Ivan Rozman

Decision Trees: An Overview and Their Use in Medicine

In medical decision making (classification, diagnosing, etc.) there are many situations where decision must be made effectively and reliably. Conceptual simple decision making models with the possibility of automatic learning are the most appropriate for performing such tasks. Decision trees are a reliable and effective decision making technique that provide high classification accuracy with a simple representation of gathered knowledge and they have been used in different areas of medical decision making. In the paper we present the basic characteristics of decision trees and the successful alternatives to the traditional induction approach with the emphasis on existing and possible future applications in medicine.

Comparison of performance of Web services, WS-Security, RMI, and RMI-SSL

This article analyses two most commonly used distributed models in Java: Web services and RMI (Remote Method Invocation). The paper focuses on regular (unsecured) as well as on secured variants, WS-Security and RMI-SSL. The most important functional differences are identified and the performance on two operating systems (Windows and Linux) is compared. Sources of performance differences related to the architecture and implementation are identified. The overheads related to the usage of security and the influences of JCE (Java Cryptography Extension) security providers on the performance of secured remote invocations are identified. Finally, the impact of distributed models on design and implementation of distributed applications is identified and guidelines for improving distributed application performance in design and implementation stage are provided. The paper contributes to the understanding of functional and performance related differences between Web services and RMI and their secure variants, WS-Security and RMI-SSL.

WSDL and UDDI extensions for version support in web services

Versioning is an important aspect of web service development, which has not been adequately addressed so far. In this article, we propose extensions to WSDL and UDDI to support versioning of web service interfaces at development-time and run-time. We address service-level and operation-level versioning, service endpoint mapping, and version sequencing. We also propose annotation extensions for developing versioned web services in Java. We have tested the proposed solution for versioning in two real-world environments and identified considerable improvements in service development and maintenance efficiency, improved service reuse, and simplified governance.

Managing the complexity of SPI in small companies

Most known models for SPI (e.g. SEI CMM, ISO standards and other methods derived from those mentioned) are primarily suited for large or medium organizations, but with some tailoring they provide substantial support also for the SPI in small organizations considering their specific characteristics. In the article a case of such tailoring – the PROCESSUS model – is presented. The baseline of the methodology is the integration of the CMM and the ISO 9001 together with the ISO 9000-3. According to the integrated model and the study of different lifecycles, a set of standard procedures (SP) and standard documents (SD) was defined. Each standard procedure provides guidelines on how to perform related activities, who is involved, which documents are supposed to be used/derived within the procedure etc. The set of SP and SD is the essential help for SPI conduction – for the purpose of small companies the optimal use of suggested documents and the disposition of roles was defined. The SP-SD set is also described in the article. Copyright

An empirical examination of application frameworks success based on technology acceptance model

Framework-based development is currently regarded as one of the most promising software development approaches when it comes to improvements in lead time, productivity and quality. However, many frameworks and projects based on frameworks still report failures, which indicate that there are problems related to both frameworks technology and frameworks usage. The objective of our research was to examine the major drivers that have an impact on a frameworks acceptance and a frameworks success. We used the technology acceptance model (TAM) and Seddons information systems success model as our underlying theory. Data collected from an online survey of 389 active framework users was used to test hypothesized models. Data analysis was performed via structural equation modeling. Our findings support the post-adoption version of TAM and the relationship between continuous use and the successful use of systems, where more use also means more net benefits. We found that the successful use of frameworks is mainly dependent on two factors: continuous framework usage intention and the perceived usefulness of the framework. Several practical and theoretical implications can be foreseen including advances in framework development guidelines and insight into the relationship between the acceptance and success of frameworks.

Object serialization analysis and comparison in Java and .NET

This article compares binary and XML object serialization on Java and Microsoft .NET platforms from the performance and size perspective. It uses three different types of objects and different number of objects to make a comparison which reflects real-world circumstances. The article has the following contributions: (1) it compares binary and XML serialization between Java and .NET to compare the efficiency of both platforms; (2) it compares binary and XML serialization within the platforms to compare the differences between the two serialization types; (3) it studies the reasons for performance differences and provides possible performance optimizations.

Java RMI, RMI tunneling and Web services comparison and performance analysis

This article compares different approaches for developing Java distributed applications which have to communicate through firewalls and proxies, including RMI over open ports, HTTP-to-port, HTTP-to-CGI, HTTP-to-servlet tunneling and web services. A functional comparison of approaches has been done, as well as a detailed performance analysis with overhead analysis and identification of optimizations. Therefore the paper contributes to the overall understanding of different approaches for developing Java distributed applications in circumstances, where the communication through firewalls and/or proxies is inevitable. The paper also contributes to the understanding of performance related issues.

Performance comparison of CORBA and RMI

Abstract Distributed object architectures and Java are important for building modern, scalable, web-enabled applications. This paper is focused on qualitative and quantitative comparison of two distributed object models for use with Java: CORBA and RMI. We compare both models in terms of features, ease of development and performance. We present performance results based on real world scenarios that include single client and multi-client configurations, different data types and data sizes. We evaluate multithreading strategies and analyse code in order to identify the most time-consuming methods. We compare the results and give hints and conclusions. We have found that because of its complexity CORBA is slightly slower than RMI in simple scenarios. On the other hand, CORBA handles multiple simultaneous clients and larger data amounts better and suffers from far lower performance degradation under heavy client load. The article presents a solid basis for making a decision about the underlying distributed object model.

Automated software size estimation based on function points using UML models

A systematic approach to software size estimation is important for accurate project planning. In this paper, we will propose the unified mapping of UML models into function points. The mapping is formally described to enable the automation of the counting procedure. Three estimation levels are defined that correspond to the different abstraction levels of the software system. The level of abstraction influences an estimates accuracy. Our research, based on a small data set, proved that accuracy increases with each subsequent abstraction level. Changes to the FPA complexity tables for transactional functions will also be proposed in order to better quantify the characteristics of object-oriented software.

Knowledge discovery with classification rules in a cardiovascular dataset

In this paper we study an evolutionary machine learning approach to data mining and knowledge discovery based on the induction of classification rules. A method for automatic rules induction called AREX using evolutionary induction of decision trees and automatic programming is introduced. The proposed algorithm is applied to a cardiovascular dataset consisting of different groups of attributes which should possibly reveal the presence of some specific cardiovascular problems in young patients. A case study is presented that shows the use of AREX for the classification of patients and for discovering possible new medical knowledge from the dataset. The defined knowledge discovery loop comprises a medical experts assessment of induced rules to drive the evolution of rule sets towards more appropriate solutions. The final result is the discovery of a possible new medical knowledge in the field of pediatric cardiology.