Bare JAX-WS

Java API for XML - Web Services (JAX-WS) is a specification [3] that addresses Java web services development. For web service clients, this amounts to generating Java client service stubs and XML bindings for use in invoking the web service. Figure 1 illustrates how these components fit together. The green and yellow components are generated from the WSDL. The green is the service stub. Its objects make the remote call to the service provider. The yellow represents the XML-type-to-Java-type bindings (or simply XML bindings). The XML bindings are actually addressed by a separate specification called Java API for XML Bindings (JAXB) that is referenced by JAX-WS. This is part of what makes JAX-WS so much more powerful than its predecessor, Java API for XML - Remote Procedure Call (JAX-RPC).

Figure 1. JAX-WS Overview

Another recent improvement is the inclusion of the JAX-WS runtime in the Java 6 SE (standard edition). One no longer needs to reference special "thin client" libraries to make web service clients run. The generated bindings run directly against a Java 6 or later runtime. And not only are the runtime classes available in the JRE, the wsimport utility, responsible for generating the bindings from the WSDL, is part of the JDK on any platform. No special IDEs or tools are needed.

The XML bindings are Java classes that map to the XML schema types defined in the WSDL. (One says that a Java type is bound to the XML schema type.) These types play the role of parameters for the service invocation. The invocation functions themselves are methods on the service stub objects. The bindings objects are passed as parameters to the service objects.

The generated service and binding objects tie into the JAX-WS runtime. This may be part of the JDK as in the diagram above. Or it may be implemented by a vendor such as Apache CXF or IBM WebSphere Application Server. In any case, it is responsible for

Finally, the client code is the consumer of the service. It issues the request to the service stub and does whatever it requires with the result.

Web service clients may be managed or unmanaged. Managed clients are typically associated with an application server. The client is managed in the sense that aspects of its configuration are controllable through the administrative capabilities of the application server. References to the service stub objects are usually retrieved from JNDI. Unmanaged clients, also known as thin clients, do not rely on any underlying application server structure for configuration. Their service client proxy objects are directly instantiated. Their configuration is usually done by setting properties on the service stub instances. There is nothing wrong with running a thin client inside an application server. It simply won't benefit from enterprise manageability features.

A thin client is one that does not expect the presense of any application server infrastructure. That's not to say a thin client can't run within an application server container. It simply doesn't depend on the container for resources or initialization.

Generating a thin client is easy and requires nothing more than a valid WSDL and JDK 6. The command for generating the JAX-WS bindings is wsimport. It should be in your command line path so long as your JDK is. To verify its version and presence in your path, query its version.

$ wsimport -version
JAX-WS RI 2.1.6 in JDK 6
$

We'll use the WSDL listed in Section 2.1. It's a standalone WSDL file with a single operation that queries information about a credit card account. Let's start with the following invocation of wsimport.

thinclient$ wsimport -d bin -s src -p org.acme.cc.jaxws ccQuery.wsdl
parsing WSDL...
generating code...
compiling code...
thinclient$

The options have the following meanings.

If you run this command without first creating the bin and src directories, the command will give an error. Otherwise you get the following generated bindings classes.

thinclient/src/org/acme/cc/jaxws$ ls -l
total 64
-rw-r--r--  1 pglezen  staff  1073 Jun 16 13:42 CCPortType.java
-rw-r--r--  1 pglezen  staff  2341 Jun 16 13:42 CCService.java
-rw-r--r--  1 pglezen  staff  1363 Jun 16 13:42 ObjectFactory.java
-rw-r--r--  1 pglezen  staff  1813 Jun 16 13:42 QueryFault.java
-rw-r--r--  1 pglezen  staff  1053 Jun 16 13:42 QueryFaultMsg.java
-rw-r--r--  1 pglezen  staff  2061 Jun 16 13:42 QueryRequest.java
-rw-r--r--  1 pglezen  staff  3727 Jun 16 13:42 QueryResponse.java
-rw-r--r--  1 pglezen  staff   108 Jun 16 13:42 package-info.java
thinclient/src/org/acme/cc/jaxws$ 

The problem with this generation of bindings concerns the CCService class. It needs to find a copy of the WSDL and without any additional arguments to wsimport, it uses the fully-qualified path name to the WSDL file from which the bindings were generated.

