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Subject: Re: [ws-caf] Mt Everest and WS-CF


Alastair, I'm happy to discuss climbing Everest in the context (no pun intended) of WS-CF iff that does not impede the progress of WS-Context.
 
Mark.
 
----
Mark Little,
Chief Architect, Transactions,
Arjuna Technologies Ltd.
 
www.arjuna.com
----- Original Message -----
Sent: Thursday, May 27, 2004 1:07 PM
Subject: RE: [ws-caf] Mt Everest and WS-CF

Mark,

 

I am not asking for anything to be revisited (at least fundamentally: if it turns out there are unturned model issues or bugs in WS-Context over time, I’m sure we will all be happy to entertain them).

 

I am content that WS-Context exists, and that you think it is valuable, while I question its value.

 

Like Mt Everest, it is there. That may not mean that I want to climb it.

 

My current concern is precisely the relationship between WS-Context and WS-CF, which you take as given, and which I wish the TC to question.

 

If you look again at my mail you will see that I am making two points, which I think you are missing.

 

1) I am not discussing whether to use by-value or by-reference. I am discussing whether to use WS-Context at all. (I assume by-reference is idiosyncratic with respect to WS-CF etc; I see no proven worth in WS-Context-by-value over plain old SOAP header elements.)

 

2) I am specifically raising whether WS-CF should reference WS-Context, or whether it should not reference WS-Context. I see no need for WS-CF to do so, and I believe that doing so causes unnecessary complexity and implementation effort for WS-CF and WS-TXM. The relationship is artificial.

 

I believe that the model of WS-Coordination and its relationship to the coordination protocols in the WS-Transaction family is correct; that is to say – all that is required. We should apply Occam’s razor here. If in the mists of the pre-history of WS-CAF and WS-C+T IBM and Microsoft sheared away the predecessor of WS-Context, then I think they were right to do so (for the purposes of defining coordination protocols).

 

In addition, and with reference to the political concerns you raise about impeding adoption:

 

3) I believe that if other standards bodies adopt WS-Context then they are probably not looking hard enough at the value they will obtain by doing so. The tough job is to define the content, nature and meaning of context information for a particular higher-level protocol; not to define a generic wrapper element to hold all such contexts, nor to define an interoperable factory interface.

 

Alastair

 

PS It is always a good idea, as Peter points out, to justify the existence of a specification in the specification or accompanying material.

 

-----Original Message-----
From: Mark Little [mailto:mark.little@arjuna.com]
Sent
:
27 May 2004 11:42
To: Green, Alastair J.; ws-caf
Subject: Re: [ws-caf] Mt Everest and WS-CF

 

Alastair, I understand why you may want to revisit this, but obviously disagree and don't want the TC process to be unduly stalled. I cannot see what adverse effect going forward with the specification as it currently stands has on any referencing specification that decides not to use context by value but instead chooses context by reference (and vice versa). It does neither impinges on the readability of the specification nor on the understandability IMO.

 

I re-iterate that I believe we have already discussed this subject over the past 2/3 months in teleconferences and face-to-face meetings. I don't believe that revisiting it will benefit us or the WS-Context specification at this stage. What it will do is delay the adoption of WS-Context by other interested groups and by other referencing specifications (e.g., WS-CF). I see that as a big disadvantage.

 

Mark.

 

----
Mark Little,
Chief Architect, Transactions,
Arjuna Technologies Ltd.
 
www.arjuna.com

----- Original Message -----

Sent: Thursday, May 27, 2004 11:28 AM

Subject: [ws-caf] Mt Everest and WS-CF

 

Hi Mark,

 

You pointed the list at an interesting document by Savas et al. I commented upon it, as did Peter upon the interop demo, because it illustrates a fundamental issue for any potential user of WS-CAF: what is the worth of WS-Context context-by-value?

 

The argument for this feature seems to resemble the motivation for climbing Mt Everest: “because it’s there”.

