Ivan Benc

Service development and application integration with public information system mediator

The software development industry is facing two important issues: enabling rapid service development and integration of existing applications. Current approaches result in custom solutions that are not generally applicable. Therefore, we propose a service development and application integration system acting as a mediator between developers, users, services, and applications. In this paper, we present the prototype of the public information system mediator MidArc. We describe the mediators system architecture, the technology it is built upon, and the process of integration of distributed applications. The mediator prototype was created and used to develop the formal automata simulator as a public service, to integrate the automata simulator service into the distance learning application, and to run the distance learning system.

Decision function in hybrid self-adaptive WWW cache coherence protocol (hSATTL)

To improve the performance of the multiprocessor, distributed and Internet-based systems, data replication is being introduced. Existence of multiple copies of the same object in the system causes the cache coherence problem. There are two basic mechanisms for maintaining cache coherence: write-invalidate and write-update mechanisms. Various protocols for multiprocessor and distributed systems have been developed that use both coherence mechanisms in order to maintain cache coherence with minimal overhead costs. These protocols are based on a decision function that dynamically switches between write-update and write-invalidate mechanisms. As a part of the hSATTL cache coherence protocol we designed a new decision function adapted for Internet-based systems that dynamically switches between basic coherence mechanisms. In order to prove the efficiency of the designed decision function we compared the performance of the hSATTL protocol with the performance of the ATTL and SATTL protocols, which do not implement decision functions. As the performance measure, we use the server load and the amount of data that is transferred between the server and the proxy in order to maintain cache coherence.

Building Distributed Access Control System Using Service-Oriented Programming Model

Service-oriented programming model is a new methodology for building service-oriented applications. In the service-oriented programming model, an application is assembled from loosely coupled, dynamically bounded services that mutually cooperate and compete in order to achieve the application s goal. In this paper, we present our experiences with the service-oriented programming model attained through development and testing of access control system. The access control system is a service-oriented application that manages security in the virtual organizations. We indicate how service-oriented programming model facilitates run-time reconfiguration of the access control system. Further, we evaluate and compare the performance of several architectures of the access control system with different levels of parallelism and concurrency