Aspect] is a simple and practical aspect-oriented extension to Java With just a few new constructs, AspectJ provides support for modular implementation of a range of crosscutting concerns. In AspectJ's dynamic join point model, join points are well-defined points in the execution of the program; pointcuts are collections of join points; advice are special method-like constructs that can be attached to pointcuts; and aspects are modular units of crosscutting implementation, comprising pointcuts, advice, and ordinary Java member declarations. AspectJ code is compiled into standard Java bytecode. Simple extensions to existing Java development environments make it possible to browse the crosscutting structure of aspects in the same kind of way as one browses the inheritance structure of classes. Several examples show that AspectJ is powerful, and that programs written using it are easy to understand.

An overview of AspectJ

http://emamispnu.persiangig.com/Projects/Cloud%20Computing/science_2.pdf

Review: A survey on security issues in service delivery models of cloud computing

Service-oriented architectures (SOA) is an emerging approach that addresses the requirements of loosely coupled, standards-based, and protocol- independent distributed computing. Typically business operations running in an SOA comprise a number of invocations of these different components, often in an event-driven or asynchronous fashion that reflects the underlying business process needs. To build an SOA a highly distributable communications and integration backbone is required. This functionality is provided by the Enterprise Service Bus (ESB) that is an integration platform that utilizes Web services standards to support a wide variety of communications patterns over multiple transport protocols and deliver value-added capabilities for SOA applications. This paper reviews technologies and approaches that unify the principles and concepts of SOA with those of event-based programing. The paper also focuses on the ESB and describes a range of functions that are designed to offer a manageable, standards-based SOA backbone that extends middleware functionality throughout by connecting heterogeneous components and systems and offers integration services. Finally, the paper proposes an approach to extend the conventional SOA to cater for essential ESB requirements that include capabilities such as service orchestration, "intelligent" routing, provisioning, integrity and security of message as well as service management. The layers in this extended SOA, in short xSOA, are used to classify research issues and current research activities.

/pdf/service-oriented-architectures-approaches-technologies-and-1m0bcwz0fm.pdf

Service oriented architectures: approaches, technologies and research issues

Over the Internet today, computing and communications environments are significantly more complex and chaotic than classical distributed systems, lacking any centralized organization or hierarchical control. There has been much interest in emerging Peer-to-Peer (P2P) network overlays because they provide a good substrate for creating large-scale data sharing, content distribution, and application-level multicast applications. These P2P overlay networks attempt to provide a long list of features, such as: selection of nearby peers, redundant storage, efficient search/location of data items, data permanence or guarantees, hierarchical naming, trust and authentication, and anonymity. P2P networks potentially offer an efficient routing architecture that is self-organizing, massively scalable, and robust in the wide-area, combining fault tolerance, load balancing, and explicit notion of locality. In this article we present a survey and comparison of various Structured and Unstructured P2P overlay networks. We categorize the various schemes into these two groups in the design spectrum, and discuss the application-level network performance of each group.

/pdf/a-survey-and-comparison-of-peer-to-peer-overlay-network-cpcv2ij1hk.pdf

A survey and comparison of peer-to-peer overlay network schemes

[서평]「Component Software」 - Beyond Object-Oriented Programming -

Web services have become a universal technology for integration of distributed and heterogeneous applications over the Internet. Many recent proposals such as the Business Process Modeling Language (BPML) and the Business Process Execution Language for Web Services (BPEL4WS) focus on combining existing web services into more sophisticated web services. However, these standards exhibit some limitations regarding modularity and flexibility. In this paper, we advocate an aspect-oriented approach to web service composition and present AO4BPEL, an aspect-oriented extension to BPEL4WS. With aspects, we capture web service composition in a modular way and the composition becomes more open for dynamic change.

/pdf/aspect-oriented-web-service-composition-with-ao4bpel-5awsfzmtt5.pdf

Aspect-oriented web service composition with AO4BPEL

Process-oriented composition languages such as BPEL allow Web Services to be composed into more sophisticated services using a workflow process. However, such languages exhibit some limitations with respect to modularity and flexibility. They do not provide means for a well-modularized specification of crosscutting concerns such as logging, persistence, auditing, and security. They also do not support the dynamic adaptation of composition at runtime. In this paper, we advocate an aspect-oriented approach to Web Service composition and present the design and implementation of AO4BPEL, an aspect-oriented extension to BPEL. We illustrate through examples how AO4BPEL makes the composition specification more modular and the composition itself more flexible and adaptable.

http://www.inf.ufsc.br/%7Efrank/INE6514/Artigos2012/AO4BPEL%20-%20An%20Aspect-Oriented%20Extension%20to%20BPEL.pdf

AO4BPEL: An Aspect-oriented Extension to BPEL

Over the last few years several process-based web service composition languages have erged, such as BPEL4WS and BPML. These languages define the composition on the basis of a process that specifies the control and data flow among the services to be composed. In this approach, the whole business logic underlying the composition including business policies and constraints is coded as a monolithic block. As a result, business rules are hard to change without affecting the core composition logic. In this paper, we propose a hybrid composition approach: The composition logic is broken down into a core part (the process) and several well-modularized business rules that exist and evolve independently. We also discuss two alternative technologies for implenting business rules in encapsulated units, using aspects and a rule-based engine. Our approach allows for a more modular and flexible web service composition.

/pdf/hybrid-web-service-composition-business-processes-meet-4fz91cdu6x.pdf

Hybrid web service composition: business processes meet business rules

Web Service composition languages promise a cheap and effective means for application integration over the Internet as in typical B2B interaction scenarios. BPEL is the upcoming standard for Web Service composition and several implementations of it are already available. However, for Web Service composition languages to keep their promises it is essential to provide more support for security. Companies will embrace Web Service composition languages only if their requirements of confidentiality, integrity, authentication, etc. are fulfilled. In this paper, we look at security in Web Services compositions and present a framework for securing BPEL compositions using WS-Security and WS-Policy. The main components of our framework are the process container implemented by a set of aspects in AO4BPEL, an aspect-oriented extension to BPEL, the security service and the deployment descriptor. We also introduce the notion of policy-based process deployment to check the compatibility of the security policies of the composition and its partners at deployment time.

Using aspects for security engineering of Web service compositions

Several approaches have been proposed to introduce self-management capabilities for web service compositions.However, most of these works are limited as they are not extensible, i.e., new self-adaptation features cannot be supported, and even if that is possible then still this cannot be done dynamically while the composite services are running.In addition, many of these works are not based on the service composition standard WS-BPEL. In this paper, we propose a plug-in architecture for self-adaptive web service composition, in which self-adaptation features are well-modularized in aspect based plug-ins. Our approach supports application-specific adaptation scenarios, is easily extensible, and allows self-adaptation logic to be hot-deployed on running process instances. We have implemented this architecture and several plug-ins using the dynamic aspect-oriented workflow language AO4BPEL.

Anis Charfi

Papers

Aspect-oriented web service composition with AO4BPEL

AO4BPEL: An Aspect-oriented Extension to BPEL

Hybrid web service composition: business processes meet business rules

Using aspects for security engineering of Web service compositions

A Plug-in Architecture for Self-Adaptive Web Service Compositions