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Tutorial: Writing and Calling Web Services using Java

Methodologies in the Development of Information Systems. Tutorial: Writing and Calling Web Services using Java. Eran Toch November 2004. Agenda. AXIS Introduction Installing Tomcat Installing AXIS Deploying a Web service Running a Client Creating Server and Client Stubs.

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Tutorial: Writing and Calling Web Services using Java

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  1. Methodologies in the Development of Information Systems Tutorial: Writing and Calling Web Services using Java Eran Toch November 2004

  2. Agenda • AXIS Introduction • Installing Tomcat • Installing AXIS • Deploying a Web service • Running a Client • Creating Server and Client Stubs Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  3. Axis Web Services Architecture Client JAX-RPC http port 80 Apache Tomcat AXIS Service Application Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  4. Tomcat Installation • Go to: http://jakarta.apache.org/tomcat/ • Download the latest version (currently 5.5.4) by going to: Downloads -> Binaries -> Tomcat 5.5.4. • For Windows, download the exe version – with a Windows setup. The direct link: http://apache.fresh.co.il/jakarta/tomcat-5/v5.5.4/bin/jakarta-tomcat-5.5.4.exe • For Linux, read the setup manual: http://jakarta.apache.org/tomcat/tomcat-5.5-doc/setup.html Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  5. Tomcat and Java 5 • Please note that Tomcat v. 5.5.4 requires J2SE 1.5 (also known as J2SE 5) or above. • If you want to use J2SE 1.4, download Tomcat 5.0.+ Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  6. Tomcat Installation – cont’d If you want Tomcat to startup every time the computer is rebooted, check the “service” option. If you wish to use Tomcat for only for development, it’s best to leave the service option unchecked. Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  7. Tomcat Installation - Port You can configure the port that Tomcat will be using. If you want it to be available publicly (behind firewalls etc), change the default port to 80. Otherwise, leave it as it is (880). You can always change it later, in the [TOMCAT_HOME]/conf/server.xml configuration file. Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  8. Running Tomcat • Start Tomcat by running Tomcat monitor (Start Menu -> Apache Tomcat -> Monitor Tomcat), and click on Start. • Point your browser to: http://localhost:8080. If Tomcat works, you should see something like this • If not, check out the logs (C:\[TOMCAT_HOME]\logs\stdout) and see what went wrong. Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  9. Managing Tomcat • Go to the management console by clicking on the “management” link in the Tomcat root homepage, or directly by going to: http://localhost:8080/manager/html. • The default username and password are “admin”/””. You can change it by changling the [TOMCAT_HOME]\conf\tomcat-users.xml. Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  10. Managing Tomcat Console Start, stop, restart and undeploy applications Web Application management Number of current sessions Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  11. Apache AXIS • A SOAP Processing Engine • JAX-RPC Client System • JAX-RPC Server System ( Servlet based ) • SAAJ implementation • Flexible and extensible architecture • Tools, Examples, Documentation, … • A great place to learn about Web Services !! • Open-source, hosted by Apache Software Foundation • Packages for Java and C++ Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  12. Download Apache Axis • Make sure that you have • J2SE SDK 1.4 or later • Tomcat • Download latest version (currently 1.1) from http://ws.apache.org/axis/. Direct Link: http://ws.apache.org/axis/download.cgi • For Windows, download the “Binary zip” version. • Unzip it somewhere. Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  13. Deploy Axis • Copy webapps\axis tree to webapps directory of Tomcat. • Alternatively, modify server.xml of Tomcat. • Run, or restart, Tomcat. Direcotry Structure: axis-1_1 webapps lib docs samples axis WEB-INF lib classes web.xml …… Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  14. Test the Deployment • Point your browser to http://localhost:8080/axis, you should see something like this: Click on “Validate” in order to see if the installation went all right Click on “view” to see all the current deployed web services Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  15. Installation problems • For example, if “activation.jar” is missing, • Download it from: http://java.sun.com/products/javabeans/glasgow/jaf.html • Unzip it • Copy “activation.jar” to [TOMCAT_HOME]/webapps/axis/WEB-INF/lib Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  16. Deploy a Web Service Create a Java class using this code: • Name the file AddFunction.jws. Notice the filename extension – it is .jws ( for Java Web Service). Make sure the name of the file is identical to the name of the Java class. • Deploy it by copying the file to webapps/axis/services directory. • That’s it! public class AddFunction { public int addInt(int a, int b){ return (a+b); } } Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  17. The WSDL File • Examine its WSDL description. Point your browser to http://localhost:8080/axis/AddFunction.jws?wsdl - <wsdl:message name="addIntResponse"> <wsdl:part name="addIntReturn" type="xsd:int"/> </wsdl:message> <wsdl:message name="addIntRequest"> <wsdl:part name="a" type="xsd:int"/> <wsdl:part name="b" type="xsd:int"/> </wsdl:message> <wsdl:portType name="AddFunction"> <wsdl:operation name="addInt" parameterOrder="a b"> <wsdl:input message="impl:addIntRequest" name="addIntRequest"/> <wsdl:output message="impl:addIntResponse" name="addIntResponse"/> </wsdl:operation> </wsdl:portType> Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  18. A WSDL document describes What the service can do Where it resides How to invoke it Defines binding for SOAP1.1, HTTP GET/POST and MIME WSDL Refresh WSDL Document [Types] {Messages} {Port Types} {Bindings} {Services} Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  19. Debugging the Service with XMLSpy • In XMLSpy, Click on SOAP -> Create new SOAP request. • Find the WSDL File. • Choose the operation (there is a single one) Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  20. Debugging – cont’d This is how a SOAP message will look like: <SOAP-ENV:…> <SOAP-ENV:Body> <m:addInt xmlns:m=http://DefaultNamespace…> <a xsi:type="xsd:int">0</a> <b xsi:type="xsd:int">0</b> </m:addInt> </SOAP-ENV:Body> </SOAP-ENV:Envelope> Change the default operation values Click on SOAP -> Send Request to Server Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  21. Debugging – cont’d • This is the SOAP message that was returned from the Server <?xml version="1.0" encoding="UTF-8"?