Understanding object-oriented source code from the behavioural perspective

Comprehension is a key activity that underpins a variety of software maintenance and engineering tasks. The task of understanding object-oriented systems is hampered by the fact that the code segments that are related to a user-level function tend to be distributed across the system. We introduce a tool-supported code extraction technique that addresses this issue. Given a minimal amount of information about a behavioural element of the system that is of interest (such as a use-case), it extracts a trail of the methods (and method invocations) through the system that are needed in order to achieve an understanding of the implementation of the element of interest. We demonstrate the feasibility of our approach by implementing it as part of a code extraction tool, presenting a case study and evaluating the approach and tool against a set of established criteria for program comprehension tools

Quality-aware model-driven service engineering

Service engineering and service-oriented architecture as an integration and platform technology is a recent approach to software systems integration. Quality aspects ranging from interoperability to maintainability to performance are of central importance for the integration of heterogeneous, distributed service-based systems. Architecture models can substantially influence quality attributes of the implemented software systems. Besides the benefits of explicit architectures on maintainability and reuse, architectural constraints such as styles, reference architectures and architectural patterns can influence observable software properties such as performance. Empirical performance evaluation is a process of measuring and evaluating the performance of implemented software. We present an approach for addressing the quality of services and service-based systems at the model-level in the context of model-driven service engineering. The focus on architecture-level models is a consequence of the black-box character of services

The use of Petri nets for modeling pipelined processors

This paper discusses the use of Petri Nets for modeling and analyzing pipelined processors. Petri Nets are particularly well-suited to modeling the synchronization, buffering, resource contention and delicate timing so common in pipelined processors. Tools for simulating, animating and analyzing the behavior of the models are described. The usefulness of the tools and the analysis methods they support in evaluating the performance and analyzing the detailed timing of pipelined microprocessors is illustrated through an example

Synthesizing framework uses from program behavior data

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 42-43).This thesis presents MATCHMAKER, a new synthesis tool that aims to help programmers use software frameworks by synthesizing source code needed to interact with the framework. Software engineers of today are constantly faced with the task of using or extending large software code bases. This proves to be a challenging endeavor, as object-oriented frameworks tend to grow exceedingly intricate. Functionality is spread out among numerous classes and tailoring it for a specific need requires knowledge of exact components to extend and combine. MATCHMAKER is presented to help programmers understand such complex behavior, especially, to help deal with one common task in using frameworks: connecting two classes so that they can interact with each other. Taking as input two classes that the programmer want to connect, MATCHMAKER observes many real runs of the framework, aggregates relevant execution traces in which similar connections are built by client-framework interactions, and synthesizes the necessary source code the user needs to write to make the connection possible. MATCHMAKER relies on the hypothesis that the logical connection between two objects is fulfilled by a chain of pointer references linking them together, and the earliest possible pointer reference chain (called Critical Chain) is critical to the logical connection. MATCHMAKER employs a new program behavior data engine (called DELIGHT) to find the critical chain, uses a special slicing algorithm to dig out the relevant instructions which form the client-framework protocol from the critical chain, and synthesize the client code from the slices. In this thesis we also demonstrate MATCHMAKER's capability on a range of programming tasks using complex software frameworks such as Eclipse, and evaluate MATCHMAKER's usability and its improvement to programming efficiency by comprehensive user study.by Zhilei Xu.S.M

Managing Uncertainty: A Case for Probabilistic Grid Scheduling

The Grid technology is evolving into a global, service-orientated architecture, a universal platform for delivering future high demand computational services. Strong adoption of the Grid and the utility computing concept is leading to an increasing number of Grid installations running a wide range of applications of different size and complexity. In this paper we address the problem of elivering deadline/economy based scheduling in a heterogeneous application environment using statistical properties of job historical executions and its associated meta-data. This approach is motivated by a study of six-month computational load generated by Grid applications in a multi-purpose Grid cluster serving a community of twenty e-Science projects. The observed job statistics, resource utilisation and user behaviour is discussed in the context of management approaches and models most suitable for supporting a probabilistic and autonomous scheduling architecture