Programming and So

Defining one entry point for every web service request in the system can be advisable in specific scenarios such as security based on URL ones. Below it’s described this kind of solution using Spring WS 1.0 as web service stack and XMLBeans 2 as marshalling method.

web.xml

Define desired URL (for instance, http://server/app/services/)

<!-- Defines the Spring-WS MessageDispatcherServlet -->
<servlet>
    </servlet><servlet -name>spring-ws</servlet>
        <servlet -class>
            org.springframework.ws.transport.http.MessageDispatcherServlet
        </servlet>
        <init -param>
            <!-- Transform the location attributes in WSDLs -->
            <param -name>transformWsdlLocations</param>
            <param -value>true</param>
         </init>

<!-- Map all requests to this servlet -->
<servlet -mapping>
    </servlet><servlet -name>spring-ws</servlet>
    <url -pattern>/services/*</url>

applicationContext.xml

Configuration to get XMLObjects from XMLBeans unmarshalled at the endpoint.

<!-- EndPoint Mapping -->
<bean id="messageDispatcher"
    class="org.springframework.ws.server.MessageDispatcher">
    <property name="endpointMappings">
	<list>
                 <ref local="payloadMapping" />
             </list>
    </property>
</bean>

<!-- Payload Mapping -->
<bean id="payloadMapping" class="org.springframework.ws.server.endpoint.mapping.PayloadRootQNameEndpointMapping">
    <property name="defaultEndpoint" ref="uniqueEndpoint" />
    <!-- XSD validation can be specified -->
    <property name="interceptors">
	<list>
                 <ref local="validatingInterceptor" />
             </list>
    </property>
</bean>

<!-- XSD validation -->
<bean id="validatingInterceptor"
class="org.springframework.ws.soap.server.endpoint.interceptor.PayloadValidatingInterceptor">
    <!-- Schemas repository folder -->
    <property name="schemas" value="/WEB-INF/schemas/*.xsd" />
    <property name="validateRequest" value="true" />
    <property name="validateResponse" value="true" />
</bean>

<!-- Unique endpoint -->
<bean id="uniqueEndpoint" class="foo.bar.EndPoint">
    <!-- XMLBeans marshalling (in & out) -->
    <constructor -arg ref="xmlBeansMarshaller" />
</bean>

Endpoint Java Class

package foo.bar;

public class FCEEndPoint extends org.springframework.ws.server.endpoint.AbstractMarshallingPayloadEndpoint {

    public FCEEndPoint(Marshaller marshaller) {
        super(marshaller);
    }

    protected Object invokeInternal(Object requestObject) throws Exception {

        XmlObject in = (XmlObject)requestObject;

        // Retrieve operation name from some point of the incoming XML
        String operationName = in.getDomNode().getFirstChild().getNodeValue();

        // Generic invoker based on Java reflection
        XmlObject out = OperationInvoker.invoke(operationName, in);

        return out;

    }
}

How it works?

In this way, new web services can be added by creating one XSD file and implementing its related business object. And clients only have to invoke the same URL for each request just only by using an appropiate XML.