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April 05 Prof. Ismael H. F. Santos - [email protected] 1
Modulo II WebServices
Prof. Ismael H F Santos
April 05 Prof. Ismael H. F. Santos - [email protected] 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
April 05 Prof. Ismael H. F. Santos - [email protected] 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.
April 05 Prof. Ismael H. F. Santos - [email protected] 7
URI HTML HTTP
UDDI WSDL SOAP
State of the Art
April 05 Prof. Ismael H. F. Santos - [email protected] 8
Web Service : How They Work?
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.)
(http transport)Requestor
SOAP Messages
Web Service ProviderEndpoint
SOAP Client
April 05 Prof. Ismael H. F. Santos - [email protected] 9
RemoteWeb ServiceRepository(Web Sites)
WriteClient Code
Service Requestor
Invoke Web Service
Manual Web Service
Lookup
SOAP Request
SOAP Response
WSDL - Web Service DescriptionSOAP - Web Service Message Protocol
WSDL File
Remote Web service
Publish Web Service
1
2
3
4
5
HTTP GET
Simple Web Service Invocation
April 05 Prof. Ismael H. F. Santos - [email protected] 10
From S. Chandrasekaran’s Talk
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
April 05 Prof. Ismael H. F. Santos - [email protected] 11
Web Service Description (WSDL)
Abstract Description
ConcreteDescription
April 05 Prof. Ismael H. F. Santos - [email protected] 13
A Web Service example in Java
SOAP-awareSOAP-awareServletServlet
(e.g. Apache Axis)(e.g. Apache Axis)
SOAP-awareSOAP-awareServletServlet
(e.g. Apache Axis)(e.g. Apache Axis)
Any classprocessing
the incomingrequests
(“business logic”
Any classprocessing
the incomingrequests
(“business logic”
Any classprocessing
the incomingrequests
(“business logic”
Any classprocessing
the incomingrequests
(“business logic”
Any classprocessing
the incomingrequests
(“business logic”
Any classprocessing
the incomingrequests
(“business logic”
Any classAny classprocessingprocessing
the incomingthe incomingrequestsrequests
(“business logic”(“business logic”
Any classAny classprocessingprocessing
the incomingthe incomingrequestsrequests
(“business logic”(“business logic”
HTTP ServerHTTP Server
Servlet engine (e.g. Apache Tomcat)Servlet engine (e.g. Apache Tomcat)
Sending requests,
getting results
Sending requests,
getting results
April 05 Prof. Ismael H. F. Santos - [email protected] 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
April 05 Prof. Ismael H. F. Santos - [email protected] 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
April 05 Prof. Ismael H. F. Santos - [email protected] 16
package hello;public interface HelloWorld {
String getHelloMessage();void setHelloMessage (String newHello);
}
hello/HelloWorld.java
package hello;public class HelloWorldService implements HelloWorld { String message = "Hello, world!"; public String getHelloMessage() {
return message; } public void setHelloMessage (String newMessage) {
message = newMessage; }}
hello/HelloWorldService.java
April 05 Prof. Ismael H. F. Santos - [email protected] 17
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); }
HelloWorldClient.java
April 05 Prof. Ismael H. F. Santos - [email protected] 18
// 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()); } }}
HelloWorldClient.java
April 05 Prof. Ismael H. F. Santos - [email protected] 19
Generated for HelloWorld
HelloWorldServiceLocator
implements
HelloWorldService
getHello()
1. Make an instance of this
3. Call methods on this proxy object
HelloSoapBindingStub
implements
HelloWorld
2. Use it to make an instance of this
April 05 Prof. Ismael H. F. Santos - [email protected] 20
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());
}
}
}
HelloWorldClientFromStubs.java
April 05 Prof. Ismael H. F. Santos - [email protected] 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)
April 05 Prof. Ismael H. F. Santos - [email protected] 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);
April 05 Prof. Ismael H. F. Santos - [email protected] 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, "");
April 05 Prof. Ismael H. F. Santos - [email protected] 24
A Web Service example in Perl
This is a module implementingthe “business logic”
package HelloPerl;use strict;use vars qw( $Message );$Message = 'Hello, here is Perl.';sub getHelloMessage { $Message; }sub setHelloMessage { $Message = shift; }1;
This is a cgi-binscript
#!/usr/bin/perl -w -- Perl –use SOAP::Transport::HTTP;SOAP::Transport::HTTP::CGI -> dispatch_to('HelloPerl') -> handle;
#!/usr/bin/perl –wuse SOAP::Lite on_fault => sub {…};print SOAP::Lite -> uri ('HelloPerl') -> proxy ('http://localhost/cgi-bin/helloserver.cgi') -> getHelloMessage -> result;
This is a client
April 05 Prof. Ismael H. F. Santos - [email protected] 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');
April 05 Prof. Ismael H. F. Santos - [email protected] 26
Using “wsdl” - directly
#!/usr/bin/perl -w
use SOAP::Lite on_fault => sub {…};print SOAP::Lite -> service ('file:/home/senger/ws-ws/perl/Hello.wsdl') -> setHelloMessage (123);
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 {…};my $service = SOAP::Lite -> service ('file:./Hello.wsdl');$service->setHelloMessage ($ARGV[0] or "Hello!!!");print $service->getHelloMessage, "\n";