WebService_015：WSIF介绍

【WSIF】：Web Services Invocation Framework Web服务调用框架。
“WSIF is a simple Java API for invoking Web services, no matter how or where the services are provided.”（摘自http://ws.apache.org/wsif/）
WSIF提供了一组简单的API来调用Web服务而不需要了解该Web服务的实现方式。说的再明白些，“WSIF is a WSDL-based API for invoking WSDL-described services”。WSIF支持如下方式实现的服务：SOAP、Java、EJB、JMS、JCA。使用WSDL扩展规范，你可以像访问Web服务一样来访问方式实现的服务。

除了以统一的编程模型来调用Web服务外，WSIF还有以下好处：
◆ 通过WSIF 调用服务可以维护原生协议的性能。因此，在调用 Java 、EJB 或其他资源时，没有性能损失。
◆ WSIF 支持JTA事务。因此，Java 资源可以参与分布式事务。

问题1：What are differences between WSIF and Axis?
Axis is an implementation of SOAP. It includes on the server-side infrastructure for deploying web service implementations and then routing SOAP messages between clients and those implementations. It also implements the JAX-RPC specification for invoking SOAP services.
WSIF is similar to the client piece of Axis, in that it is used for invoking services. However, WSIF's API is WSDL-driven and protocol independent; it allows protocol-specific code ("providers") to be plugged in. For invoking SOAP services, WSIF is in fact packaged with an Axis provider, that uses Axis APIs (i.e. JAX-RPC) to do the invocation. So WSIF operates at a more abstract level than Axis.问题2：What are differences between WSIF and JAX-RPC?JAX-RPC is an API for invoking XML-based RPC services - essentially its current scope is limited to invocation of SOAP services. WSIF is an API for invoking WSDL-described services, whether they happen to be SOAP services or not (for example, WSIF defines WSDL bindings so that EJBs, enterprise software acessible using JMS or the Java Connector architecture as wel as local java classes can all be described as first class WSDL services and then invoked using the same, protocol-independent WSIF API).
问题3：How to use and set HTTP proxy with WSIF and SOAP over HTTP?HTTP proxy settings can be set using the following system properties http.proxyHost- The hostname of the proxy server http.proxyPort - The port for the proxy serverhttp.nonProxyHosts - A comma separated list of hosts to access directly rather thanthrough the proxy

如何使用WSIF？
1. 实验准备
（1）下载WSIF2.0 http://ws.apache.org/wsif/。
（2）下载WSIF2.0 http://ws.apache.org/wsif/。