more straightforward than previous versions. The use of the "implicit Get" operation is described in straightforward way that allows for it to be used in a multitude of situations but does not require services to perform onerous tasks such as transmitting very large messages in response to very large requests.
- gp