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Re: Web Service Description and stateful services - (on the 'www-ws@w3.org' list) Debating on a) Stateful Web Service Instances b) Stateful Interaction - OGSI

From: Mark Baker <distobj@acm.org>
Date: Fri, 20 Jun 2003 10:21:44 -0400
To: www-ws-arch@w3.org
Message-ID: <20030620102144.U30095@www.markbaker.ca>

That sounds more like b) state; stateful interaction to me, Roger.

How about an example to explain the difference?

interface Lightbulb
{
  getState();
  setState();
}

This interface obviously deals in lightbulb state, which is what I
thought was meant by a) state.  Each service instance contains
information which represents the state of the lightbulb.

But, the interactions with each lightbulb are state*less*, because
each message contains all the information necessary to process that
message.

This would be an example of how to make that interface state*ful*;

interface Lightbulb2
{
  getState();
  setState();
  login();
  logout();
}

Now, a getState() message doesn't contain all the information necessary
to process the message, because some of that information is held by
the service itself; specifically, whether or not the user is logged in.
In order to make that interaction stateless again, the login info needs
to be in the message somewhere, ala;

  getState( userid, password );

MB

On Fri, Jun 20, 2003 at 08:54:07AM -0500, Cutler, Roger (RogerCutler) wrote:
> 
> This is certainly a different conception of maintaining state than what
> I am familiar with.  I think that the state maintenance I am familiar
> with does not refer to the lifetime of the entire service (like what
> geographic area a service supports), which I sort of thought would be
> part of the description of the service itself as opposed to anything
> about state.  Instead I think of state as being a characteristic of a
> series of invocations of services that are linked together into one
> "transaction" (loosely interpreted -- I am not talking about rollbacks
> and stuff here).  The state is then the collection of information that
> is necessary for a service somewhere in this chain to understand what
> the context of the invocation is.
> 
> Does that make sense?  Am I somehow out in the weeds on this?
Received on Friday, 20 June 2003 10:17:07 GMT

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