URL baseUrl;
baseUrl = org.acme.cc.jaxws.CCService.class.getResource(".");
url = new URL(baseUrl, "file:/Users/pglezen/thinclient/ccQuery.wsdl");

Clearly we don't want code referencing an absolute path on a developer's workstation. We provide information to wsimport via the -wsdllocation. From the code snippet above, one can see that the base of the URL begins with the package directory of the class itself. The WSDL will be found if we add it to the directory holding CCService.java.

thinclient$ wsimport -d bin -s src -p org.acme.cc.jaxws -wsdllocation ccQuery.wsdl ccQuery.wsdl

This results in the following snippet in CCService.java.

URL baseUrl;
baseUrl = org.acme.cc.jaxws.CCService.class.getResource(".");
url = new URL(baseUrl, "ccQuery.wsdl");

But then we have to make sure to copy the WSDL file to the source directory where CCService.java resides. An alternative is to count the directory levels between CCService.java (four in this case) and specify this to the wsimport. Then we can simply copy the WSDL to the bin directory.

thinclient$ wsimport -d bin -s src -p org.acme.cc.jaxws
            -wsdllocation ../../../../ccQuery.wsdl ccQuery.wsdl

This result in the following snippet in CCService.java.

try {
  URL baseUrl;
  baseUrl = org.acme.cc.jaxws.CCService.class.getResource(".");
  url = new URL(baseUrl, "../../../../ccQuery.wsdl");
} catch (MalformedURLException e) {
  logger.warning("Failed to create URL for the wsdl 
          Location: '../../../../ccQuery.wsdl', retrying as a local file");
  logger.warning(e.getMessage());
}

It makes for a funny-looking warning message if the WSDL is not found. The lesser evil is probably a matter of choice.

The final step is a main method to drive everything. An example is shown in Example 1. If Main.java is in the current directory, it may be compiled as shown below.

pglezen:~/thinclient$ ls
Main.java bin/    ccQuery.wsdl  src/
pglezen:~/thinclient$ javac -d bin -classpath bin Main.java
pglezen:~/thinclient$ 

The -d option tells javac the root directory in which to place the class files. By putting it relative to bin directory, it will be placed with the bindings. Since the Main class references the bindings, and the bindings have already been compiled into the bin directory, it is all that's needed for the -classpath option.

package org.acme.cc.client;

import java.util.Map;

import javax.xml.ws.BindingProvider;

import org.acme.cc.jaxws.CCService;
import org.acme.cc.jaxws.CCPortType;
import org.acme.cc.jaxws.QueryRequest;
import org.acme.cc.jaxws.QueryResponse;
import org.acme.cc.jaxws.QueryFaultMsg;

public class Main {

   public static void main(String[] args) {
      String endpointUrl = "http://localhost:9080/cc/CCService";
      if (args.length == 1) {
         endpointUrl = args[0];
      }
      System.out.println("Using endpoint URL " + endpointUrl);
      CCService service = new CCService();  
      CCPortType port = service.getCCPort();  
      BindingProvider bp = (BindingProvider)port;  
      Map<String, Object> reqCtx = bp.getRequestContext();
      reqCtx.put("javax.xml.ws.service.endpoint.address", endpointUrl);
      
      QueryRequest request = new QueryRequest();
      request.setCcNo("2982-3929-5122-4829");
      request.setLastName("Brown");
      
      QueryResponse response = null;

      try {
         response = port.query(request);  
      System.out.println("Remote method returned.");
      } catch (QueryFaultMsg fault) {
         System.out.println("Caught service exception.");
         System.out.println("\tmsg = " + fault);
      }
      if (response != null) {
         System.out.println("Got response.");
         System.out.println("Account Num = " + response.getAcctNo());
         System.out.println(" First name = " + response.getFirstName());
         System.out.println("    Balance = " + response.getBalance());
      }
   }
}

The javax.xml.ws.BindingProvider interface is key to the ability to dynamically set the remot endpoint. This and other capabitlities are described in Section 4.2.1 on the JAX-WS 2.1 specification [3]. Figure 2 comes from the JAX-WS 2.1 specification. It illustrates the relationship between the BindingProvider and the request context.

