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Ron,
There are no tools I am aware of that are designed to
author or enforce such contracts, so your quest is probably premature. Anything
you will find will likely be experimental at best. The standards aren't even
there yet, although WS-Policy and OWL-S specs may form the basis for future work
on the subject.
While you correctly state that WSDL may be a part of a
contract, the WSDL itself is an offer (or part of an offer) on the part
of a service provider. Same goes for WS-Policy and OWL-S, which represent
just what the provider declares. A real contract signifies an agreement between
2 or more parties and thereby needs to include at least one service consumer.
BPEL is perhaps a better example of a contract, which in fact leverages
WSDL. In many cases a bilateral contract will be identical to the service
provider's offer, but it may not be so simple in all cases. Semantics may vary
depending on context (identity of consumer, relationship with provider,
conversation state, etc.), which BPEL allows to capture to an
extent.
Regards,
Daniel
Yes, I made that point in my email. WSDL is not sufficient to
describe functional and non-functional requirements in the contract. If it
was, I wouldn't need to ask for examples ;) So, now I'm asking the question:
does ANYONE have examples for real-world Service Contracts?
Jason and I
have been pounding the ground on this question for about 3 weeks now in
different forums, and it seems that remarkably, there are very few, if any,
real-world examples of Service contracts other than the aforementioned, but
drastically insufficient WSDL.
So - once again - this is the time for
those on this board to show their mettle. Anyone have any real-world Service
contracts that handle non-functional and functional requirements? We've got
lots of theorists, pundits, and advisors on this group, but where are the
practical implementers?
Ron
Awel Dico wrote:
Hi Ron;
I
agree that WSDL is not sufficient to provide all metadata
associated
with security, semantics, QoS, SlA ..etc. I don't think
WSDL is supposed
to provide those semantics either. As for security
within the SOA
context, the message level security that can be
defined in SOAP headers
(as defined in WS-security) is not
sufficient. The SOA infrastructure
needs to provide another level of
security, such as authorizing the
client, for the access of the
service (i.e. before sending the actual
soap request - client
request is accepted only after the autorization is
passed and then
the message level security could take over). For this to
happen some
sort of security policy need to be implemented external to
the
service that WSDL describes. May be XML appliences could help on
this.
As to service semantics, this is a challenge because
trying to add
semantics to WSDL requires establishing good data
semantics. I think
we have long way to go to tackle semantcs part in
standard way. For
now tactical solutions in development team communicate
some data
semantics external to WSDL.
QoS ans SLA is something
that is responibility of the SOA
infrastructure rather than at the
service (wsDL) level. I think
this requires some sort of service
management tools for monitoring
and managing services based on policies
published in Service
registry tools. may be WSDM standard helps on this.
Again, defining
SLA within WSDL for client consumption, I think, may not
be
practical.
When you say "process", I assume you mean business
process here. In
that case, BPEL is used to describe the business
process. Each
service described in WSDL can be orchestrated using BPEL
to
implement higher level business service (i.e. business
process).
I know I am not helping you as such with your question -
since you
ask for real example contract that handles these items. I am
just
trying to point out that all those tasks are not in the scope of
WSDL and that other SOA infrastructure elements and polices are
required.
Regards,
Awel Dico
--- In [email protected],
Ron
Schmelzer <[EMAIL PROTECTED]> wrote:
> Hi
All --
>
> As you all know, one of the key parts to making
loosely coupled
Services
> work is a well-defined contract that
identifies both functional as
well
> as non-functional
requirements for Service providers and
consumers. By
> now, you
also probably realized that WSDL by itself is not
sufficient to
>
provide all the metadata needed for loose coupling and late
binding.
> Other metadata are needed including security, semantics, QoS, SLA,
> process, etc.
>
> So, what we are looking for are
actual examples of real-world
contracts,
> or templates for
contracts that you are using in real-world SOA
> deployments, or at
the very least, guidance for how those
contracts can
> be
defined.
>
> So, help anyone?
>
> Thanks in
advance!
> Best,
> Ron
>
> --
>
_____________________________________________________________
> Ronald
Schmelzer
> [EMAIL PROTECTED]
> Senior Analyst
> ZapThink
LLC
> Direct: 781-577-2779 / Main:
781-207-0203
--
_____________________________________________________________
Ronald Schmelzer
[EMAIL PROTECTED]
Senior Analyst
ZapThink LLC
Direct: 781-577-2779 / Main: 781-207-0203
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