 

I don’t think that this question can be circumvented, and it is relevant to WS-CF. Should WS-CF have a necessary dependency on WS-Context? After all, WS-Coordination manages to create a generic tree-building (address-exchange) protocol without use of a layer like WS-Context. I think this is a better model. Then those who wish to wrap context information in standard wrappers can do so (use WS-Context), and those who don’t wish to do so, don’t need to (ignore WS-Context as adding little real value).

 

My interest in this is far from academic. If WS-CAF transaction or coordination protocols gain traction at some future date, then I would like to make our engineers’ lives as easy as possible, by streamlining the work needed to the strictly necessary (after all, it will only be the third set of two-phase outcome protocols we have to add to our product, in order to accommodate the jostling of the software industry majors). I cannot see how WS-Context contributes to WS-CF or WS-TXM.

 

Incidentally, I made no mention of context by reference. I view this as an interesting possibility fraught with problems, which I predict will not be widely used. Every example of WS-Context use that I see discussed uses “by value”. I certainly think that coordination protocols need by-value contexts (which of course can be carried in SOAP headers directly).

 

Alastair

 

-----Original Message-----
From: Mark Little [mailto:mark.little@arjuna.com]
Sent: 27 May 2004 10:20
To: Green, Alastair J.; ws-caf
Subject: Re: [ws-caf] interesting document

 

Alastair, is this interesting for a purely academic standpoint? I believe that the TC already discussed these issues and voted on them, so it seems like going back over old stuff to me. To summarise what this TC already agreed on, since we neither mandate context-by-value nor context-by-reference in the base-line context document, it is up to referencing specifications to determine which format they wish to use. I think that arguing this again is not going to be fruitful and I'd like to see this TC move on to the coordination specification (which was agreed at New Orleans).

 

Mark.

 

----
Mark Little,
Chief Architect, Transactions,
Arjuna Technologies Ltd.
 
www.arjuna.com

----- Original Message -----

Sent: Wednesday, May 26, 2004 6:03 PM

Subject: RE: [ws-caf] interesting document

 

I have to believe I'm missing something or being plain stupid, but here goes ...

 

It would be interesting, in light of Peter's recent mail on the value of WS-Context context-by-value, to examine what would change in these scenarios if the <ctx:context/> were to be replaced by a simple SOAP header element. Strip out <ctx:context/>, replace the placeholder "context state" with <protocol:context/>, place this element in the SOAP header, and proceed. This would be a less restrictive, but I believe legal, use of WS-I (i.e. move protocol-specific context info from body to header).

 

It would also be interesting to consider, in the light of Jim and Guy's exchanges, what role activity completion plays, if any? Activity completion can only be communicated to context recipients if they are registered with the context service that knows that the activity is now complete. WS-Context does not define such a registration-notification mechanism. This continues to leave in question the independent value of WS-Context context-by-value. This type of functionality must reside in the surrounding protocol (session, coordination etc) that in my example is denoted by the namespace URI indicated by the prefix "protocol" (the "referencing specification"). An example of such a protocol is WS-CF, or in truncated form, WS-Coordination.

 

As there is no bundle of contexts specified by WS-Context (if my understanding has kept pace with the spec changes), the argument that value is provided by easing interception (simpler to identify the group of contexts that must be processed by a set of interceptors), becomes a non-argument.

 

Where does this leave the independent value of WS-Context context-by-value?

 

These points are orthogonal to the issue: header element in the raw, body element in the raw, or element embedded in an address.

 

Alastair

-----Original Message-----
From: Mark Little [mailto:mark.little@arjuna.com]
Sent: 26 May 2004 16:45
To: ws-caf
Subject: [ws-caf] interesting document

 

And Savas is a member of this TC (though I don't think he's ever attended any of the teleconferences ;-)

 

Mark.

 

----
Mark Little,
Chief Architect, Transactions,
Arjuna Technologies Ltd.
 
www.arjuna.com



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