SOA之SCA/SDO标准体系介绍
原文地址：http://gocom.primeton.com/blog1335_2355.htm?PHPSESSID=2e4f6fd66772bf830065c7b0b3632792
SCA
的基本思想是将业务功能作为一系列服务来提供，这些服务组合到一起，以创建满足特定业务需要的解决方案。这些复合应用程序既可以包含专门为该应用程序创建的新服务，也可以包含来自现有系统和应用程序的业务功能（作为复合应用程序的一部分来重用）。
SCA
为服务组合和服务组件的创建（包括
SCA
复合应用程序内部现有应用程序功能的重用）提供了模型。
SCA
这一模型旨在包含广泛的服务组件技术以及用于连接这些组件的访问方法。对于组件，它不仅包括各种编程语言，还包括通常与这些语言一起使用的框架和环境。对于访问方法，
SCA
复合应用程序允许使用各种常用的通信和服务访问技术，例如，
Web
服务、消息传递系统和远程过程调用（
RPC
）。
SCA
包含以下规范：
SCA EJB
组件模型
SCA Java EJB
客户及实现（
SCA Java EJB Client and Implementation
）规范描述了如何在
SCA
复合应用程序中使用
EJB
和
EJB
模块。它在两个层次上定义了
EJB
的使用：
l
可以将完整的
EJB
模块像
SCA
复合体一样使用，不需要做任何内部细节上的改动，借助
SCA
连接到
EJB
模块提供的服务上，并将
EJB
模块的服务需求连接到
EJB
模块的外部组件所提供的服务上。
SCA
装配模型
非功能性需求（例如安全性）的捕获和表示是服务定义的一个重要方面，在组件和复合应用程序的整个生命周期中都会对
SCA
产生影响。
SCA
提供了策略框架以支持约束、能力和服务质量（
QoS
）预期的规范，从组件设计直到具体部署。此规范描述了框架及其使用。
SCA Java
公共注释和
API
（
SCA Java Common Annotations and API
）规范定义了
Java API
和注释，以支持使用
Java
编程语言来构建服务组件和服务客户。有一些紧密相关的模型，它们描述了如何在
SOA
上下文中使用其他基于
Java
的框架和模型，例如
Spring
和
EJB
，这些模型也使用此规范定义的公共注释和
API
。此外，
Java
组件实现规范还定义了用于创建服务组件的简单
Java POJO
模型。
进行粗粒度的集成：与
Spring
的集成将在
SCA
复合体层次进行，其中
Spring
应用程序上下文提供了完整的
SCA
复合体，并通过
SCA
暴露的服务和服务需求。这意味着
Spring
应用程序上下文定义了
SCA
复合体的具体实现的内部结构。
从
Spring
上下文开始：可以将任何有效的
Spring
应用程序上下文用作
SOA
中的组件实现。特别地，应该可以从任何
Spring
上下文生成
SCA
复合应用程序，并在“
SCA
装配”中使用这些复合应用程序。
SCA
绑定规范
Web
服务绑定允许利用
Web
服务技术来访问外部需求或公开
SCA
服务。
SCA
提供了服务组件之间的互连的复合视图，而
Web
服务提供了用于访问服务组件的互操作方式。
Web
服务绑定还提供了
SCA
系统与其他服务之间的互操作衔接，这里的其他服务是指
SCA
系统的外部服务，但它们供
SCA
复合体使用。
EJB Session Bean
绑定可以将先前部署的
Session Bean
集成到
SCA
装配中，并允许向使用
EJB
编程模型的客户公开
SCA
服务。
EJB
绑定既支持无状态的
Session Bean
模型也支持有状态的
Session Bean
模型。
服务数据对象（
SDO
）的设计是为了简化和统一应用程序处理数据的方式。利用
SDO
，应用程序编程人员可以一致地访问和操纵来自异构数据源的数据，包括关系数据库、
XML
数据源、
Web
服务和企业信息系统。
为支持各种可能的应用，标准中包括了对各种常用语言的支持，包括：
SDO for Java and C++
，
SDO for PHP
，
SDO for C
，
SDO for COBOL
。详细内容可以从相关的白皮书和规范正文中获得。
Open CSA promotes the creation and adoption of the
Service Component Architecture (SCA) and
Service Data Objects (SDO) families of specifications.
These specifications are currently available for download from the
Open SOA Collaboration.
Service Component Architecture (SCA)
Service Component Architecture (
SCA) is a set of specifications which describe a model for building applications and systems using a Service-Oriented Architecture (
SOA).
SCA extends and complements prior approaches to implementing services, and
SCA builds on open standards such as Web services.
SCA is based on the idea that business function is provided as a series of services, which are assembled together to create solutions that serve a particular business need. These composite applications can contain both new services created specifically for the application and also business function from existing systems and applications, reused as part of the composition.
SCA provides a model both for the composition of services and for the creation of service components, including the reuse of existing application function within
SCA compositions.
SCA is a model that aims to encompass a wide range of technologies for service components and for the access methods which are used to connect them. For components, this includes not only different programming languages, but also frameworks and environments commonly used with those languages. For access methods,
SCA compositions allow for the use of various communication and service access technologies that are in common use, including, for example, Web services, messaging systems and Remote Procedure Call (RPC).
