Aspect-oriented modelling and analysis of information systems

In this paper we introduce an approach of aspect-oriented modelling and analysis of information systems. First we give an overview of the concepts of Aspect Oriented Programming and provide an outlook to model aspect-oriented programs. On the basis of this introduction, we describe a method of using aspects at the modelling level and weaving them into a single integrated model. Finally, we extend this framework with the automatic construction of analysis models based on separate aspect models. In our example, fault tolerance structures are modelled by aspects and the analysis model is a dependability model that is used to determine the non-functional properties of the system like reliability and availability. In this way the separate design of the functionality and the dependability is supported and the design decisions concerning fault tolerance can be analysed on the basis of the dependability model

On the design of aspect-oriented composition models for software evolution

Aspect-oriented programming is an emerging approach in software development,\ud which provides new possibilities for separation of concerns. Aspectoriented\ud languages offer abstractions for the implementation of concerns\ud whose modularization cannot be achieved by using traditional programming\ud languages. Such concerns are generally termed as crosscutting concerns. It is\ud generally agreed that separating the right concerns from each other enhances\ud software quality factors such as reusability and adaptability. The separated\ud concerns in software must be composed together so that software behaves\ud according to its requirements in a coherent way. We refer to language mechanisms\ud that separate and compose concerns as 'composition mechanisms'. This\ud thesis evaluates the software composition mechanisms of current aspectoriented\ud languages from the perspective of software quality factors such as\ud evolvability, comprehensibility, predictability and adaptability. Based on this\ud study, the thesis proposes novel extensions to current aspect-oriented\ud languages so that programs written in these languages exhibit better quality.\ud A considerable number of aspect-oriented languages has been introduced for\ud modularizing crosscutting concerns. Naturally, these languages share a number\ud of common concepts and have distinctive features as well. For this reason, we\ud propose a reference model that aims to capture the common and distinctive\ud concepts of aspect-oriented languages. This reference model provides a basis\ud to understand the important characteristics of the state-of-the-art AOP\ud languages and helps us to compare the AOP languages with each other.\ud Furthermore, it exposes the issues that have to be considered when a new\ud aspect-oriented language needs to be developed.\ud In this thesis, we analyse the four main aspect-oriented concepts of the reference\ud model, namely join point, pointcut, advice and aspect, and identify problems\ud related to their use in various AOP languages. Based on this analysis, we\ud propose extensions of the existing concepts and/or design new ones to address\ud the identified problems.\ud In current aspect-oriented languages, pointcuts select join points of a program\ud based on lexical information such as explicit names of program elements.\ud However, this reduces the adaptability of software, since it involves too much\ud information that is hard-coded, and often implementation-specific. We claim\ud that this problem can be reduced by referring to program elements through their\ud semantic properties. A semantic property describes for example the behavior\ud of a program element or its intended meaning. We formulate requirements for\ud the proper application of semantic properties in aspect-oriented programming.\ud We discuss how to use semantic properties for the superimposition of aspects,\ud and how to apply superimposition to bind semantic properties to program\ud elements. To achieve this, we propose language constructs that support semantic\ud composition: the ability to compose aspects with the elements of the base\ud program that satisfy certain semantic properties.\ud The current advice-pointcut binding constructs of AOP languages maintain\ud explicit dependencies to advices and aspects. This results in weaving specifications\ud that are less evolvable and need more maintenance during the development\ud of a system. We show that this issue can be addressed by providing associative\ud access to advices and aspects instead of using explicit dependencies in\ud the weaving specification. To this aim, we propose to use a designating (query)\ud language in advice-pointcut bindings that allows for referring aspect/advices\ud through their (syntactic and semantic) properties. We also present how semantic\ud properties can be applied to provide reusable (adaptable) aspect abstractions.\ud Aspect-oriented languages provide means to superimpose aspectual behavior –\ud in terms of advices - on a given set of join points. It is possible that not just a\ud single, but several advices need to execute at the same join point. Such "shared"\ud join points may give rise to issues such as determining the exact execution\ud order and the other possible dependencies among the aspects. We present a\ud detailed analysis of the problem, and identify a set of requirements upon mechanisms\ud for composing aspects at shared join points. To address the identified\ud issues, we propose a general and declarative model for defining constraints\ud upon the possible compositions of aspects at a shared join point. By using an\ud extended notion of join points, we show how concrete aspect-oriented\ud programming languages can adopt the proposed model.\ud The thesis also presents how the proposed extensions and new constructs are\ud adopted by the aspect-oriented language Compose*. To evaluate the proposed\ud constructs, we provide qualitative analyses with respect to various software\ud engineering properties, such as evolvability, modularity, predictability and\ud adaptability

