Recent advances in hardware development coupled with the rapid adoption and broad applicability of cloud computing have introduced widespread heterogeneity in data centers, significantly complicating the management of cloud applications and data center resources. This paper presents the CACTOS approach to cloud infrastructure automation and optimization, which addresses heterogeneity through a combination of in-depth analysis of application behavior with insights from commercial cloud providers. The aim of the approach is threefold: to model applications and data center resources, to simulate applications and resources for planning and operation, and to optimize application deployment and resource use in an autonomic manner. The approach is based on case studies from the areas of business analytics, enterprise applications, and scientific computing.

To cope with project constraints, copying and customizing existing software products is a typical practice to flexibly serve customer-specific needs. In the long term, this practice becomes a limitation for growth due to redundant maintenance efforts or wasted synergy and cross selling potentials. To mitigate this limitation, customized copies need to be consolidated into a single, variable code base of a software product line (SPL). However, consolidation is tedious as one must identify and correlate differences between the copies to design future variability. For one, existing consolidation approaches lack support of the implementation level. In addition, approaches in the fields of difference analysis and feature detection are not sufficiently integrated for finding relationships between code modifications. In this paper, we present remedy to this problem by integrating a difference analysis with a program dependency analysis based on Program Dependency Graphs (PDG) to reduce the effort of consolidating developers when identifying dependent differences and deriving clusters to consider in their variability design. We successfully evaluated our approach on variants of the open source ArgoUML modeling tool, reducing the manual review effort about 72% with a precision of 99% and a recall of 80%. We further proved its industrial applicability in a case study on a commercial relationship management application.

Economically sustainable software systems must be able to cost-effectively evolve in response to changes in their environment, their usage profile, and business demands. However, in many software development projects, sustainability is treated as an afterthought, as developers are driven by time-to-market pressure and are often not educated to apply sustainability-improving techniques. While software engineering research and practice has suggested a large amount of such techniques, a holistic overview is missing and the effectiveness of individual techniques is often not sufficiently validated. On this behalf we created a catalog of “software sustainability guidelines” to support project managers, software architects, and developers during system design, development, operation, and maintenance. This paper describes how we derived these guidelines and how we applied selected techniques from them in two industrial case studies. We report several lessons learned about sustainable software development.

Systematic decision support for architectural design decisions is a major concern for software architects of evolving service-oriented systems. In practice, architects often analyse the expected performance and reliability of design alternatives based on prototypes or former experience. Model-driven prediction methods claim to uncover the tradeoffs between different alternatives quantitatively while being more cost-effective and less error-prone. However, they often suffer from weak tool support and focus on single quality attributes. Furthermore, there is limited evidence on their effectiveness based on documented industrial case studies. Thus, we have applied a novel, model-driven prediction method called Q-ImPrESS on a large-scale process control system consisting of several million lines of code from the automation domain to evaluate its evolution scenarios. This paper reports our experiences with the method and lessons learned. Benefits of Q-ImPrESS are the good architectural decision support and comprehensive tool framework, while one drawback is the time-consuming data collection.

In component-based software engineering, existing components are often reused in new applications. Correspondingly, the response time of an entire component-based application can be predicted from the execution durations of individual component services. These execution durations depend on the runtime behavior of a component which itself is influenced by three factors: the execution platform, the usage profile, and the component wiring. To cover all relevant combinations of these influencing factors, conventional prediction of response times requires repeated deployment and measurements of component services for all such combinations, incurring a substantial effort. This paper presents a novel comprehensive approach for reverse engineering and performance prediction of components. In it, genetic programming is utilized for reconstructing a behavior model from monitoring data, runtime bytecode counts, and static bytecode analysis. The resulting behavior model is parameterized over all three performance-influencing factors, which are specified separately. This results in significantly fewer measurements: The behavior model is reconstructed only once per component service, and one application-independent bytecode benchmark run is sufficient to characterize an execution platform. To predict the execution durations for a concrete platform, our approach combines the behavior model with platform-specific benchmarking results. We validate our approach by predicting the performance of a file sharing application.