Semantics-directed implementation of method-call interception

We describe a form of method-call interception (MCI) that allows the programmer to superimpose extra functionality onto method calls at run-time. We provide a reference semantics and a reference implementation for corresponding language constructs. The setup applies to class-based, statically typed, compiled languages such as Java. The semantics of MCI is used to direct a language implementation with a number of valuable properties: simplicity of the implementational model and run-time adaptation capabilities and static type safety and separate compilation and reasonable performance. Our implementational development employs sourcecode instrumentation. We start from a naive implementational model, which is subsequently refined to optimise program execution. The implementation is assessed via benchmarks

Investigating the Relationship Between Aspects and Program Slices

Department of Computer Scienc

Dynamic AOP with PROSE. In:

Abstract. Dynamic Aspect-Oriented Programming (d-AOP) is an important tool to implement adaptation in a wide variety of applications. In particular, large distributed infrastructures, middleware, and pervasive computing environments can greatly benefit from d-AOP to adapt software systems at run time. In this paper, we discuss the design of PROSE, an open source, generic platform for software adaptation. The paper discusses the join-points needed in practical systems together with examples of how they can be used, different implementation strategies and their practical implications. It also describes a highly efficient mechanism to implement stub and advice weaving

Supporting dynamic aspect-oriented features

Aspect-oriented programming techniques extend object-oriented programming with new methods to modularize concerns that otherwise would be non-modular. For example, logging concerns are typically scattered across a system but using aspect-oriented techniques they can be localized into a single high-level module. These techniques typically take modular high-level code and statically transform it into non-modular intermediate code. The contribution of this work is the design and implementation of a flexible and dynamic intermediate-language (IL) model. The main motivation for the design of this IL model is to support a variety of dynamic aspect-oriented language constructs that are proposed in recent literature such as CaeserJ\u27s deploy, history-based pointcuts, and control flow constructs. Our IL model provides a higher level of abstraction compared to traditional object-oriented ILs as a compilation target for such constructs, which makes it easier to provide efficient implementations of these constructs. We demonstrate these benefits by providing an industrial strength implementation for our IL model, by showing translation strategies from dynamic source-level constructs to our improved IL, and by analyzing the performance of the resulting IL code. Our evaluation using the SPEC JVM98 and Java Grande benchmarks shows that the overhead of supporting a dynamic deployment model can be reduced to as little as ~1.5%, when compared to the unmodified VM

Towards a Taxonomy of Software Evolution

Previous taxonomies of software evolution have focused on the purpose of the change rather than the underlying mechanisms. This paper proposes a taxonomy of software evolution based on the characterizing mechanisms of change and the factors that influence these mechanisms. The taxonomy is organized into the following logical groupings: temporal properties, objects of change, system properties, and change support. The ultimate goal of this taxonomy is to provide a framework that positions concrete tools, formalisms and methods within the domain of software evolution. Such a framework would considerably ease comparison between these tools, formalisms and methods. It would also allow practitioners to evaluate their potential use in particular change scenarios. As an initial step towards this taxonomy, the paper presents a framework that can be used to characterize software change support tools and to identify the factors that impact on the use of these tools. The framework is evaluated by applying it to three different change support tools and by comparing these tools based on this analysis

Towards an aspect weaving BPEL engine

This position paper proposes the use of dynamic aspects and the visitor design pattern to obtain a highly configurable and extensible BPEL engine. Using these two techniques, the core of this infrastructural software can be customised to meet new requirements and add features such as debugging, execution monitoring, or changing to another Web Service selection policy. Additionally, it can easily be extended to cope with customer-specific BPEL extensions. We propose the use of dynamic aspects not only on the engine itself but also on the workflow in order to tackle the problems of Web Service hot deployment and hot fixes to long running processes. In this way, composing aWeb Service "on-the-fly" means weaving its choreography interface into the workflow

An Autonomic Cross-Platform Operating Environment for On-Demand Internet Computing

The Internet has evolved into a global and ubiquitous communication medium interconnecting powerful application servers, diverse desktop computers and mobile notebooks. Along with recent developments in computer technology, such as the convergence of computing and communication devices, the way how people use computers and the Internet has changed people´s working habits and has led to new application scenarios. On the one hand, pervasive computing, ubiquitous computing and nomadic computing become more and more important since different computing devices like PDAs and notebooks may be used concurrently and alternately, e.g. while the user is on the move. On the other hand, the ubiquitous availability and pervasive interconnection of computing systems have fostered various trends towards the dynamic utilization and spontaneous collaboration of available remote computing resources, which are addressed by approaches like utility computing, grid computing, cloud computing and public computing. From a general point of view, the common objective of this development is the use of Internet applications on demand, i.e. applications that are not installed in advance by a platform administrator but are dynamically deployed and run as they are requested by the application user. The heterogeneous and unmanaged nature of the Internet represents a major challenge for the on demand use of custom Internet applications across heterogeneous hardware platforms, operating systems and network environments. Promising remedies are autonomic computing systems that are supposed to maintain themselves without particular user or application intervention. In this thesis, an Autonomic Cross-Platform Operating Environment (ACOE) is presented that supports On Demand Internet Computing (ODIC), such as dynamic application composition and ad hoc execution migration. The approach is based on an integration middleware called crossware that does not replace existing middleware but operates as a self-managing mediator between diverse application requirements and heterogeneous platform configurations. A Java implementation of the Crossware Development Kit (XDK) is presented, followed by the description of the On Demand Internet Computing System (ODIX). The feasibility of the approach is shown by the implementation of an Internet Application Workbench, an Internet Application Factory and an Internet Peer Federation. They illustrate the use of ODIX to support local, remote and distributed ODIC, respectively. Finally, the suitability of the approach is discussed with respect to the support of ODIC

Programmiersprachen und Rechenkonzepte

Seit 1984 veranstaltet die GI--Fachgruppe 2.1.4 "Programmiersprachen und Rechenkonzepte", die aus den ehemaligen Fachgruppen 2.1.3 "Implementierung von Programmiersprachen" und 2.1.4 "Alternative Konzepte für Sprachen und Rechner" hervorgegangen ist, regelmäßi g im Frühjahr einen Workshop im Physikzentrum Bad Honnef. Das Treffen dient in erster Linie dem gegenseitigen Kennenlernen, dem Erfahrungsaustausch, der Diskussion und der Vertiefung gegenseitiger Kontakte