Creating and Deploying an Axis Web Service: Differences between Apache Axis and SOAP

Creating a Consumer with Axis

Creating consumers with Axis is really not that much different than the examples in Chapter 7. There are some different include files and a tool to create proxy code much like the WSDL tool found in .NET, but the concept of creating consumers is the same.

In this chapter, we focus on creating a simple command line consumer and the same program that creates a proxy. Using Axis within JSP and other consumers is covered in Chapter 9. which is a case study of using .NET and Java Web Services together.

Command Line Application

The following code is a simple command line application that invokes the Axis Web Service example shown earlier in the chapter. The example starts off by defining all the different Java libraries needed for this example with the import statements. Then there is a class definition followed by the definition of the main method.

Then the example begins to call the Web Service by reading the options passed in from the command line, creating a call to the URL where the Web Service resides, defining the class and method to call from the server, defining the result, and finally printing the result.

    import org.apache.axis.AxisFault;     import org.apache.axis.client.Call;     import org.apache.axis.client.Service;     import org.apache.axis.encoding.XMLType;     import org.apache.axis.utils.Options;     import javax.xml.rpc.ParameterMode;     import javax.xml.namespace.QName;     import;     public class getSimpleStock {         public static void main (String[] args)         throws Exception {       String symbol = null;       //get command line args       Options  myOpts    = new Options( args );       args = myOpts.getRemainingArgs();       //begin a call to a Web Service       Service  myService = new Service();       Call     myCall    = (Call) myService.createCall();       //location of axis server       myOpts.setDefaultURL(       "http://localhost:8000/axis/servlet/AxisServlet" );       myCall.setTargetEndpointAddress       ( new URL(myOpts.getURL()) );       myCall.setUseSOAPAction( true );       //the method to call       myCall.setSOAPActionURI( "getTestQuote" );       //how to encode the request/response       myCall.setEncodingStyle       ("" );       //define the class and method used       myCall.setOperationName( new       QName("SimpleStockExample", "getTestQuote") );       //add symbol to the request       myCall.addParameter       ( "symbol", XMLType.XSD_STRING, ParameterMode.IN );       myCall.setReturnType( XMLType.XSD_FLOAT );       //make the actual object call       Object myResult =       myCall.invoke( new Object[] { symbol = args[0] } );       //print the result       System.out.println("This is the returned value: " +       ((Float)myResult).floatValue());      } }

If you compare this to the examples in Chapter 6, this is a lot of code to write to call a Web Service when compared to .NET—especially since this code needs to be used each time one particular method gets called.

To make calling a Web Service easier with Apache tools, Axis comes with WSDL2Java application that generates Java proxy code to make calling the Web Service easier and quicker. The next section covers the creation of this proxy.

Using WSDL2Java to Create a Proxy

With Axis, WSDL is generated automatically and can be seen by simply putting “wsdl” in the query string. Consider the following URL: http://localhost:8080/axis/ services/SimpleStockExample?wsdl

This will display the WSDL for the SimpleStockExample Web Service shown earlier in this chapter. Figure 8.11 shows how the WSDL appears in Internet Explorer.

click to expand
Figure 8.11: The WSDL output for the SimpleStockExample Web Service.

To create a Java proxy for a client to use, execute WSDL2Java and send the URL of the SimpleStockQuote’s WSDL output. The command should look something like the following.

  java org.apache.axis.wsdl.WSDL2Java   http://localhost:8080/axis/services/SimpleStockExample?wsdl 

This creates a directory called localhost. Within that directory you will find the following four files.

SimpleStockExample and SimpleStockExampleService are both interfaces that define the functionality that the other two Java files must implement. SimpleStockExampleServiceLocator implements SimpleStockExampleService and defines the location of the Web Service and methods. implements and handles the code related to the call.

