Modulo II WebServices

1. Modulo II WebServices Prof. Ismael H F Santos Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 1

2. Bibliografia Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 2

3. Ementa • WebServices em Java Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 3

4. SOA WebServices Java Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 4

5. WebServices com Java • A plataforma J2EE oferece as seguintes APIs: • Document-oriented • Java API for XML Processing (JAXP) processes XML documents using various parsers • Java Architecture for XML Binding (JAXB) processes XML documents using schema-derived JavaBeans component classes • Procedure-oriented • Java API for XML-based RPC (JAX-RPC) sends SOAP method calls to remote parties over the Internet and receives the results • Java API for XML Messaging (JAXM) sends SOAP messages over the Internet in a standard way • Java API for XML Registries (JAXR) provides a standard way toaccess business registries and share information Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 5

6. WebServices com Java • A tecnologia Java oferece tambem as seguintes ferramentas: • Java Web Services Developer Pack (Java WSDP) • SOAP with Attachments API for Java (SAAJ) • Com estas APIs você não precisa saber como criar o SOAP. Você só precisa saber utilizar as classes da API para criar e acessar os Web Services. Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 6

7. State of the Art UDDI WSDL SOAP URI HTML HTTP Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 7

8. Components required Software which needs to be exposed as a Web service A SOAP Server (Apache Axis, SOAP::Lite, etc.) HTTP Server (if HTTP is used as the transport level protocol) SOAP Client (Apache Axis, SOAP::Lite etc.) Web Service : How They Work? SOAP Messages Requestor (http transport) SOAP Client Endpoint Web Service Provider Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 8

9. Service Requestor Remote Web Service Repository (Web Sites) 2 Manual Web Service Lookup HTTP GET 3 WSDL File Write Client Code 1 Remote Web service 4 SOAP Request Invoke Web Service Publish Web Service 5 SOAP Response WSDL - Web Service Description SOAP - Web Service Message Protocol Simple Web Service Invocation Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 9

10. Web Service Description • Why describe Web services? • A service requestor needs to analyze a service for his requirements • A Web service needs to provide the following information • the operations it supports • the transport and messaging protocols on which it supports those operations • the network endpoint of the Web service • Languages such as WSDL, DAML-S, RDF can be used for describing Web services • WSDL – describes the syntactic information of a service • DAML-S and RDF – describe the syntactic as well as the semantic information From S. Chandrasekaran’s Talk Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 10

11. Web Service Description (WSDL) Abstract Description Concrete Description Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 11

12. SOA WebService Example Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 12

13. HTTP Server Servlet engine (e.g. Apache Tomcat) Any class processing the incoming requests (“business logic” Any class processing the incoming requests (“business logic” Any class processing the incoming requests (“business logic” Any class processing the incoming requests (“business logic” SOAP-aware Servlet (e.g. Apache Axis) Sending requests, getting results A Web Service example in Java Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 13

14. Usual principles of Java toolkits • Writing server is easier than writing clients (but only regarding the toolkit, not the business logic) • Servers may be written independently on the used toolkit • Always test interoperability with a non-Java client (because of data serialization and de-serialization) • Steps: • write your service implementation • make all your classes available to the toolkit • deploy your service (usually done just once) • restart the whole servlet engine • test it with a client request Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 14

15. Java SOAP Toolkits • Apache SOAP (was IBM’s SOAP4J) • Apache Axis (a follow-on to the Apache SOAP) • http://ws.apache.org/axis/ • …and many others Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 15

16. hello/HelloWorld.java package hello; public interface HelloWorld { String getHelloMessage(); void setHelloMessage (String newHello); } hello/HelloWorldService.java package hello; public class HelloWorldService implements HelloWorld { String message = "Hello, world!"; public String getHelloMessage() { return message; } public void setHelloMessage (String newMessage) { message = newMessage; } } Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 16

17. HelloWorldClient.java import org.apache.axis.client.*; public class HelloWorldClient { public static void main (String [] args) { try { // prepare the call (the same for all called methods) Call call = (Call) new Service().createCall(); call.setTargetEndpointAddress (new java.net.URL( "http://localhost:8080/axis/services/Hello")); // call "get message" if (args.length == 0) { call.setOperationName ("getHelloMessage"); String result = (String)call.invoke( new Object[]{} ); System.out.println (result); System.exit (0); } Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 17

