Understanding the implementation of a certain feature of a system requires to identify the computational units of the system that contribute to this feature. In many cases, the mapping of features to the source code is poorly documented. In this paper, we present a semi-automatic technique that reconstructs the mapping for features that are triggered by the user and exhibit an observable behavior. The mapping is in general not injective; that is, a computational unit may contribute to several features. Our technique allows to distinguish between general and specific computational units with respect to a given set of features. For a set of features, it also identifies jointly and distinctly required computational units.

Aspect-oriented programming (AOP) controls tangling of concerns by isolating aspects that cross-cut each other into building blocks. Component-based programming (CBP) supports software development by isolating reusable building blocks that can be assembled and connected in many different ways. We show how AOP and CBP can be integrated by introducing a new component construct for programming class collaborations, called aspectual component. Aspectual components extend adaptive plug-and-play components (AP&P) with a modification interface that turns them into an effective tool for AOP. A key ingredient of aspectual components is that they are written in terms of a generic data model, called a participant graph, which is later mapped into a data model. We introduce a new property of this map, called instance-refinement, to ensure the proper deployment of components. We show how aspectual components can be implemented in Java, and demonstrate that aspectual components improve the AspectJ language for AOP from Xerox PARC.

Dynamic information collected as a software system executes can help software engineers perform some tasks on a system more effectively. To interpret the sizable amount of data generated from a system's execution, engineers require tool support. We have developed an off-line, flexible approach for visualizing the operation of an object-oriented system at the architectural level. This approach complements and extends existing profiling and visualization approaches available to engineers attempting to utilize dynamic information. In this paper, we describe the technique and discuss preliminary qualitative studies into its usefulness and usability. These studies were undertaken in the context of performance tuning tasks. Keywords Software visualization, programming environments, software structure, program comprehension, execution trace, performance. 1 INTRODUCTION Effective performance of many software engineering tasks requires knowledge of how the system works. Gaining the desired k...

This paper introduces declarative event patterns (DEPs) as a means to implement protocols while improving their traceability, comprehensibility, and maintainability. DEPs are descriptions of sequences of events in the execution of a system that include the ability to recognize properly nested event structures. DEPs allow a developer to describe a protocol at a high-level, without the need to express extraneous details. A developer can indicate that specific actions be taken when a given pattern occurs. DEPs are automatically translated into the appropriate instrumentation and automaton for recognizing a given pattern. Support for DEPs has been implemented in a proof-of-concept extension to the AspectJ language that is based on advanced compiler technology. A case study is described that compares the use of DEPs in the implementation of a protocol (FTP user authentication) to the use of a set of other approaches, both object-oriented and aspect-oriented.

Modeling object-oriented applications using collaborations and roles is now well accepted. Collaboration-based or role-based designs decompose an application into tasks performed by a subset of the applications' classes. Collaborations provide a larger unit of understanding and reuse than classes, and are an important aid in the maintenance and evolution of the software. This kind of design information is lost, however, at the implementation level, making it hard to maintain and evolve an existing software application. The extraction of collaborations from code is therefore an important issue in design recovery. In this paper we propose an iterative approach which uses dynamic information to support the recovery and understanding of collaborations. We describe a tool we have developed to support our approach and demonstrate its use on a case study.

To fully understand the underlying architecture of an object-oriented software system, both static and dynamic analyses are needed. Dynamic reverse engineering techniques are especially important for understanding the run-time behavior of objects in a distributed object systems and in systems that rely heavily on polymorphism. Shimba, a prototype reverse engineering environment, has been built to support understanding an existing Java software system. The dynamic event trace information is generated automatically as a result of running the target system under a customized sdk [14] debugger and viewed as scenario diagrams using the SCED tool [5]. In SCED, state diagrams can be synthesized automatically from scenario diagrams. This facility is used to visualize the total behavior of a selected object or method, disconnected from the rest of the system. This paper demonstrates how Shimba aids understanding the behavior of Java programs. A case study in made to validate the usefulness of ...

execution frequency

ManyJava programmers believe they do not havetoworry about memory management because of automatic garbage collection. In fact, manyJava programs run out of memory unexpectedly after performing a number of operations. A memory leak in Java is caused when an object that is no longer needed cannot be reclaimed because another object is still referring to it. Memory leaks can be di#cult to solve, since the complexity of most programs prevents us from manually verifying the validityofevery reference.

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Understanding the run-time behavior of object-oriented legacy systems is a complex task due to factors such as late binding and polymorphism. Current approaches extract and use information from the complete execution trace of a system. The sheer size and complexity of such traces make their handling, storage, and analysis difficult. Current software systems which run almost non-stop do not permit such a full analysis. In this paper we present a lightweight approach based on the extraction of a condensed amount of information, e.g., measurements, that does not require a full trace. Using this condensed information, we propose a visualization approach which allows us to identify and understand certain aspects of the objects' lifetime such as their role played in the creation of other objects and the communication architecture they support.