Re: [ws-caf-editors] als, context and compound protocols

["Mark Little" <mark.little@arjuna.com>]

I think the original intention was simply to model the context type through
XML "inheritence". However, it certainly wasn't fully thought out (like the
substitution group stuff). I think that we should do away with it and go the
a more uniform structure:

<ctx>
    <security>
    </security>
    <transaction>
        .... whatever this means
    </transaction>
</ctx>

It's more in line with other useages of context out there, and the
derivation mechanism doesn't buy us much (apart from the fact that maybe
conceptually it's nicer to be able to differentiate a transaction context
this way, but I'm not convinced).

Mark.

----- Original Message ----- 
From: "Greg Pavlik" <greg.pavlik@oracle.com>
To: "ws-caf-editors" <ws-caf-editors@lists.oasis-open.org>
Sent: Friday, March 26, 2004 9:09 PM
Subject: [ws-caf-editors] als, context and compound protocols


> Guys,
>
> I have spent some time trying to figure out how we can have both derived
> context types and multiple ALSes. Let me see if I can explain the
> problem clearly without writing a dissertation. Let me first layout my
> understanding/assumptions as to what happens according to the spec:
>
> 1) There is a ContextService that only knows about contexts of the
> namespace [context namespace]
> 2) The context service creates a generic activity and represents it by a
> context of ContextType defined in [context namespace] when an Begin
> operation occurs
> 3) following the creating of the "generic context", the ContextService
> implemenation invokes ALSBegin with the generic Context included as a
> SOAP header.
> 4) the ALS, as it stands, produces a new "augmented" context, of a
> derived type. I put augmented in quotes because this is a mutation
> occurence. For example, if this is the ACID protocol, the ALS is
> interested in producing a context of the type defined in the [acid
> namespace]. Have I got this right? (As an aside, what is one to make of
> the sync context, the 2pc context and the acid context? Do we really
> need more than one context type here?) I've always found this to be a
> little strange and it's unclear to me how this works well for the
> creation of nested activities. But let's assume for the moment it's
> correct and we nail down the specifics of how generic contexts
> communicate to the ALS they are a part of derived type parent context
> later. Then...
> 5) The ALS responds to the ContextService with the new augmented context
> of the derived type. This is the context that the ContextService now
> maintains on behalf of the activity.
> 6) The ContextService returns the new augmented context of the derived
> type to the caller with the Begun operation on the UserContextService.
>
> This may work, however, I'm unclear as to what exactly happens when
> there are two ALSes. How does this "mutation" mechanism work? Which ALS
> does the mutating? Does the first ALS do the mutating?
>
> In my implementation, I cheated and restricted the registration of an
> ALS to one per protocol. Is there a way around this? Do we really care
> about accounting for the set of all possible scenarios we can dream up,
> or can we as a first version try to make something that works well with
> this restriction?
>
> We're keen to move things along rapidly, so let's strive to come to a
> convincing conclusion on this matter.
>
>