Mehran Najafi

Research Problem

In a cloud environment, software is provided by web services. Traditional web services (called Data Services) process client's datacompletely at the server-side. Consequently, the service client need sto reveal its sensitive data and hence its privacy and security couldbe violated. Moreover, large volume client data is processed remotely, increasing network traffic.

Client-side Task Services

I propose an extension to the SOA infrastructure model by adding a new component, called the Service Representative (SR), and introducing a new type of web services, called Task Services. A task service is a web service where some of its required parameters are processed locally at the client-side by the service representative.

WS-Competition

I propose a novel service selection approach that compares alternative services based on their performance in a specific client context. For this purpose, the SOA model is extended through a component named the Competition Desk, that holds a competition among alternative services taken from the service client.

Client-side Service Composition

Traditionally, composition of web services is performed at the server-side. This requires transferring client data among collaborating web services, which may cause data privacy violation, security breaches, or network traffic overloading. The proposed task services and service representative allow us to presenet a new concept called client-side service composition, where collaborating web services employ the service representative to provide a composite task service at the client side.

Service Composition Certifier

I propose to add a new component named the Service Composition Certifier (SCC), to the SOA model to certify client-defined service composition modles including server-side data services and client-side task services. The certification process includes two phases: firstly, the SCC verifies the composition model to check wether the collaborating services are compatible. Secondly, the SCC validates the composition model based on a policy submitted by the client to check wether this model meets the client's expectations. For this purposes, I utilized formal methods including a process algebra as well as a temporal logic.