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

ThetextitService Component Architecture (SCA) is a technology-independent standard for developing distributed Service-oriented Architectures (SOA). The SCA standard promotes the use of components and architecture descriptors, and mostly covers the lifecycle steps of implementation and deployment. Unfortunately, SCA does not address the governance of SCA applications and provides no support for the maintenance of deployed components. This article covers this issue and introduces the FRASCATI platform, a run-time support for SCA with dynamic reconfiguration capabilities and run-time management features. This article presents the internal component-based architecture of the FRASCATI platform, and highlights its key features. The component-based design of the FRASCATI platform introduces many degrees of flexibility and configurability in the platform itself and it can host the SOA applications. This article reports on micro-benchmarks highlighting that run-time manageability in the FRASCATI platform does not decrease its performance when compared with the de facto reference SCA implementation: Apache TUSCANY. Finally, a smart home scenario illustrates the extension capabilities and the various reconfigurations of the FRASCATI platform. Copyright © 2011 John Wiley & Sons, Ltd.

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A component-based middleware platform for reconfigurable service-oriented architectures

Web services have been used for many years. In this time, developers and architects have encountered a number of recurring design challenges related to their usage, and have learned that certain service design approaches work better than others to solve certain problems. In Service Design Patterns, Rob Daigneau codifies proven design solutions for web services that follow the REST architectural style or leverage the SOAP/WSDL specifications. This catalogue identifies the fundamental topics in web service design and lists the common design patterns for each topic. All patterns identify the context in which they may be used, explain the constituent design elements, and explore the relative strengths and trade-offs. Code examples are provided to help you better understand how the patterns work but are kept general so that you can see how the solutions may be applied to disparate technologies that will inevitably change in the years to come. This book will help readers answer the following questions: How do you create a web service API, what are the common API styles, and when should a particular style be used? How can clients and web services communicate, and what are the foundations for creating complex conversations in which multiple parties exchange data over extended periods of time? What are the options for implementing web service logic, and when should a particular approach be used? How can clients become less coupled to the underlying systems used by a service? How can information about a web service be discovered? How can generic functions like authentication, validation, caching, and logging be supported on the client or service? What changes to a service cause clients to break? What are the common ways to version a service? How can web services be designed to support the continuing evolution of business logic without forcing clients to constantly upgrade? This book is an invaluable resource for enterprise architects, solution architects, and developers who use web services to create enterprise IT applications, commercial or open source products, and Software as a Service (SaaS) products that leverage emerging Cloud platforms.

Service Design Patterns: Fundamental Design Solutions for SOAP/WSDL and RESTful Web Services

One of the challenging problems for software developers is guaranteeing that a system as built is consistent with its architectural design. In this paper, we describe a technique that uses run time observations about an executing system to construct an architectural view of the system. With this technique, we develop mappings that exploit regularities in system implementation and architectural style. These mappings describe how low-level system events can be interpreted as more abstract architectural operations. We describe the current implementation of a tool that uses these mappings, and show that it can highlight inconsistencies between implementation and architecture.

DiscoTect: a system for discovering architectures from running systems

第１章 概要 第２章 Ｊ２ＥＥプラットフォームのテクノロジ 第３章 クライアント層 第４章 Ｗｅｂ層 第５章 Ｅｎｔｅｒｐｒｉｓｅ ＪａｖａＢｅａｎｓ層 第６章 エンタープライズ情報システム層 第７章 パッケージ化と配備 第８章 トランザクション管理 第９章 セキュリティ 第１０章 サンプルアプリケーション

Java 2 platform, enterprise editionアプリケーション設計ガイド

JBoss is an extensible, reflective, and dynamically reconfigurable Java application server. It includes a set of components that implement the J2EE specification, but its scope goes well beyond J2EE. JBoss is open-ended middleware, in the sense that users can extend middleware services by dynamically deploying new components into a running server. We believe that no other application server currently offers such a degree of extensibility. This paper focuses on two major architectural parts of JBoss: its middleware component model, based on the JMX model, and its meta-level architecture for generalized EJBs. The former requires a novel class loading model, which JBoss implements. The latter includes a powerful and flexible remote method invocation model, based on dynamic proxies, and relies on systematic usage of interceptors as aspect-oriented programming artifacts.

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The JBoss extensible server

This paper discusses a realization of object persistence in a CORBA-based distributed system In our approach, persistence of CORBA objects is accomplished by the integration of the ORB with an ODBMS This approach is not limited to pure object-oriented database systems, as the ODBMS may be a combination of a relational DBMS and an object-relational mapper The design and implementation of an Object Database Adapter that integrates an ORB and an ODBMS with C++ bindings is presented The ODA uses delegation (rather than inheritance) to connect user-provided implementation classes and IDL-generated classes Only the user-defined parts of CORBA objects are actually stored in a database Their IDL-generated parts are dynamically instantiated, in transient memory, by the ODA Persistent relationships between CORBA objects within a server are not realized at the CORBA level, but at the level of implementation objects Database traversals and queries can therefore be executed at ODBMS speeds The paper discusses in some detail a number of implementation issues, such as caching ODA support to local transactions, ODA interfaces, and CORBA server organization are also examined

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Making CORBA objects persistent: the object database adapter approach

One of the main issues in modern aspect-oriented programming languages and frameworks is the expressiveness of the pointcut language or mechanism. The expressiveness of pointcut languages directly impacts pointcut quality, a property that can be decisive for the effectiveness of aspect implementations. In this paper we propose join point selectors as a simple extension mechanism for enriching current pointcut languages with constructs that play the role of "new primitive pointcuts". Join point selectors allow the creation of pointcuts with greater semantic value. Although similar mechanisms can be found in some existing approaches, the underlying concept has not yet been clearly defined nor fully explored. We present a simple architecture for adding join point selectors to an existing aspect-oriented framework. We show examples of usage of join point selectors to enhance the quality of pointcuts and make aspect development easier. We also show how join point selectors can be used as framework-specific selectors, which allow aspects to cross the boundary of a given framework while still respecting the modularity of that framework.

Join point selectors

JBoss is an extensible Java application server that affords remote access to EJB components via multiple protocols. Its IIOP module supports IIOP-enabled EJBs, which are accessible both to RMI/IIOP clients written in Java and to CORBA clients written in various languages. While other systems use compilation-based approaches to generate IIOP stubs and skeletons, JBoss employs reflective techniques to avoid extra compilation steps and support on-the-fly deployment.

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Dynamic Deployment of IIOP-Enabled Components in the JBoss Server

XActor is a distributed transaction manager that affords transactional remote invocations over an open-ended set of transports. Its support to transactional interactions is dynamic, in the sense that the transaction manager fully exploits a collection of RMI mechanisms and transport protocols that grows with the addition of plug-in modules to running instances of XActor. A distributed transaction can employ any combination of the transports that the currently installed plug-ins provide. Two-phase commit (logging and failure recovery included) runs over any such combination of transports. Aimed at server-side application containers, XActor can be integrated with those systems in a way that allows its plug-in modules to take advantage of the dynamic deployment facilities of the container environment.

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Francisco Reverbel

Papers

The JBoss extensible server

Making CORBA objects persistent: the object database adapter approach

Join point selectors

Dynamic Deployment of IIOP-Enabled Components in the JBoss Server

Dynamic support to transactional remote invocations over multiple transports