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Re: what is discovery - One concrete proposal

From: Heather Kreger <kreger@us.ibm.com>
Date: Fri, 11 Oct 2002 08:01:10 -0400
To: "Jean-Jacques Moreau" <moreau@crf.canon.fr>
Cc: www-ws-arch@w3.org
Message-ID: <OF38CA4A91.B0D5C5F4-ON85256C4F.0040F606@us.ibm.com>

Discovery can be done before the client is developed, while the client is
being developed (hence it is pre-compiled in). This is the most common
scenerio being deployed today.  In IBM we call this static binding.

Discovery can also be done by the client at runtime. There are two types of
runtime binding:
1. The client has already discovered the interface, has programmed to it,
and just the service instance (location from the WSDL) is discovered at
runtime. This scenario is being deployed today, but less often than static
binding.  WSIF supports this type of binding.

2. The client discovers the interface specifics and the service instance
during runtime. In the deployments of this that I know of, they use a DII
style interface, like the JAXRPC call object or the WSIF apis to figure out
what message to create, create it and process the results.  There are not
many of these out there.

Heather Kreger
Web Services Lead Architect
STSM, SWG Emerging Technology
919-543-3211 (t/l 441)  cell:919-496-9572

"Jean-Jacques Moreau" <moreau@crf.canon.fr>@w3.org on 10/11/2002 02:42:42

Sent by:    www-ws-arch-request@w3.org

To:    Dave Hollander <dmh@contivo.com>
cc:    www-ws-arch@w3.org
Subject:    Re: what is discovery - One concrete proposal

A SOAP client may use a service where the service information is
obtained out of band (e.g. it may be precompiled into the
client). Is this supported by your current definition or are you
implying that discovery is mandatory (I don't read anything like
discovery is optional)?


Dave Hollander wrote:
> To try to get temporary closure on the discovery,triangle,
> and cloud, let me try to state one position.
> Recommendation:
> 1. Leave it in the spec dract as is or ammended with axioms
>    from below.
> 2. Add an example where "discovery" is a trivial role because
>    there are two parties directly exchanging information that
>    is hardwired into the service.
> 3. Label the node "Discovery Agencies"
> --------------------------------------------------------------
> Discovery = exchange of the service description details necessary
> to make a conncection.
> Discovery Axioms:
> 1) discovery need not rely upon formal documents.
> 2) discovery occurs regardless of when the discovered
>     information is bound into the connection (early or late).
> 3) discovery is discovery regardless if the provider or
>     requestor does the advertising.
> 4) discovery is discovery even if the data discovered was
>     already known. All that needs to be true is the potential
>     that the data *may* be different or new.
> 5) discovery is discovery even if there are only two parties,
>     requestor and provider.
> I believe that "discovery", as defined above, exists as a
> role in all of the scenarios that have been presented here.
> So that leads to the question: is "discovery", as defined above,
> relevent enough to be included in our base architecture?
> I believe discovery is relevent and should be in the
> base architecture for the following reasons:
> 1. the distinction between hypertext and web services
>    web has hypertext links to create a network, web
>    services currently do not have a mechanism for defining
>    a newtwork.
> 2. good for the "ilities" (scalability, reliability, etc)
> 3. it always happens, just sometimes it is done outside
>    of the system.
> 4. Most people expect to see it. If it is not there, our
>    audience will either be disappointed or will try to find
>    it. Either way confusion and mixed understanding will result.
Received on Friday, 11 October 2002 08:01:54 UTC

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