The following is the code for

     /**      *      *      * This file was auto-generated from WSDL      * by the Apache Axis WSDL2Java emitter.      */     package localhost;     public interface SimpleStockExample extends        java.rmi.Remote {        public float getTestQuote(java.lang.String in0)        throws java.rmi.RemoteException;     }

Notice how the code simply defines an interface, and notice how utilizes this interface.

    /**      *      *      * This file was auto-generated from WSDL      * by the Apache Axis WSDL2Java emitter.      */     package localhost;     public class SimpleStockExampleServiceLocator extends     org.apache.axis.client.Service implements      localhost.SimpleStockExampleService {     // Use to get a proxy class for SimpleStockExample     private final java.lang.String     SimpleStockExample_address =     "http://localhost:8080/axis/services/SimpleStockExample";     public String getSimpleStockExampleAddress() {         return SimpleStockExample_address;     }     public localhost.SimpleStockExample     getSimpleStockExample() throws     javax.xml.rpc.ServiceException { endpoint;         try {             endpoint = new            (SimpleStockExample_address);         }         catch ( e) {             return null;         }         return getSimpleStockExample(endpoint);     }     public localhost.SimpleStockExample     getSimpleStockExample( portAddress) throws     javax.xml.rpc.ServiceException {         try {             return new             localhost.SimpleStockExampleSoapBindingStub            (portAddress, this);         }         catch (org.apache.axis.AxisFault e) {             return null; // ???         }     }     /**      * For the given interface, get the stub      * implementation.      * If this service has no port for the given interface,      * then ServiceException is thrown.      */     public java.rmi.Remote getPort(Class        serviceEndpointInterface) throws        javax.xml.rpc.ServiceException {         try {       if       (localhost.SimpleStockExample.class.isAssignableFrom       (serviceEndpointInterface)) {                 return new        localhost.SimpleStockExampleSoapBindingStub       (new, this);             }         }         catch (Throwable t) {             throw new javax.xml.rpc.ServiceException(t);         }         throw new javax.xml.rpc.ServiceException("There is         no stub implementation for the interface:  " +        (serviceEndpointInterface == null ? "null" :         serviceEndpointInterface.getName()));     } }

The previous Java code is mainly centered on finding the name of the service. The following code snippet is This defines the interface for the actually getting values from the Web Service.

    /**      *      *      * This file was auto-generated from WSDL      * by the Apache Axis WSDL2Java emitter.      */     package localhost;     public interface SimpleStockExampleService extends     javax.xml.rpc.Service {     public String getSimpleStockExampleAddress();     public localhost.SimpleStockExample     getSimpleStockExample() throws     javax.xml.rpc.ServiceException;     public localhost.SimpleStockExample     getSimpleStockExample( portAddress) throws     javax.xml.rpc.ServiceException;     } 

Finally, contains the code defined in the previous interface. This code focuses on creating the call and getting values back from the Web Service.