Figure 2. JAX-WS Binding Provider

   @Resource(name="MockCC", description="Stub the remote CC call")
   Boolean mockCC = false;
   
   @WebServiceRef(name="jaxwsCC") CCService ccService;
   CCPortType account = null;

   @PostConstruct
   void initDelegate() {
      log.entering(CLASSNAME, "initDelegate");
      if (mockCC) {
         log.warning("Mock is set to true. Using mock imlementation of delegate.");
         account = new AccountQueryMock();
         log.fine("AccountQueryMock instance created.");
      } else {
         account = ccService.getCCService();
         log.fine("AccountQueryDelegate instance created.");
      }
      log.exiting(CLASSNAME, "initDelegate");
   }

JAX-WS XML bindings for the server are no different than they are for the client. When using wsimport from the command line, there is no difference in the appearance of the output. The difference is what you do with the output. You can start by deleting the port type and service classes (the classes by annotations and of Example 1). These would only be used by a client and we're implementing the provider. But this begs the question: what do we use for the implementation class?

The answer, when using wsimport from the command line, is that there is nothing to help you with the implementation class. You just create one from scratch that matches the operations in the WSDL and use Java annotations to piece everything together. The implementation class doesn't even have to implement the service interface! This may seem a bit scary at first. But it's not hard once you know which annotations to use; and we'll get to that in a bit.

The good news for RAD (Rational Application Developer) users is that the Generate Java Bean Skeleton wizard actually does generate the skeleton with the annotations. It is this wizard that we'll discuss in detail for the provider implementation.

package org.acme.cc.jaxws;

@javax.jws.WebService (endpointInterface="org.acme.cc.jaxws.CCPortType", 
                       targetNamespace="urn:issw:bare:wssec:cc:query", 
                       serviceName="CCService", 
                       portName="CCService", 
                       wsdlLocation="WEB-INF/wsdl/ccQuery.wsdl")
public class CCSoapBindingImpl{

    public QueryResponse query(QueryRequest parameters) throws QueryFaultMsg {
        // TODO Auto-generated method stub
        return null;
    }
}

  1 <?xml version="1.0" encoding="UTF-8"?>
    <wsdl:definitions targetNamespace="urn:issw:bare:wssec:cc:query" 
                            xmlns:tns="urn:issw:bare:wssec:cc:query" 
                            xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" 
  5                         xmlns:wsdlsoap="http://schemas.xmlsoap.org/wsdl/soap/" 
                            xmlns:xsd="http://www.w3.org/2001/XMLSchema">
      <wsdl:types>
        <schema targetNamespace="urn:issw:bare:wssec:cc:query" 
                xmlns="http://www.w3.org/2001/XMLSchema">
 10       <element name="QueryRequest">
            <complexType>
              <sequence>
                <element name="ccNo"     type="xsd:string"/>
                <element name="lastName" type="xsd:string"/>
 15           </sequence>
            </complexType>
          </element>
          <element name="QueryResponse">
            <complexType>
 20           <sequence>
                <element name="ccNo"      type="string"/>
                <element name="acctNo"    type="string"/>
                <element name="lastName"  type="string"/>
                <element name="firstName" type="string"/>
 25             <element name="balance"   type="int"/>
              </sequence>
            </complexType>
          </element>
          <element name="QueryFault">
 30         <complexType>
              <sequence>
                <element name="ccNo"  type="string"/>
                <element name="txnId" type="int"/>
              </sequence>
 35         </complexType>
          </element>
        </schema>
      </wsdl:types>
    