> <soapenv:Envelope…> <soapenv:Body> <ns1:addIntResponse…> <ns1:addIntReturn xsi:type="xsd:int">9</ns1:addIntReturn> </ns1:addIntResponse> </soapenv:Body> </soapenv:Envelope> Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  22. Writing the Client Program • There are many ways to write a Client program • Using Dynamic Invocation Interface (DII) • Using generated Stubs from Service WSDL description Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  23. Client – using DII with Eclipse • Create a new Eclipse Java Project • Add all the jars under axis_1-1/lib to the java build path libraries (using external jars) • Create a new class, called “Client” Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  24. Client – using DII import org.apache.axis.client.Service; import org.apache.axis.client.Call; import javax.xml.namespace.QName; public class Client { public static void main(String[] args) { try { String endpoint = "http://localhost:8080/axis/AddFunction.jws"; Service service = new Service(); Call call = (Call) service.createCall(); call.setOperationName(new QName(endpoint, "addInt")); call.setTargetEndpointAddress(new java.net.URL(endpoint)); Integer ret = (Integer) call.invoke(new Object[] { new Integer(5), new Integer(6) }); System.out.println("addInt(5, 6) = " + ret); } catch (Exception e) { System.err.println("Execution failed. Exception: " + e); } } } Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  25. Client - Output addInt(5, 6) = 11 Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  26. Creating Server-Side Stubs • Use the WSDL2Java command: • Make sure that Axis’ jars are on the classpath • Another option is to use Eclipse instead java org.apache.axis.wsdl.WSDL2Java --server-side --skeletonDeploy true SRM.wsdl Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  27. Quick and Dirty: Using Eclipse for Running WSDL2Java • Open a new Java project • Add all the Axis libraries • Configure a Run setting • Check the “Include external jars option” Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  28. Quick and Dirty – con’d Set the arguments: Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  29. Server-side Stubs • The following files will be created: • deploy.wsdd • undeploy.wsdd • SRM.java • SRMService.java • SRMSoapBindingSkeleton.java • CategoryType.java • SRMMessage.java • StaffMemberList.java • SRMServiceLocator.java • SRMSoapBindingImpl.java • SRMSoapBindingStub.java If Eclipse was used, Don’t forget to refresh the project in order to see the files Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  30. Implement Functionality • Change the code of SRMSoapBindingImpl, implementing the operations: public StaffMemberList getStaffMemberList() throws java.rmi.RemoteException { MySRM mySrmApp = new MySRM(); String[] members = mySrmApp.getTAs(); StaffMemberList list = new StaffMemberList(); list.setStaffMemberName(members); return list; } Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  31. Deploy the Service • Copying: • Copy the package (edu.technion…) from where it was created (for instance, C:\eclipse\workspace\SRM-WSDL) to:[TOMCAT-HOME]/webapps/axis/WEB-INF/classes. • It is not important to copy the two wsdd files. • Run the AdminClient program: • deploy.wsdd should be with the full path, of course java org.apache.axis.client.AdminClient deploy.wsdd Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  32. Checking Deployment • Go to http://localhost:8080/axis/servlet/AxisServlet and see that the service is actually deployed. • If not, checkout [TOMCAT-HOME]/logs/stdout for errors. • If the following error occurred, then maybe the classes were not copied correctly - Unable to deploy typemapping: {http://ie.technion.edu/methodologies/srm/}SRMMessage java.lang.ClassNotFoundException: edu.technion.ie.methodologies.srm.SRMMessage Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  33. Creating Client Stubs • Use the WSDL2Java command: • Make sure that Axis’ jars are on the classpath (or use Eclipse instead) java org.apache.axis.wsdl.WSDL2Java SRM.wsdl Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  34. Client Stub Structure • The following files will be created: • SRM.java • SRMService.java • SRMSoapBindingSkeleton.java • CategoryType.java • SRMMessage.java • StaffMemberList.java • SRMServiceLocator.java • SRMSoapBindingStub.java Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

  35. Write a client that uses the Stub package edu.technion.ie.methodologies.srm; import javax.xml.rpc.*; import java.net.MalformedURLException; import java.net.URL; import java.rmi.*; public class SRMClient { public static void main(String[] args) { SRMService srmLocator = new SRMServiceLocator(); try { URL srmUrl = new URL("http://localhost:8080/axis/services/SRM"); SRM service = srmLocator.getSRM(srmUrl); StaffMemberList list = service.getStaffMemberList(); String[] members = list.getStaffMemberName(); for (int i=0; i<members.length; i++) { System.out.println(members[i]); } } catch (MalformedURLException mue) {System.out.println(mue);} catch (ServiceException ex) {System.out.println(ex);} catch (RemoteException rex) {System.out.println(rex);} } } Writing and Calling Web Services using Java – Eran Toch Methodologies in Information System Development

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