    /**      *      *      * This file was auto-generated from WSDL      * by the Apache Axis WSDL2Java emitter.     */     package localhost;     public class SimpleStockExampleSoapBindingStub extends     org.apache.axis.client.Stub implements     localhost.SimpleStockExample {     private java.util.Vector cachedSerClasses     = new java.util.Vector();     private java.util.Vector cachedSerQNames     = new java.util.Vector();     private java.util.Vector cachedSerFactories     = new java.util.Vector();     private java.util.Vector cachedDeserFactories     = new java.util.Vector();     public SimpleStockExampleSoapBindingStub() throws     org.apache.axis.AxisFault {          this(null);     }     public SimpleStockExampleSoapBindingStub    ( endpointURL,     javax.xml.rpc.Service service) throws     org.apache.axis.AxisFault {          this(service);          super.cachedEndpoint = endpointURL;     }     public SimpleStockExampleSoapBindingStub    (javax.xml.rpc.Service service) throws     org.apache.axis.AxisFault {         try {             if (service == null) {                 super.service                 = new org.apache.axis.client.Service();             } else {                 super.service = service;             }         }         catch(java.lang.Exception t) {             throw org.apache.axis.AxisFault.makeFault(t);         }     }     private org.apache.axis.client.Call createCall() throws     java.rmi.RemoteException {         try {             org.apache.axis.client.Call call =             (org.apache.axis.client.Call)             super.service.createCall();             if (super.maintainSessionSet) {        call.setMaintainSession(super.maintainSession);             }             if (super.cachedUsername != null) {                 call.setUsername(super.cachedUsername);             }             if (super.cachedPassword != null) {                 call.setPassword(super.cachedPassword);             }             if (super.cachedEndpoint != null) {           call.setTargetEndpointAddress          (super.cachedEndpoint);             }             if (super.cachedTimeout != null) {                 call.setTimeout(super.cachedTimeout);             }             java.util.Enumeration keys =             super.cachedProperties.keys();             while (keys.hasMoreElements()) {                 String key = (String) keys.nextElement();                 if(call.isPropertySupported(key))                     call.setProperty(key,                     super.cachedProperties.get(key));                 else                     call.setScopedProperty(key,                     super.cachedProperties.get(key));             }             // All the type mapping information is             //registered             // when the first call is made.             // The type mapping information is actually             //registered in             // the TypeMappingRegistry of the service,             //which             // is the reason why registration is only             //needed for the first call.             synchronized (this) {                 if (firstCall()) {                     // must set encoding style before                     //registering serializers                call.setEncodingStyle               (org.apache.axis.Constants.URI_SOAP11_ENC);                     for (int i = 0; i <                          cachedSerFactories.size(); ++i) {                         Class cls = (Class)                         cachedSerClasses.get(i);                         javax.xml.namespace.QName qName =                         (javax.xml.namespace.QName)                         cachedSerQNames.get(i);                         Class sf = (Class)                         cachedSerFactories.get(i);                         Class df = (Class)                         cachedDeserFactories.get(i);                         call.registerTypeMapping                        (cls, qName, sf, df, false);                     }                 }             }             return call;         }         catch (Throwable t) {             throw new org.apache.axis.AxisFault            ("Failure trying to get the Call object", t);         }     } more and more lines of code ... }

The last example code was cut short for a very good reason. You don’t really need to know what the code is doing, much like you don’t need to worry about the proxy code in .NET.

Once the Java files are created, compile them with the following command within the localhost directory:

   javac *.java

This should make all the corresponding class files and compile without error. Now the classes are available to any client you wish to create. The following example utilizes these classes.

The import statement brings in all the classes that WSDL2Java created and you compiled. Then the class getSimpleStockWSDL is created with a main method. The result variable is defined so it handles a value returned by the method. Next, the code creates the object myService, which contains information about where the object and method you need to call reside. The next step creates the object mySOAP, which is the actual object that represents the SimpleStockQuote class. Notice that the next step is the mySOAP object calling the getTestQuote method. Then the value of result is output. This piece of code is the simplest call to a Java Web Service shown in this book so far.

    import localhost.*;     public class getSimpleStockWSDL {         public static void main(String [] args) throws         Exception {          //The type the service returns.          double result;          SimpleStockExampleServiceLocator myService =          new  SimpleStockExampleServiceLocator();           localhost.SimpleStockExample mySOAP =          myService.getSimpleStockExample();           result = mySOAP.getTestQuote("C");          System.out.println         ("This is the value: " + result);         }       }

Doesn’t this seem a little like using the WSDL tool found in .NET? It should. Microsoft and IBM collaborated on the WSDL standard, and Apache Axis has its roots as a project that began at IBM. So it’s no wonder that the two processes are similar.

Cross-Platform Web Services Using C# and Java
Cross-Platform Web Services Using C# & JAVA (Charles River Media Internet & Web Design)
ISBN: 1584502622
EAN: 2147483647
Year: 2005
Pages: 128 © 2008-2017.
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