Matjaž B. Jurič

Analysis of the limitations of multiple client handling in a Java server environment

A server infrastructure in web servers, message servers and other parallel systems use a variation of two software architectures for providing concurrency: threaded or event-driven. This paper analyzes the performance limitations of concurrent applications implemented in Java. Both architectures have been evaluated and compared with various design patterns, which combine the best practices from both architectures. For each architecture the suitability for handling a large volume of client requests, the efficient management of a server load, the influence of client request structures, and the physical size of a client request, have been studied. The discussed Java APIs are core technologies for high-level APIs, used in developing web and distributed applications. The research also includes performance comparison on various platforms and discusses performance variation on various versions of a Java runtime. The paper contributes to the understanding of Java-based server architecture capabilities. Core server software architectures and required Java libraries are compared, the reasons for the limitations are identified and guidelines for choosing proper combinations are given.

Improving the reliability of medical software by predicting the dangerous software modules

Software reliability analysis is inevitable for modern medical systems, since a large amount of medical system functionality is now dependent on software, and software does contribute to system failures. Most software reliability models are based on software failure data collected from the project. This creates a problem for the designers since, during the early stage, software failure data are not available. However, a valuable knowledge can be learned from the analysis of previous projects and applied to the new ones. This paper presents the approach that predicts the potentially dangerous software modules under development based on the analysis of the already finished modules using the machine-learning techniques. On the basis of the prediction given by our method software designers are able to devote more testing effort to the dangerous parts of the system, which results in a more reliable medical software system.

Databases for New Age

New generation of databases is presented in the article. Advantages encountered using object database during all phases of software development cycles are presented. It is shown that full exploitation of object technology is possible by use of object databases. Based on our experiences with object oriented tools and object databases, discussion about possibilities of using only one consistent conceptual model across all phases of development process is presented. The impact of object databases on software process improvement is indicated.

Why Many Interfaces Are Needed for a Distributed Object

Distributed object technology is one of the most important technologies for new generation of information systems. In the article the basic ideas of distributed objects are described and the two most important distributed object models are compared. The advantages and disadvantages obtained from the pilot projects are described. The inability of objects to support multiple views (interfaces) are discussed and the ideas which allow objects to get and hide behavior without recreation are described. The ability to apply these ideas using available tools are shown.

Integration of strategic, tactical and technical OO measurement

For measurement to become cost effective and efficient it should be directed by business goals. Since our goal when introducing object technology is to build better software it is necessary to perform technical OO measurement and relate it not only to tactical but also to strategic goals. In the paper we present some concepts of an environment that might help us to integrate and provide compliance between different aspects of OO measurement.