WebService实现包--AXIS2

babycrying 2009-12-11

深度探索 Axis2:AXIOM:

http://www.ibm.com/developerworks/cn/webservices/ws-java2/index.html

 http://blog.csdn.net/tafu/article/details/524116

Axis2是全新设计的,在2004年的“Axis峰会”上,大家决定采用新的架构来让Axis更加的富有弹性,更有效率,并且更加的可配置。Axis2现在具有的一些feature:

Speed

Low memory foot print

AXIOM - AXis Object Model

Hot Deployment

Asynchronous Web Services

MEP Support - Message Exchange Patterns

Flexibility

Stability

Component-oriented deployment

Transport framework

WSDL support

有些feature现在看不懂,还是先动手做一下,感性认识一下吧

第一步:下载AXIS2。http://ws.apache.org/axis2/download.cgi 。很有趣,在apache的Web Service 的Project目录下面还看不到AXIS2。要下那个binary的版本,因为里面有例程。

第二步:Copy axis2.war到$TOMCAT_HOME/webapps目录下面。Tomcat好像只能用JDK1.4,我在JDK1.5 用不出来。

第三步:打开 http://localhost:8080/axis2 ,就可以看到axis2的Welcome页面了。点一下Validate 和Services,看是不是都没有错误。都没有错误的话,就表示deploy成功了。那个adminstration页面可以通过上传文件来hot deploy Web service,可以用来remote deploy。

第四步:研究例程。先从"samples/userguide/src"目录下的例程看起。看到写一个web service很简单嘛:

public class MyService {

  public OMElement echo(OMElement element) throws XMLStreamException {

  //Praparing the OMElement so that it can be attached to another OM Tree.

  //First the OMElement should be completely build in case it is not fully built and still

  //some of the xml is in the stream.

  element.build();

  //Secondly the OMElement should be detached from the current OMTree so that it can be attached

  //some other OM Tree. Once detached the OmTree will remove its connections to this OMElement.

  element.detach();

  return element;

  }

  public void ping(OMElement element) throws XMLStreamException {

  //Do some processing

  }

  public void pingF(OMElement element) throws AxisFault{

  throw new AxisFault("Fault being thrown");

  }

  }

 看得出来,函数统一使用OMElement作为参数。在META-INF目录下面有个services.xml文件:

 <service name="MyService">

  <description>

  This is a sample Web Service with two operations,echo and ping.

  </description>

  <parameter name="ServiceClass" locked="false">userguide.example1.MyService</parameter>

  <operation name="echo">

  <messageReceiver class="org.apache.axis2.receivers.RawXMLINOutMessageReceiver"/>

  </operation>

  <operation name="ping">

  <messageReceiver class="org.apache.axis2.receivers.RawXMLINOnlyMessageReceiver"/>

  </operation>

  </service>

呵呵,也很简单嘛。有返回值的就用RawXMLINOutMessageReceiver,没返回值的就用RawXMLINOnlyMessageReceiver。把它们编译(要把axis2的jar写到classpath里去)打包压到 MyService.aar,包里文件目录如下:

./\META-INF/services.xml

./userguide/example1/MyService.class

把MyService.aar拷贝到$TOMCAT_HOME/webapps/axis2/WEB-INF/services,然后去点一下http://localhost:8080/axis2 页面上的Services,也就是http://localhost:8080/axis2/listServices.jsp ,就可以看到MyService已经被列出来了。

客户端的调用

Web services提供的服务多种多样,有的可以马上获得结果,有的要消耗很长的时间。所以,如果我们需要多种调用方式来对付不同的情况。

大多数的Web services都提供阻塞(Blocking)和非阻塞(Non-Blocking)两种APIs.

这两个概念以前应该学过,简单说一下。

Blocking API - 调用端要等被调用的函数运行完毕才继续往下走。

Non-Bloking API - 调用端运行完调用函数以后就直接往下走了,调用端和被调用端是异步执行的。返回值是用回调函数来实现的。

这种异步叫做API层异步(API Level Asynchrony)。他们只用到一个连接来发送和接收消息,而且,如果是那种需要运行很长时间的函数,还会碰到Time Out 错误,如果用两个连接分别处理发送和接收消息,调用的时间就可以缩短,也可以解决Time Out 问题。用两个连接来分别处理发送和接收消息,叫做传输层异步(Transport Level Asynchrony)。

WebService实现包--AXIS2

 理论真无聊,还是来看实例吧。

打开 Eclipse, 创建一个新Project, 新建一个叫userguide.clients的包, 把"samples\userguide\src\userguide\clients" 下面的文件都copy到那个包下面, 把AXIS2的lib下面的jar都加到ilbrary里面去(应该不用全加,懒一点就全加了吧.) 发现了关于echo的调用的方式, 居然有五个:

EchoBlockingClient

EchoBlockingDualClient

EchoBlockingWsaBasedClient

EchoNonBlockingClient

EchoNonBlockingDualClient

一个一个看吧.

