Supporting Networked Software Development

Vliet, J.C. [Promotor]Lago, P. [Copromotor

Four-Dimensional Sustainable E-Services

E-services are not sustainable, unless we specifically design for sustainability along four dimensions (4D): economical, technical, environmental, and social. Economic sustainability to ensure that e-services create economic value; technical sustainability so that their technical assets actually enable the e-services to cope with changes; environmental sustainability to avoid that e-services harm the environment they operate in, and social sustainability to ensure e-services provide fair exchange of information between parties. Designing 4D-sustainable e-services is very complex. So far, service-engineering research has left dealing with such complexity unassisted—mainly due to the many initial technical challenges that needed to be overcome. Our goal is to fill this gap, by modeling the fundamentals of 4D-sustainable e-services. We propose a conceptual approach for representing 4D-sustainability. Our goal is to enhance the shared understanding amongst sustainability stakeholders, and to ease sustainability assessment and negotiation. Our approach offers a number of interrelated core elements (common among the four sustainability dimensions) as well as dimension-specific elements, variable elements. By focusing on 4D core elements, we enable describing the essence of sustainable e-services in a unified manner. We illustrate the value of the conceptual model using a real-life case study featuring an airport baggage handling syste

Social Debt in Software Engineering: Insights from Industry

Social debt is analogous to technical debt in many ways: it represents the state of software development organisations as the result of “accumulated” decisions. In the case of social debt, decisions are about people and their interactions. Our objective was to study the causality around social debt in practice. In so doing, we conducted exploratory qualitative research in a large software company. We found many forces together causing social debt; we represented them in a framework, and captured anti-patterns that led to the debt in the first place. Finally, we elicited best practices that technicians adopted to pay back some of the accumulated debt. We learned that social debt is strongly correlated with technical debt and both forces should be reckoned with together during the software process

Resource allocation and feedback in wireless multiuser networks

This thesis focuses on the design of algorithms for resource allocation and feedback in wireless multiuser and heterogeneous networks. In particular, three key design challenges expected to have a major impact on future wireless networks are considered: cross-layer scheduling; structured quantization codebook design for MU-MIMO networks with limited feedback; and resource allocation to provide physical layer security. The first design challenge is cross-layer scheduling, where policies are proposed for two network architectures: user scheduling in single-cell multiuser networks aided by a relay; and base station (BS) scheduling in CoMP. These scheduling policies are then analyzed to guarantee satisfaction of three performance metrics: SEP; packet delay; and packet loss probability (PLP) due to buffer overflow. The concept of the τ-achievable PLP region is also introduced to explicitly describe the tradeoff in PLP between different users. The second design challenge is structured quantization codebook design in wireless networks with limited feedback, for both MU-MIMO and CoMP. In the MU-MIMO network, two codebook constructions are proposed, which are based on structured transformations of a base codebook. In the CoMP network, a low-complexity construction is proposed to solve the problem of variable codebook dimensions due to changes in the number of coordinated BSs. The proposed construction is shown to have comparable performance with the standard approach based on a random search, while only requiring linear instead of exponential complexity. The final design challenge is resource allocation for physical layer security in MU-MIMO. To guarantee physical layer security, the achievable secrecy sum-rate is explicitly derived for the regularized channel inversion (RCI) precoder. To improve performance, power allocation and precoder design are jointly optimized using a new algorithm based on convex optimization techniques

A UML Profile for the Design, Quality Assessment and Deployment of Data-intensive Applications

Big Data or Data-Intensive applications (DIAs) seek to mine, manipulate, extract or otherwise exploit the potential intelligence hidden behind Big Data. However, several practitioner surveys remark that DIAs potential is still untapped because of very difficult and costly design, quality assessment and continuous refinement. To address the above shortcoming, we propose the use of a UML domain-specific modeling language or profile specifically tailored to support the design, assessment and continuous deployment of DIAs. This article illustrates our DIA-specific profile and outlines its usage in the context of DIA performance engineering and deployment. For DIA performance engineering, we rely on the Apache Hadoop technology, while for DIA deployment, we leverage the TOSCA language. We conclude that the proposed profile offers a powerful language for data-intensive software and systems modeling, quality evaluation and automated deployment of DIAs on private or public clouds