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The population density in urban areas is rapidly rising, leading to a constant need for new infrastructure and services for citizens. To reduce the time to implementation and optimise the monetary cost of various solutions, the plans and policies of local authorities and stakeholders would benefit from undergoing a series of virtual stress tests. To this end, prescriptive and predictive technologies are widely adopted to optimise city planning and to understand the urban processes and environment such as air pollution and transportation. Nevertheless, holistic sandboxes tightly integrated with cities are still largely lacking. The city digital twin is a promising concept that provides a tool for exploration of new solutions in a controlled environment before their deployment. The digital twin is a virtual replica of the real city, which collects data from the infrastructure, processes and services using not only the available systems, but also purposely built connected devices and sensors. In this context, the establishment of urban living labs facilitates the monitoring and understanding of urban processes and enriches the digital twin with highly-relevant data. This paper presents an urban living lab, under deployment in the district of Lozenets in Sofia, Bulgaria. It is part of a larger initiative for developing a city digital twin of Sofia to support the design, exploration, and experimentation of different solutions. The living lab is equipped with sensors for monitoring air quality, atmospheric parameters, noise pollution and pedestrian flows. In addition, a Light Detection and Ranging (LiDAR) system is realised as an edge computing facility at one of the busiest intersections of the district. Along with the equipment, the paper describes the architecture and components of the platform for data collection, storage, processing, and visualization. Finally, high-priority studies are presented, and their demographic and economic impact is discussed.

Component-based software engineering and software architecture are tightly connected areas in computer science. Software architecture presents the functionality of the system as decomposition into components, the properties of these components and the connectors between them. This paper illustrates a methodology for application of the theory of Generalized Nets (GNs) as a language for description of software systems architecture. According to this methodology, every component in the system, as well as every connector is represented by a single GN transition. This way the positions of the transition describe the ports of components and connectors in the system. This paper introduces a model of the component-based architecture of the e-learning system ARCADE, which is created, with respect to the proposed methodology for description with GNs. The four main subsystems are regarded as components in the GNs model. Their additional sub-modules are presented as the services provided by the components. Method calls are regarded as the connectors between these components. Further, the GNs model is compared with the existing UML diagrams, specifying the design of ARCADE., The paper has been presented at the International Conference Pioneers of Bulgarian Mathematics, Dedicated to Nikola Obreshko ff and Lubomir Tschakaloff , Sofi a, July, 2006.

The work reported in this paper was supported by a research project funded by the National Scientific Fund, Bulgarian Ministry of Education, Youth and Science, via agreement no. DOO2-182., Software applications created on top of the service-oriented architecture (SOA) are increasingly popular but testing them remains a challenge. In this paper a framework named TASSA for testing the functional and non-functional behaviour of service-based applications is presented. The paper focuses on the concept of design time testing, the corresponding testing approach and architectural integration of the consisting TASSA tools. The individual TASSA tools with sample validation scenarios were already presented with a general view of their relation. This paper’s contribution is the structured testing approach, based on the integral use of the tools and their architectural integration. The framework is based on SOA principles and is composable depending on user requirements.

Agile methodologies for software development meet the challenges of the current highly dynamic and competitive business environment. The aim of this case study is to improve existing software development process in a project for the public administration, following the basic principles of agile methodologies. Appropriate metrics for continuous evaluation of the process are introduces to help evaluating and improving the methodology. The main objectives of the new methodology are to improve communication with customers, to improve communication among different distributed teams and inside the teams, and to continuously evaluate the way software is developed through selection and usage of software metrics. The paper presents the results of methodology adoption in two subsequent iterations of a real project.

In the last few years Agile methodologies appeared as a reaction to traditional ways of developing software and acknowledge the need for an alternative to documentation driven, heavyweight software development processes. This paper shortly presents a combination between Rational Uni ed Process and an agile approach for software development of e-business applications. The resulting approach is described stressing on the strong aspects of both combined methodologies. The article provides a case study of the proposed methodology which was developed and executed in a successful e-project in the area of the embedded systems.

