Herwig Mannaert

Should You Adopt Open Source Software

Many organizations use open source infrastructure software such as Linux, and open source software (OSS) is generally considered a viable technology. Both professional and academic literature devote much attention to the OSS phenomenon. However, decision makers considering the adoption of OSS face a plethora of books, research papers, and articles highlighting OSSs advantages and disadvantages. Different articles attach different levels of importance to these advantages or factors related to the adoption decision. Reasons for adopting OSS vary from the pragmatic. Organizations must consider the advantages and disadvantages of open source software before adopting it.

Challenges and strategies in the use of Open Source Software by Independent Software Vendors

Open Source Software (OSS) has already been adopted by a large number of organizations. An important - but sometimes neglected - group of OSS users are Independent Software Vendors (ISVs). ISVs often develop their applications on top of OSS platform software. Frequently, this requires making several extensions and modifications to these OSS components. We identify a number of challenges that ISVs face in handling these extensions and modifications. Next, we describe several strategies ISVs can follow in maintaining these modifications. Finally, we suggest an opportunity for a closer collaboration between OSS projects and ISVs which could be mutually beneficial.

Towards evolvable software architectures based on systems theoretic stability

In todays increasingly volatile environments, evolvability is quickly becoming the most desirable characteristic of information systems. Current information systems still struggle to provide these high levels of evolvability. Based on the concept of stability from systems theory, we require that information systems should be stable with respect to a set of anticipated changes in order to exhibit high evolvability. This requires that information systems should be free from so‐called combinatorial effects. Combinatorial effects occur when the impact of a change is dependent on the size of the information system. To eliminate these combinatorial effects, we propose four theorems that are constraints on the modular structure of software architectures. The theorems are prescriptive and ensure that stable information systems are built, thereby guaranteeing high evolvability. We further present five higher level modular structures called elements. These elements provide the core functionality of information systems and comply fully with the stringent constraints implied by the four theorems. The internal structure of these elements is described by design patterns which are eligible for automatic code generation. These design patterns offer a constructive proof that it is possible to build information systems in practice by applying this set of theorems. Copyright

The transformation of requirements into software primitives: Studying evolvability based on systems theoretic stability

Evolvability is widely considered to be a crucial characteristic of software architectures, particularly in the area of information systems. Although many approaches have been proposed for improving evolvability, most indications are that it remains challenging to deliver the required levels of evolvability. In this paper, we present a theoretical approach to how the concept of systems theoretic stability can be applied to the evolvability of software architectures of information systems. We define and formalize the transformation of a set of basic functional requirements into a set of instantiations of software constructs. We define this transformation using both a static and a dynamic perspective. In the latter perspective, we formulate the postulate that information systems should be stable against new requirements. Based on this postulate, we derive a number of design theorems for software implementation. Using this transformation we use theoretical arguments to derive that these theorems contribute to achieving stability.

Web services based systems for network management and provisioning: a case study

The monitoring and management of computer and telecommunication networks becomes increasingly difficult as these networks grow in size and complexity. Moreover, several new functional requirements appear for these network management systems in the emerging field of digital multimedia networks. Therefore, the need for scalable and distributed network management systems based on open communication standards remains as relevant as ever. We investigate the use of Web services as an open communication standard for network management systems. After a concise description of Web services and their possible advantages for network management systems, we present a case study. A Web service architecture is used to build a network management system for a data broadcasting network to distribute digital movies. The presented architecture allows several additional management functionalities that are required in such digital content networks.

An OPC UA interface for an evolvable ISA88 control module

Normalized systems theory has recently been proposed to engineer evolvable information systems. This theory includes a potential of improvement in control software for the automation of production systems. This paper aims at contributing towards evolvable and therefore easy-to-maintain control software. We introduce IEC 61131–3 code which complies with the theorems of normalized systems, forming a building block which complies with the model of an ISA88 control module, accessible via an OPC UA interface. Since OPC UA brings control software to a new level, it enables original intra-process projects to interoperate in an inter-process context. OPC UA offers new possibilities for system integration, but might also lead to a larger impact of evolvability problems.

Web portal for multicast delivery management

In this paper, a Web portal is presented for multicast communication management, providing fully automatic service management with integrated provisioning of hardware equipment. The portal is based on an open and configurable object‐oriented framework, that allows self‐provisioning by the user and the seamless integration with all types of multicast application software. As its topological structure is ideally suited for multicasting, and it allows the accurate control of the transmission bandwidth, the portal focuses currently on satellite as a delivery medium. The software architecture, the implementation, and the application usage of the Web portal for multicast delivery are described.

Identifying Combinatorial Effects in Requirements Engineering

There are several best practices and proposals that help to design and develop software systems immune (to some extent) to combinatorial effects as these systems evolve. Normalized Systems theory, considered at the software architecture level, is one of such proposals. However, at the requirements engineering (RE)-level, little research has been done regarding this issue. This paper discusses examples related with this problem considering two distinct RE abstract levels, namely at the business and system levels. The examples provided follow the notations and techniques typical used to model the software system at such levels, namely DEMO/EO, BPMN, and UML (Use Cases and Class diagrams). The analysis of these examples suggests that combinatorial effects can be easily found at these different levels. This paper also proposes a research agenda to further investigate this matter in terms of the effects of combinatorial effects, and envisions the mechanisms and solutions for dealing with them. It is suggested that an artifact-based, domain-specific approach is best suited to achieve highly agile enterprises and RE-processes in the future.

Positioning the normalized systems theory in a design theory framework

Several frameworks have been proposed to define design science and design theory. For this reason, positioning a research stream within both paradigms has become a difficult exercise. In this paper, the Normalized Systems (NS) theory is positioned within design science and design theory, in particular the design theory framework formulated by Gregor & Jones (2007). Normalized Systems theory has been proposed as a way to cope with the ever increasingly agile environment to which organizations and their software applications need to adapt. The results of positioning NS within the presented framework for design theories show that NS almost fully incorporates all components of the design theory anatomy. The application of NS theory to other fields is also discussed. By positioning Normalized System theory within design science and design theory, we also believe to contribute to the definition of both fields in this paper.

The use of open source software platforms by Independent Software Vendors: issues and opportunities

The Cast4All Content Conductor Platform is an integration and provisioning suite to manage data broadcasting networks in general and digital cinema networks in particular. The framework makes extensive use of open source components and contains several extensions and modifications to those components. It is a typical case of an Independent Software Vendor (ISV) building application software on top of open source platform software. In the spirit of the open source movement, the extensions or modifications to the open source components could be contributed back to the community. However, in this paper we discuss several issues that companies face in such a situation. They extend far beyond the obvious decision whether to keep the developed code proprietary, and should not be neglected. It is argued that a closer collaboration between open source projects and independent software vendors would be beneficial to all.