RE: Compositions Types:Static and Dynamic

Daniela,

Thanks very much for your kind advice and discuss. To my opinion, dynamic
composition may be a part of the service discovery and matchmaking process.
Semantic information is useful in such situation. Dynamic invocation,
however, may have to deal with programming issue.

So when we know the composite process of a service chain, how can you
dynamically invoke each of the services described in your composition
document? Given the example that you know the WSDL URLs and IOPEs for both
Microsoft's TerraService and ESRI's address geocoding services, you know you
have to first use the "address" information to invoke geocoding service to
retrieve lat/lon values, which will then be used to invoke TerraService's
function to retrieve the image you want. How can you invoke the service
through composition? 

I know even it's a difficulty and complex process to create/deploy a static
java Web service, but did not try dynamic invocation in java. However, I do
know how to dynamic invoke a WS in .NET in the proposed OSRR approach which
is much much better and convenient than the traditional WSDL-based dynamic
invocation-a difficulty for such task.

Best wishes,

Xuan


-----Original Message-----
From: Daniela CLARO
To: public-sws-ig@w3.org
Sent: 4/26/06 4:11 AM
Subject: RE: Compositions Types:Static and Dynamic


Hi Xuan, 
  

> 
> One more question is about the relationship between dynamic 
> service composition and dynamic service invocation. If the 
> purpose of dynamic service composition is for dynamic service 
> invocation, given the example of retrieving an aerial photo 
> from Microsoft's Terraservice, how such dynamic composition 
> will enable the dynamic invocation? 
For me, one think is dynamic composition, i.e. when your goal is to
construct a stair(ws1) and for this you need to supply the
concrete(ws2). However the ws2 (supply concrete) you do not know yet.
Thus the dynamic composition is responsible to put the ws2 in your
composition to achieve the goal 'create a stair'. On the other hand,
dynamic invocation, we can have already done dynamic composition, and at
the moment you will execute these services w1 and w2, the w2 is offline.
Thus you should find another service, with the same functionalities to
replace the ws2. 

Thus we can have dynamic compositions and dynamic invocations or both!
This is my point of view :o)! And most of the papers in planning, as I
could observe, treats dynamic invocation. Actually I do not know if they
treat dynamic composition also, do they? 


>In this case, the known 
> WSDL documents can be identified, thus you know the IOPEs for 
> this task. 
Yes... 
> I never tried the dynamic invocation in Java, but in .NET, I 
> know it's a difficulty to build dynamic invocation in the 
> traditional WSDL approach.
I think dynamic invocation as people are doing, as I have read in some
papers is using planning and semantic web, because how you will find
other services, with the same functionalities (and probably others
non-functional criteria as QoS) without semantics, it will be more
difficult. Thus many approaches are using planning with semantics. The
paper Template-based Composition of Semantic Web Services E. Sirin, B.
Parsia, J. Hendler used a planner based on Java, the Jshop. 

I created a planning algorithm using a rule-based engine, called JESS.
It not efficient as a planner with relaxed restrictions as a HTN, but we
should start by something! JESS is completely integrated with Java.
JSHOP I do not know, but the authors can say something about it! I
created a dynamic composition and not a dynamic invocation. In my
invocation I consider that everything works fine!

Hope that helps,
Daniela

Received on Wednesday, 26 April 2006 15:10:04 UTC