Like all other New Member States (NMS) Bulgaria is experiencing a dramatic change in all areas of its society. These changes reflect very seriously on the research capacity of the country and, in particular to Sofia University (SU). The Faculty of Mathematics and Informatics (FMI) has experienced some serious problems closely related to the general socio-economic and the research environment in Bulgaria. This paper describes a model for strengthening the research capacity of FMI, especially the one in the area of Software Engineering. The case study of successful industry-university cooperation in the framework of European project is presented

Despite the tendency of growing the size and complexity of the developed software, significant part of it is still developed by autonomous developers. The current research study proposes a modification of PSP which aims at lightening the software development process and making it easier to follow, while keeping the PSP basic principles. The new methodology is extended with proven efficient development practices from the Extreme Programming in order to support better project planning and product quality control. The paper presents the results of methodology adoption and compares it to ad-hock development.

Nowadays, with steadily increasing number of various markup languages and their dialects, application developers need more often to rewrite the presentation in order to support more client devices. Java programmers using JSP for dynamic generation of the presentation layer have to create for given content different Java Server Pages (JSP)´s for showing it in different HTTP, WAP and Palm client. Instead of rewriting the same JSP several times, authors demonstrate an approach of separation of content and presentation form, by means of XSLT transformation over XML content. The client device type is detected by a server-side detector, which uses the type for choosing the correct XSLT for the correspondent XML content generated by a JSP. Moreover, for non-XML browsers, the detector invokes a transformer, which generates on-the-fly any-ML presentation using both the XML and XSLT.

Service-oriented architecture (SOA) is the latest attempt to better link the business with technology. Testing a SOA applications become more and more complex, as it should be continuous, not just in development and integration, but in deployment, because an SOA by nature is never a static application. Even if each service in a SOA application is tested thoroughly and carefully the quality of the final application may suffer because testing is not enough after the integration of the services. This article presents the challenges and problems that test teams experience when testing SOA applications. It also summarizes how the testing of SOA is carried out now and gives some ideas on further improvements.

The paper introduces a light method for software development applicable to small teams developing projects characterised with often changing requirements, tight schedules, and high quality demands. The method is called eXPERT and builds on the principles of eXtreme Programming (XP) and the Personal Software Process (PSP). The paper describes the objectives and logics of the eXPERT approach, as well as framework for analyzing experiments with it.

All Small and Medium Enterprises (SMEs) developing e-commerce and e-business software have similar business objectives as less time to the market, better quality, and cheaper cost. Current projects are very large and complex and it becomes difficult to handle them. There are different private methods and techniques developed to overcome this problem. The latest studies on the well-known software development methodologies and their applicability to e-projects reveal that they do not fit very well the priorities, the abilities and the corporate culture of SMEs developing e-business or e-commerce applications. Traditional methodologies assume that if the programmers tried hard enough, they could anticipate the complete set of requirements early and reduce cost by eliminating change, which can be reasonable in stable environments, but it is not the case at all in e-projects. In the fast changing environment of e-projects change cannot be eliminated; rather than eliminate rework, the new strategy is to reduce its cost, while retaining quality. There are a number of reports showing increased productivity and software quality by applying Extreme Programming (XP) principles [1]. However, even projects that have adopted several or all XP practices meet project management problems, which are related to estimating and planning the project, both in terms of time and costs. To overcome this obstacle European project eXPERT (IST-2001-34488) has the objective to define agile and integrated approach guiding development of e-projects. The approach, named also eXPERT, focuses on combining XP and Personal Software Process (PSP) practices [2]. The main aims and logics of eXPERT project and underlying software methodologies are presented in this paper. The paper is organized as follows: Section 2 presents the objectives of eXPERT project. In section 3 we describe the basic software engineering practices, which will be used – XP and PSP. Section 4 discusses issues in the process of combination of XP and PSP principles. Section 5 concludes the paper.