EchoBlockingClient.java

  public class EchoBlockingClient {

  private static EndpointReference targetEPR = new EndpointReference("http://localhost:8080/axis2/services/MyService");

  public static void main(String[] args) {

  try {

  OMElement payload = ClientUtil.getEchoOMElement();

  Call call = new Call();

  call.setTo(targetEPR);

  call.setTransportInfo(Constants.TRANSPORT_HTTP,

  Constants.TRANSPORT_HTTP,

  false);

  //Blocking invocation

  OMElement result = call.invokeBlocking("echo",

  payload);

  StringWriter writer = new StringWriter();

  result.serializeWithCache(XMLOutputFactory.newInstance()

  .createXMLStreamWriter(writer));

  writer.flush();

  System.out.println(writer.toString());

  } catch (AxisFault axisFault) {

  axisFault.printStackTrace();

  } catch (XMLStreamException e) {

  e.printStackTrace();

  }

  }

  }

和一代几乎一样, 弄一个EndpointReference, 再弄一个call, 其他不一样,但是也很简单, 弄一个OMElement作为参数, 返回也是一个OMElement. 可惜运行居然有错.

再来看双通道的版本

EchoBlockingDualClient.java

  public class EchoBlockingDualClient {

  private static EndpointReference targetEPR = new EndpointReference("http://127.0.0.1:8080/axis2/services/MyService");

  public static void main(String[] args) {

  try {

  OMElement payload = ClientUtil.getEchoOMElement();

  Call call = new Call();

  call.setTo(targetEPR);

  call.engageModule(new QName(Constants.MODULE_ADDRESSING));

  call.setTransportInfo(Constants.TRANSPORT_HTTP,

  Constants.TRANSPORT_HTTP,

  true);

  //Blocking Invocation

  OMElement result = call.invokeBlocking("echo",

  payload);

  StringWriter writer = new StringWriter();

  result.serializeWithCache(XMLOutputFactory.newInstance()

  .createXMLStreamWriter(writer));

  writer.flush();

  System.out.println(writer.toString());

  //Need to close the Client Side Listener.

  call.close();

  } catch (AxisFault axisFault) {

  axisFault.printStackTrace();

  } catch (Exception ex) {

  ex.printStackTrace();

  }

  }

  }

 加了一句engageModule, 这句话好像没什么用,我删掉这句话也能运行的, 然后setTransportInfo最后一个参数改成了true. 关于setTransportInfo的三个参数, 第一个是发送的Transport, 第二个是接收的Transport, 第三个是"是否双通道", 支持的搭配形式如下:

http, http, true

http, http, false

http,smtp,true

smtp,http,true

smtp,smtp,true

看下一个吧,EchoNonBlockingClient,这个是单通道的非阻塞模式:

public class EchoNonBlockingClient {

  private static EndpointReference targetEPR = new EndpointReference("http://127.0.0.1:8080/axis2/services/MyService");

  public static void main(String[] args) {

  try {

  OMElement payload = ClientUtil.getEchoOMElement();

  Call call = new Call();

  call.setTo(targetEPR);

  call.setTransportInfo(Constants.TRANSPORT_HTTP,

  Constants.TRANSPORT_HTTP,

  false);

  //Callback to handle the response

  Callback callback = new Callback() {

  public void onComplete(AsyncResult result) {

  try {

  StringWriter writer = new StringWriter();

  result.getResponseEnvelope().serializeWithCache(XMLOutputFactory.newInstance()

  .createXMLStreamWriter(writer));

  writer.flush();

  System.out.println(writer.toString());

  } catch (XMLStreamException e) {

  reportError(e);

  }

  }

  public void reportError(Exception e) {

  e.printStackTrace();

  }

  };

  //Non-Blocking Invocation

  call.invokeNonBlocking("echo", payload, callback);

  //Wait till the callback receives the response.

  while (!callback.isComplete()) {

  Thread.sleep(1000);

  }

  } catch (AxisFault axisFault) {

  axisFault.printStackTrace();

  } catch (Exception ex) {

  ex.printStackTrace();

  }

  }

  }

不同的地方,只是调用的方法从invokeBlocking变成了invokeNonBlocking,然后写了一个简单的匿名Callback类作为回调函数。关于这个Callback类,它是一个抽象类,其中有两个方法:onComplete和reportError,都是client端必须实现的,他还有一个Field,就是complete,可以用来设置和查询调用是否完成。可惜也不能运行,和上面的错误一样,是在createSOAPMessage的时候报null错误。

看下一个EchoNonBlockingDualClient,非阻塞的双通道:

public class EchoNonBlockingDualClient {

  private static EndpointReference targetEPR = new EndpointReference("http://127.0.0.1:8080/axis2/services/MyService");

  public static void main(String[] args) {

  try {

  OMElement payload = ClientUtil.getEchoOMElement();