Modeling and Reasoning over Distributed Systems using Aspect-Oriented Graph Grammars

Aspect-orientation is a relatively new paradigm that introduces abstractions to modularize the implementation of system-wide policies. It is based on a composition operation, called aspect weaving, that implicitly modifies a base system by performing related changes within the system modules. Aspect-oriented graph grammars (AOGG) extend the classic graph grammar formalism by defining aspects as sets of rule-based modifications over a base graph grammar. Despite the advantages of aspect-oriented concepts regarding modularity, the implicit nature of the aspect weaving operation may also introduce issues when reasoning about the system behavior. Since in AOGGs aspect weaving is characterized by means of rule-based rewriting, we can overcome these problems by using known analysis techniques from the graph transformation literature to study aspect composition. In this paper, we present a case study of a distributed client-server system with global policies, modeled as an aspect-oriented graph grammar, and discuss how to use the AGG tool to identify potential conflicts in aspect weaving

Extension of Petri Nets by Aspects to Apply the Model Driven Architecture Approach

Within MDA models are usually created in the UML. However, one may prefer to\ud use different notations such as Petri-nets, for example, for modelling concurrency\ud and synchronization properties of systems. This paper claims that techniques that\ud are adopted within the context of MDA can also be beneficial in modelling systems\ud by using notations other than the UML. Petri-Nets are widely used for modelling\ud of business and application logic of information systems with web services. For\ud certain kinds of applications, therefore, Petri Nets can be more suitable for building\ud Computation Independent, Platform Independent and Platform Specific Models\ud (CIM, PIM and PSM). Unfortunately, the well-known problems with separation of\ud concerns in Petri Nets and keeping track of changes may hinder achieving the aim of\ud MDA: building reusable, portable and interoperable models. In this paper we define\ud Aspect Petri Nets as a structure of several Petri Nets and quantification rules for\ud weaving of those Petri Nets. Aspect Petri Nets are suitable for application of MDA;\ud they support traceability of changes and reusability, portability and interoperability\ud of models. We illustrate advantages of modelling in Aspect Petri Nets for MDA\ud application and describe necessary tool support

AOSD Ontology 1.0 - Public Ontology of Aspect-Orientation

This report presents a Common Foundation for Aspect-Oriented Software Development. A Common Foundation is required to enable effective communication and to enable integration of activities within the Network of Excellence. This Common Foundation is realized by developing an ontology, i.e. the shared meaning of terms and concepts in the domain of AOSD. In the first part of this report, we describe the definitions of an initial set of common AOSD terms. There is general agreement on these definitions. In the second part, we describe the Common Foundation task in detail

A taxonomy of asymmetric requirements aspects

The early aspects community has received increasing attention among researchers and practitioners, and has grown a set of meaningful terminology and concepts in recent years, including the notion of requirements aspects. Aspects at the requirements level present stakeholder concerns that crosscut the problem domain, with the potential for a broad impact on questions of scoping, prioritization, and architectural design. Although many existing requirements engineering approaches advocate and advertise an integral support of early aspects analysis, one challenge is that the notion of a requirements aspect is not yet well established to efficaciously serve the community. Instead of defining the term once and for all in a normally arduous and unproductive conceptual unification stage, we present a preliminary taxonomy based on the literature survey to show the different features of an asymmetric requirements aspect. Existing approaches that handle requirements aspects are compared and classified according to the proposed taxonomy. In addition,we study crosscutting security requirements to exemplify the taxonomy's use, substantiate its value, and explore its future directions

An ontology of agile aspect oriented software development

Both agile methods and aspect oriented programming (AOP) have emerged in recent years as new paradigms in software development. Both promise to free the process of building software systems from some of the constraints of more traditional approaches. As a software engineering approach on the one hand, and a software development tool on the other, there is the potential for them to be used in conjunction. However, thus far, there has been little interplay between the two. Nevertheless, there is some evidence that there may be untapped synergies that may be exploited, if the appropriate approach is taken to integrating AOP with agile methods. This paper takes an ontological approach to supporting this integration, proposing ontology enabled development based on an analysis of existing ontologies of aspect oriented programming, a proposed ontology of agile methods, and a derived ontology of agile aspect oriented development