SAP Web应用服务器
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Web应用服务器 (WAS或者Web AS)是NetWeaver解决方案的一个组件。在SAP看来，web应用服务器是他们大部分产品运行的基础。
概览
它的基本功能是用于基于SAP标准解决方案编程语言(通常是ABAP)的web开发，但新版本也允许使用Java语言进行开发。有了web应用服务器，在web环境下基于SAP解决方案基础设施发布查询，程序和ABAP应用就有了可能。新版的WAS也支持像Java这样的开放标准。6.20以上的版本里可以单独创建ABAP程序，Java程序或者两者的混合。
架构
SAP Web应用服务器的架构可以分为五层：
- 表现层：在表现层，用户接口可以使用JSP，BSP或者Web Dynpro技术来开发。下面的业务层通过Java或ABAP程序来提供业务内容。
- 业务层：业务层包括一个通过J2EE认证的运行时环境来出来从ICM传来的请求然后动态产生一个应答。业务逻辑可以用ABAP或者基于J2EE标准的Java来实现。开发人员实现了业务逻辑后可以用J2EE环境的EJB来持续化这些业务逻辑。开发人员还可以访问运行在ABAP环境里的应用的业务对象以从他们的业务逻辑和持续化中获益。
- Integration layer. The local integration engine is an integral part of SAP Web AS and allows instant connection to SAP XI. The local integration engine provides messaging services that exchange messages between the components that are connected in SAP XI.
- Connectivity layer. The Internet Communication Manager (ICM) dispatches user interface requests to the presentation layer and provides a single framework for connectivity using various communication protocols. Currently, modules are available for Hypertext Transfer Protocol (HTTP), HTTPS (extension of HTTP running under the Secure Socket Layer (SSL)), Simple Mail Transfer Protocol (SMTP), Simple Object Access Protocol (SOAP), and Fast Common Gateway Interface (FastCGI).
- Persistence layer. The persistence layer supports database independence and scalable transaction handling. Business logic can be developed completely independent of the underlying database and operating system. Database independence is also made possible by support for open standards. The database interface ensures optimized data access from within the ABAP environment through Open SQL. SAP propagates the outstanding capabilities of Open SQL for ABAP to Open SQL for Java and offers a variety of standard Application Programming Interfaces (APIs) to application programmers, such as SQLJ. Other technologies, such as Java Data Objects (JDO) and container managed persistence (CMP) for EJB, or the direct use of the Java Database Connectivity (JDBC) API, are also supported.