  Call call = new Call();

  call.setTo(targetEPR);

  //The boolean flag informs the axis2 engine to use two separate transport connection

  //to retrieve the response.

  call.engageModule(new QName(Constants.MODULE_ADDRESSING));

  call.setTransportInfo(Constants.TRANSPORT_HTTP,

  Constants.TRANSPORT_HTTP,

  true);

  //Callback to handle the response

  Callback callback = new Callback() {

  public void onComplete(AsyncResult result) {

  try {

  StringWriter writer = new StringWriter();

  result.getResponseEnvelope().serializeWithCache(XMLOutputFactory.newInstance()

  .createXMLStreamWriter(writer));

  writer.flush();

  System.out.println(writer.toString());

  } catch (XMLStreamException e) {

  reportError(e);

  }

  }

  public void reportError(Exception e) {

  e.printStackTrace();

  }

  };

  //Non-Blocking Invocation

  call.invokeNonBlocking("echo", payload, callback);

  //Wait till the callback receives the response.

  while (!callback.isComplete()) {

  Thread.sleep(1000);

  }

  //Need to close the Client Side Listener.

  call.close();

  } catch (AxisFault axisFault) {

  axisFault.printStackTrace();

  } catch (Exception ex) {

  ex.printStackTrace();

  }

  }

  }

 双通道和单通道基本没什么不同,只是双通道的时候,它总是要设定engageModule,然后多了一个call.close();,自己关闭监听器(close the Client Side Listener)。以上这些都是需要返回值的调用,如果不需要返回值呢,看看PingClient

public class PingClient {
    private static EndpointReference targetEPR = new EndpointReference("http://localhost:8080/axis2/services/MyService");

    public static void main(String[] args) {
        try {
            OMElement payload = ClientUtil.getPingOMElement();

            MessageSender msgSender = new MessageSender();
            msgSender.setTo(targetEPR);
            msgSender.setSenderTransport(Constants.TRANSPORT_HTTP);

            msgSender.send("ping", payload);

        } catch (AxisFault axisFault) {
            axisFault.printStackTrace();
        }
    }

}

 呵呵,这也忒简单了一点,就一个msgSender.send就搞定了。

Client端的调用组合基本看完了,但是还有一个EchoBlockingWsaBasedClient,这是什么东啊? 还有那个engageModule是用来做啥的?先不管它们吧。

看 看那个我认为最有用的工具:WSDL2Java,在bin目录下面有WSDL2Java.bat和WSDL2Java.sh,这个工具是用来干啥的呢,和 一代一样,是用来生成stub的,就是说别人发布了Web Service以后,就会有一个wsdl文件,这个工具可以根据wsdl生成几个class,把底层的调用都wrap起来了,然后你用的时候就像普通函数 调用一样。
演练一下吧,从命令行走到samples/wsdl目录下面,看到Axis2SampleDocLit.wsdl,执行../.. /bin/WSDL2Java.bat -uri Axis2SampleDocLit.wsdl,目录下面一下子多了两个目录,不管schemaorg_apache_xmlbeans,把 codegen目录copy到Eclipse的一个Project里面去,哇,好多class啊,不看别的,就看 Axis2SampleDocLitPortTypeStub,里面有三个函数是Web Service提供的:echoStringArray,echoStruct和echoString,哈哈,什么Call类 了,MessageContext了,都在里面了,使用起来嘛,就像这样:

try {
     Axis2SampleDocLitPortTypeStub stub= new Axis2SampleDocLitPortTypeStub(null,                                "http://localhost:8080/axis2/services/Axis2SampleDocLitPortType");
     //Create the request document to be sent.
     EchoStringParamDocument  reqDoc= EchoStringParamDocument.Factory.newInstance();
     reqDoc.setEchoStringParam("Axis2 Echo");
     //invokes the web service.
     EchoStringReturnDocument resDoc=stub.echoString(reqDoc);
     System.out.println(resDoc.getEchoStringReturn());

    } catch (Exception e) {
        e.printStackTrace();
    }

 就是创一个stub,再创一个参数类(EchoStringParamDocument),然后调用函数传参数,和普通的函数调用没有区别。如果你在命令行输入WSDL2Java.bat,会看到它的帮助提示如下:
Usage WSDL2Code -uri <Location of WSDL> :WSDL file location
-o <output Location> : output file location
-a : Generate async style code only. Default if off
-s : Generate sync style code only. Default if off. takes precedence over -a
-p <package name> : set custom package name
-l <language> : valid languages are java and csharp. Default is java
-t : Generate TestCase to test the generated code
-ss : Generate server side code (i.e. skeletons).Default is off
-sd : Generate service descriptor (i.e. axis2.xml).Default is off.Valid with -ss

相关推荐