SCA comprises the following specifications:
SCA EJB Component Model
The
SCA Java EJB Client and Implementation specification describes how EJBs and EJB modules can be used within an
SCA composition. The usage is defined at two levels:
·It is possible to use complete EJB modules as if they are
SCA composites, without changing their internal details, using
SCA to wire to services offered by EJBs in the module and wiring from unsatisifed EJB-refs of the module to services provided by components outside the EJB module.
·It is possible to use individual EJBs with
SCA providing all the wiring
This specification can be downloaded from the
Open SOA Collaboration. For more information, see the
Open SOA EJB white paper.
SCA Assembly Model
The
SCA Assembly Model consists of a series of artifacts which define the configuration of an
SCA system in terms of service components which implement and/or use services and the connections which describe how they are linked together. The assembly is defined in terms of a set of
SCA composites, which define components and reference the implementation code that provide business function and which also describe services and references and the wires that link them.
This specification can be downloaded from the
Open SOA Collaboration.
SCA Policy Framework
The capture and expression of non-functional requirements such as security is an important aspect of service definition, and has impact on
SCA throughout the lifecycle of components and compositions.
SCA provides the
Policy Framework to support specification of constraints, capabilities and Quality of Service (QoS) expectations, from component design through to concrete deployment. This specification describes the framework and its usage.
This specification can be downloaded from the
Open SOA Collaboration.
SCA Java Annotations, APIs, and Component Implementation
The
SCA Java Common Annotations and APIs specification defines Java APIs and annotations that enable service components and service clients to be built in the Java programming language. There are closely related models describing how other Java-based frameworks and models can be used in the context of
SCA, such as Spring and EJBs, which also use the common annotations and APIs defined here. In addition, the
Java Component Implementation specification defines a simple Java POJO model for creating service components.
This specification can be downloaded from the
Open SOA Collaboration.
SCA Client & Implementation: C++
The
SCA C++ Client and Implementation (C++ C&I) specification defines APIs and annotations which enable service components and service clients to be written in C++ which fit with the broader
SCA Assembly model for
SOA solutions.
This specification can be downloaded from the
Open SOA Collaboration.
The
SCA WS-BPEL Client and Implementation (BPEL C&I) model specifies how WS-
BPEL processes can be used as
SCA components.
This specification can be downloaded from the
Open SOA Collaboration.
SCA Client & Implementation: PHP
The
SCA Client and Implementation model for PHP defines how PHP scripts and objects can be used within an
SCA assembly.
This specification can be downloaded from the
Open SOA Collaboration.
SCA Client & Implementation: Spring
The
SCA Java Client and Implementation model for Spring specifies how the Spring Framework can be used with
SCA. The goals of this effort are:
Coarse-grained integration: The integration with Spring will be at the
SCA Composite level, where a Spring application context provides a complete composite, exposing services and using references via
SCA. This means that a Spring application context defines the internal structure of a composite implementation.
Start from SCA Component Type: It should be possible to use Spring to implement any
SCA Composite that uses WSDL or Java interfaces to define services, possibly with some
SCA specific extensions.
Start from Spring context: It should be possible to use any valid Spring application context as the implementation of a component within
SCA. In particular, it should be possible to generate an
SCA Composite from any Spring context and use that composite within an
SCA assembly.
This specification can be downloaded from the
Open SOA Collaboration.
SCA Bindings Specifications
SCA Bindings apply to services and references. Bindings allow services to be provided, and references to be satisfied, via particular access methods or transports.
The
Web service bindings allow one to access an external reference or expose
SCA services using Web services technologies.
SCA provides a compositional view of interconnections among service components whereas Web services provide an interoperable way to access the service components. The Web service binding also provides the interoperability glue between an
SCA system and other services that are external to the
SCA system but are used by composites within the
SCA system.
The
JMS binding allows
SCA components to communicate using the JMS API. It provides JMS-specific details of the connection to the required JMS resources. It supports the use of Queue and Topic type destinations.
The
EJB Session Bean bindings integrate a previously deployed session bean into an
SCA assembly, and allows one to expose
SCA services to clients which use the EJB programming model. The EJB binding supports the stateless session bean model as well as the stateful session bean model.
This specification can be downloaded from the
Open SOA Collaboration. For more information, see the
Open SOA SCA Bindings page.
Service Data Objects (SDO)
Service Data Objects (
SDO) are designed to simplify and unify the way in which applications handle data. Using
SDO, application programmers can uniformly access and manipulate data from heterogeneous data sources, including relational databases, XML data sources, Web services, and enterprise information systems.
These specifications can be downloaded from the
Open SOA Collaboration.
For more information, see the
SDO v2.1 white paper.
SDO for Java and C++
These specifications can be downloaded from the
Open SOA Collaboration.
SDO for PHP
Service Data Objects (
SDOs) enable PHP applications to work with data from different sources, such as databases and XML files, using a single interface. The
PHP implementation of SDO is the first to map
SDO to a weakly and dynamically typed scripting environment. The result is a technology which, at its heart provides the same functionality and compatibility as other implementations, but externally present an API that is tailored to the target language.
For more information, see the
SDO for PHP white paper.
SDO for C
An
SDO for C draft specification proposal is available from the Open
SOA Collaboration.
SDO for COBOL
An
SDO for COBOL draft specification proposal is available from the Open
SOA Collaboration.
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SOA之SCA/SDO标准体系介绍
发布时间:2007年09月28日 作者:yangjw阅读次数:2169次 类别:看营销 永久链接 Trackback |
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