web service composition simulator

[Hhamid63]

I am a student of electrical engineering and my thesis title is as follow:
"Design a QOS-aware web service composition algorithm in a service-oriented environment".

Here comes the problem.
I designed an algorithm for this issue but I have no idea:
1. How can I simulate my algorithm?
2. How can i get some real web services for making a service repository?

The aim of the simulator is to extract some parameters from a service request as inputs and bring back a composite web service which fulfill all the request's needs. first, components of the composite service must be discovered from service repository, then an execution flow for these components should be generated. through this, I want to evaluate the proposed algorithm in a manner of time consuming and accuracy.

Can anyone point me in a right direction?

[RedSon]

Describe a use case for me, I'm afraid I haven't the faintest idea what you are talking about.

[Hhamid63]

Hi my friend,
appreciate for your concern about my question. can I have a little information about you and your scientific field?
I think it can help me to explain my problem unambiguously to you.
my profile:
my name is Hamid, 25 years old from Iran, Tehran. studying electronic engineering in Iran University of Science and Technology for MS degree, last semester and stuck in my thesis thing.
my research interests include Reconfigurable processors, grid computing and Semantic web researches. Unfortunately, I am fresh in the latter one that my thesis is about.

[RedSon]

I have a similar history to you, but I'm not from Iran. Now, please explain a use case or describe what a "a QOS-aware web service composition algorithm" is and then we may be able to discuss implementation details.

[Hhamid63]

In the service-oriented environment there are some needs (from the clients) that can't be fulfill with a single web service. Web services are autonomous applications that can be invoked through the web and interact with each other through a piece of standards like SOAP. These web services also can be used as a building blocks to compose a value added composite services.(for more details, please study a little about web service technology and SOA).
Motivation example:
a client wants to have a trip from L.A. to NY. his/her needs are as follow:
1. flight ticket reservation
2. hotel reservation in NY
3. hiring out a car in NY
4. ......
There is no single web service to do all these. so, there must be a service broker who recieves this request and compose a composite web service from services available in the service repository. Therefore we need a web service composition algorithm for this. There are two kinds of algorithm: automatic and manual. My algorithm is automatic.
First, web services needed for the request must be discovered from web service repository, then an execution flow must be generated for addressing the sequence of execution of these web services. this was a brief actions of the algorithm. By Qos-aware I mean for discovering web services from the service repository, service broker considers their Quality Of Service. Now I designed such a algorithm and the problem is that I don't know how can I simulate the algorithm?
These algorithms are evaluated by the factor of time consumed for composing a composite web service, because these are real-time algorithms. The simulator should implement the algorithm for a typical request over a real WS repository and calculate time needed for this process and finally plots a diagram (time as Y and number of WS available in the service repository as X) for comparing the algorithm with the existing.
If there any question, please ask a detailed one. You know, WS composition algorithm is a long story and I can't explain all these in a few paragraphs.

[RedSon]

How do you calculate the QoS of a given web service? Are you talking about average latency?

When you discuss a "simulator" are you discussing creating a simulated service repository where each service provider has a quality of service value attached to it?

[Frinavale]

@RedSon
I think Hhamid63's talking about how fast a composite web service could be generated based on the web services that were used to create it....I think.

Or maybe he's talking about the latency of the web services in the composite webservice?

At this time I'm unaware of anything that creates composite web services like Hhamid63 talking about.

Hhamid63, are you creating a system that does this? Or are you testing a system that's already in developed?

@RedSon
If you're looking to test on a real world repository try something like xmethods.net. I'm not sure how well this type of testing is going to go on a real world repository though. Many of the web services listed in these types of repositories require you to pay order to use them. It's very likely that your simulator's going to fail on a lot of the web services in the repository.


-Frinny

[Hhamid63]

My algorithm didn’t implement yet but there are many algorithms implemented like this in research level not real world.
Yes, Frinavale is right. I’m talking about time criticality of composition algorithm. In the first step, my assumption is that the QOS of each web service provided by it’s provider and located in the WSDL file. My algorithm’s focus is on WS discovery unit where all components of composite WS must be discovered from WS repository according to given service request in a way that maximum QOS for composite WS achieved. So, algorithm is seeking for:
1. Functional aspect, that means the composite WS must fulfills all the request’s needs.
2. Non-functional aspect (QOS), that means composite WS must has the maximum QOS.
Major intention of simulation is to calculate the time needed for such a process to figure it out that does it have the ability to act as a real time algorithm or not.

[Frinavale]

I'm sorry but I'm not entirely clear on what the problem is here.

Your system sounds like it is going to be fun to implement...

But most of the time the developer knows what web services their application is going to be using and uses them. And there's a few things right off the top of my head that I see wrong with relying on speed as the "quality of service" test...

But I guess for academic purposes this sort of thing is ok....

Anyways, back to my original statement: It's great that you have such an interesting system to implement...but ....

What are you having problems with?

Have you chosen a programming language to implement the system that is going to test your algorithm?

Have you even chosen what platform your going to be developing on (Windows, Linux, Other?)

Have you looked at xmethods to see if it could help to populate your repository?

[buvanaa]

Hhamid63,
how did u proceed ur work. i have the same problem. if u had found the way please inform me. it will be useful for my research