 40   <wsdl:message name="QueryRequestMsg">
        <wsdl:part element="tns:QueryRequest" name="parameters"/>
      </wsdl:message>
    
      <wsdl:message name="QueryResponseMsg">
 45     <wsdl:part element="tns:QueryResponse" name="parameters"/>
      </wsdl:message>
    
      <wsdl:message name="QueryFaultMsg">
        <wsdl:part element="tns:QueryFault" name="parameters"/>
 50   </wsdl:message>
    
      <wsdl:portType name="CCPortType">
        <wsdl:operation name="query">
           <wsdl:input  message="tns:QueryRequestMsg"  name="queryRequest"/>
 55        <wsdl:output message="tns:QueryResponseMsg" name="queryResponse"/>
           <wsdl:fault  message="tns:QueryFaultMsg"    name="queryFault"/>
        </wsdl:operation>
      </wsdl:portType>
    
 60   <wsdl:binding name="CCSoapBinding" type="tns:CCPortType">
        <wsdlsoap:binding style="document" transport="http://schemas.xmlsoap.org/soap/http"/>
        <wsdl:operation name="query">
          <wsdlsoap:operation soapAction="ccQuery" style="document"/>
    
 65       <wsdl:input name="queryRequest">
            <wsdlsoap:body use="literal"/>
          </wsdl:input>
    
          <wsdl:output name="queryResponse">
 70         <wsdlsoap:body use="literal"/>
          </wsdl:output>
    
          <wsdl:fault name="queryFault">
            <wsdlsoap:fault name="queryFault" use="literal"/>
 75       </wsdl:fault>
        </wsdl:operation>
      </wsdl:binding>
    
      <wsdl:service name="CCService">
 80     <wsdl:port binding="tns:CCSoapBinding" name="CCPort">
          <wsdlsoap:address location="http://localhost/services/statement"/>
        </wsdl:port>
      </wsdl:service>
    </wsdl:definitions>
 85 

  1 package org.acme.cc.ejb;
    
    import java.util.logging.Logger;
    
  5 import javax.annotation.PostConstruct;
    import javax.annotation.Resource;
    import javax.ejb.LocalBean;
    import javax.ejb.Stateless;
    import javax.xml.ws.WebServiceRef;
 10 
    import org.acme.cc.delegate.AccountQuery;
    import org.acme.cc.delegate.AccountQueryDelegate;
    import org.acme.cc.jaxws.CCPortType;
    import org.acme.cc.jaxws.CCService;
 15 import org.acme.cc.jaxws.QueryFaultMsg;
    import org.acme.cc.jaxws.QueryRequest;
    import org.acme.cc.jaxws.QueryResponse;
    
    @Stateless
 20 @LocalBean
    public class AccountQueryEJB {
       
       public static final String CLASSNAME = AccountQueryEJB.class.getName();
       private static final Logger log = Logger.getLogger(CLASSNAME);
 25    
       @Resource(name="MockCC", description="Stub the remote CC call")
       Boolean mockCC = false;
       
       @WebServiceRef(name="jaxwsCC") CCService ccService;
 30    CCPortType account = null;
    
       public AccountQueryEJB() {
          log.entering(CLASSNAME, "ctor");
          log.exiting(CLASSNAME, "ctor");
 35    }
       
       @PostConstruct
       void initDelegate() {
          log.entering(CLASSNAME, "initDelegate");
 40       if (mockCC) {
             log.warning("Mock is set to true. Using mock imlementation of delegate.");
             account = new AccountQueryMock();
             log.fine("AccountQueryMock instance created.");
          } else {
 45          account = ccService.getCCService();
             log.fine("AccountQueryDelegate instance created.");
          }
          log.exiting(CLASSNAME, "initDelegate");
       }
 50    
       public QueryResponse query(QueryRequest request) throws QueryFaultMsg {
          log.entering(CLASSNAME, "query");
          QueryResponse response = account.query(request);
          log.exiting(CLASSNAME, "query");
 55       return response;
       }
    }