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System.out.println("Type of file 'file.txt' is " + ret); } catch (Exception e) { System.err.println(e.toString()); } } } There are other ways of achieving the same result, but this is good enough for the rest of this chapter, which is intended to show how Jini and Web Services can interoperate rather than delve into the arcanities of Web Services.

A bridge that acts as a Jini service implementing the common.FileClassifier specification used throughout this book, and also as a client to the previous file classification Web Service, can be written by essentially including the Web Service client code from earlier into the implementation of the Jini service methods. The bridge is a normal Jini server advertising the following Jini service implementation: package ws; import common.MIMEType; import common.FileClassifier; import org.apache.axis.client.Call; import org.apache.axis.client.Service; import javax.xml.namespace.QName; /** * FileClassifierImpl.java */ public class FileClassifierImpl implements RemoteFileClassifier { public MIMEType getMIMEType(String fileName) throws java.rmi.RemoteException { try { String endpoint = "http://localhost:8080/axis/FileClassifierService.jws"; Service Call service = new Service(); call = (Call) service.createCall();

call.setTargetEndpointAddress( new java.net.URL(endpoint) ); call.setOperationName(new QName("http://soapinterop.org/", "getMIMEType")); String ret = (String) call.invoke( new Object[] { fileName } ); return new MIMEType(ret); } catch (Exception e) {

throw new RemoteException("SOAP failure", e); } } public FileClassifierImpl() throws java.rmi.RemoteException { // empty constructor required by RMI } } // FileClassifierImpl This service can export a Jeri or RMI proxy to a Jini client as we have seen before. Client calls on the proxy are sent to this service, which acts as a Web Service client using the model of Figure 28-2. When this implementation is built and run, it will need the Axis libraries on the Jini service side.

A service can be written that follows the second pattern in Figure 28-3, simply by changing the inheritance from RemoteFileClassifier to FileClassifier and Serializable. A client then gets a copy of this service and all calls are made locally in the client. package ws; import common.MIMEType; import common.FileClassifier; import org.apache.axis.client.Call; import org.apache.axis.client.Service; import javax.xml.namespace.QName; /** * FileClassifierImpl.java */ public class FileClassifierSerializableImpl implements FileClassifier, java.io.Serializable { public MIMEType getMIMEType(String fileName) throws java.rmi.RemoteException { try { String endpoint = "http://localhost:8080/axis/FileClassifierService.jws"; Service Call service = new Service(); call = (Call) service.createCall();

call.setTargetEndpointAddress( new java.net.URL(endpoint) ); call.setOperationName(new QName("http://soapinterop.org/", "getMIMEType"));

String ret = (String) call.invoke( new Object[] { fileName } ); return new MIMEType(ret); } catch (Exception e) { throw new RemoteException(e); } } public FileClassifierImpl() throws java.rmi.RemoteException { // empty constructor required by RMI } } // FileClassifierImpl This has major implications for the classes downloaded to the client! In order to run this service on the client side, it needs access to the class files for the Axis classes Call, Service, and QName. The client cannot be expected to have these, since it doesn t need to know any details of the implementation. So the Axis libraries have to be placed on an HTTP server and listed in the Jini server s codebase. The libraries are over 1MB in size, so needing to send these across the network can result in a substantial download to the Jini client.

Forming a bridge between Web Service clients and Jini services follows the same general structure, as shown in Figure 28-4.

Figure 28-4. Bridge between a Web Service client and a Jini service In this case, we put the Jini client code into the Web Service implementation. There are a couple of wrinkles in getting this to work properly with Apache Axis and the Tomcat server: Jini class files Security policy The Jini class files are not in the classpath for Tomcat. However, Tomcat and Apache allow any extra .jar files required by a Web Service to be placed in special lib directories under the