18. HelloWorldClient.java // call "set message" and afterwards "get message" call.setMaintainSession (true); // TRY also without // this line... call.setOperationName ("setHelloMessage"); call.invoke ( new Object [] { args[0] } ); call.setOperationName ("getHelloMessage"); System.out.println (call.invoke ( new Object [] {} )); } catch (Exception e) { System.err.println ("ERROR:\n" + e.toString()); } } } Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 18

19. 1. Make an instance of this HelloWorldService HelloWorld implements implements 2. Use it to make an instance of this HelloWorldServiceLocator HelloSoapBindingStub 3. Call methods on this proxy object Generated for HelloWorld getHello() Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 19

20. HelloWorldClientFromStubs.java public class HelloWorldClientFromStubs { public static void main (String [] args) { try { // prepare the calls (the same for all called methods) hello.generated.HelloWorldService service = new hello.generated.HelloWorldServiceLocator(); hello.generated.HelloWorld myHelloProxy = service.getHello(); // call "get message" if (args.length == 0) { String result = myHelloProxy.getHelloMessage() System.out.println (result); System.exit (0); } // call "set message" and afterwards "get message” myHelloProxy.setHelloMessage (args[0]); System.out.println (myHelloProxy.getHelloMessage()); } catch (Exception e) { System.err.println ("ERROR:\n" + e.toString()); } } } Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 20

21. Java <=> XML Data Mapping • How Java objects are converted to/from XML data (in order to be able to be put into SOAP messages) • Important especially for the non-basic data types • It’s easier if your non-basic data types are Java Beans (having set/get methods for members) Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 21

22. Examples (Java Client) URL endpointURL = new URL(endpoint); Call call = new Call(); call.setSOAPTransport(m_httpconn); call.setTargetObjectURI("MessageService"); call.setMethodName("setMessage"); call.setEncodingStyleURI(Constants.NS_URI_SOAP_ENC); Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 22

23. Examples (Java Client) Vector params = new Vector(); params.addElement( new Parameter("name", java.lang.String.class, name, null)); params.addElement( new Parameter("colour", java.lang.String.class, colour, null)); call.setParams(params); Response response = call.invoke(endpointURL, ""); Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 23

24. package HelloPerl; use strict; use vars qw( $Message ); $Message = 'Hello, here is Perl.'; sub getHelloMessage { $Message; } sub setHelloMessage { $Message = shift; } 1; This is a module implementing the “business logic” This is a client #!/usr/bin/perl –w use SOAP::Lite on_fault => sub {…}; print SOAP::Lite -> uri ('HelloPerl') -> proxy ('http://localhost/cgi-bin/helloserver.cgi') -> getHelloMessage -> result; A Web Service example in Perl #!/usr/bin/perl -w -- Perl – use SOAP::Transport::HTTP; SOAP::Transport::HTTP::CGI -> dispatch_to('HelloPerl') -> handle; This is a cgi-bin script Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 24

25. SOAP::Lite • a collection of (many) modules • but they are loaded automatically when needed • supports SOAP 1.1 specification • all methods can be used for both setting and retrieving values: • if you provide no parameters, you will get current value, and if parameters are provided, a new value will be assigned to the object • and the method in question will return the current object (if not stated otherwise) which is is suitable for stacking these calls like: $lite = SOAP::Lite -> uri(’openBQS') -> proxy('http://industry.ebi.ac.uk/soap/openBQS'); Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 25

26. Using “wsdl” - directly • getting “.wsdl” file by using its URL • then, you do not need to worry about autotyping #!/usr/bin/perl -w use SOAP::Lite on_fault => sub {…}; print SOAP::Lite -> service ('file:/home/senger/ws-ws/perl/Hello.wsdl') -> setHelloMessage (123); #!/usr/bin/perl -w use SOAP::Lite on_fault => sub {…}; my $service = SOAP::Lite -> service ('file:./Hello.wsdl'); $service->setHelloMessage ($ARGV[0] or "Hello!!!"); print $service->getHelloMessage, "\n"; Prof. Ismael H. F. Santos - ismael@tecgraf.puc-rio.br 26