Introdução à Tecnologia de Web-Services

Transcrição

1 Evolução das Tecnologias de Computação Distribuída Introdução à Tecnologia de Web-Services Máquina A Java, VB, Java CVC++ C++,... Request Response Java CORBA RPC Interface IDL Máquina B C++, VB, Java C, CVC++ Java Base de Dados Sistemas Informáticos I, Microsoft Sockets Java Sun CORBA RPC RMI TCP/IP DCOM Modelo Request-Response: Modelo típico das aplicações Client/Server Tecnologias Web CORBA or Java RMI over the Internet? Servlets JSPs ASP CGI Web Server Base de Dados Empresa A Máquina A Firewall Request Response Firewall Máquina B Empresa B Base de Dados HTTP Microsoft CORBA/ Sockets Java Sun RPC JavaRMI TCP/IP DCOM HTML Port 80 is OK... So, use HTTP... 1

2 Intranet Technologies RMI, CORBA, DCOM, MOM,... All these technologies provide App2App interaction within a trusted intranet. And without concern about interoperability between different implementations. Integrar uma Aplicação Java com outra Aplicação Microsoft.NET Máquina A Request Response Máquina B C#.NET Java J2EE Base de Dados Oh Oh, we are playing a difficult game... Some Reasonings... Use HTTP as a transport protocol. (no more connectivity problems...) Represent data as text XML Use Web Technologies to integrate applications (Ex: Web-Server + Servlets) XML Structured way to represent data. It is platform neutral and provides portable, platform independent data. XML provides a meta-language in which we can use specialized languages. 2

3 SOAP SOAP: Simple Object Access Protocol SOAP was initially proposed by Microsoft, Develop Mentor and Userland Software (1998). It is now a standard that defines XML Messages to access remote objects. It can be implemented over HTTP, SMTP or JMS. A SOAP Request Message <SOAP-ENV:Envelope xmlns:soap-env=" " SOAP-ENV:encodingStyle=" "> <SOAP-ENV:Header> <!-- Optional context information --> </SOAP-ENV:Header> <SOAP-ENV:Body> <m:getlasttradeprice <xmlns:m= <tickersymbol>sunw</tickersymbol> </m:getlasttradeprice> </SOAP-ENV:Body> </SOAP-ENV:Envelope> Parâmetro Nome do Web-Service URI do Web- Service A SOAP Response Message <SOAP-ENV:Envelope xmlns:soap-env=" " SOAP-ENV:encodingStyle=" "> <SOAP-ENV:Header> <!-- Optional context information --> </SOAP-ENV:Header> <SOAP-ENV:Body> <m:getlasttradepriceresponse xmlns:m= some_uri"> <price>30.5</price> </m:getlasttradepriceresponse> </SOAP-ENV:Body> </SOAP-ENV:Envelope> Resposta WSDL It is an XML Language for describing Web services, their functions, parameters and return values. Describes what a web service can do, where it resides and how to invoke it. WSDL is essentially the IDL of Web services 3

4 WSDL Basic Protocols <binding name="stockquoteservicebinding" type="stockquoteservicetype"> <soap:binding style="rpc" transport=" <operation name="getquote"> <soap:operation soapaction=" <input> <soap:body type="inmessagerequest" namespace="urn:live-stock-quotes" encoding=" </input> <output> <soap:body type="outmessageresponse" encoding=" </output> </operation> </binding> WSDL SOAP HTTP Service Description XML Messaging Network Protocol What is a Web-Service? A programmable application component that is accessible via standard Internet protocols. Examples: stock quotes, traffic conditions, calculators, news, weather, airplanes checking, web searching,, Goto: Definition Web-Service? Language and platform independent infrastructure for loosely-coupled, inter-operable, app2app communication over the internet. -Separation of specification and implementation -Message-based, synchronous and asynchronous -Standards-based -Using internet protocols -App 2 App 4

5 Web-Services: Protocols Simple Web-Services Transport Protocol: HTTP/HTTPS Data Encoding: SOAP-XML Interface Description: WSDL Service Discovery: UDDI Security: WS-Security, XML-Signature,XML-Encryption Advanced Web-Services Arquitectura Web-Services Service Providers - Create web services and publish them. Service Broker/Registry - Maintains a registry of published services Service Requesters Find the required services by searching the service broker s registry and binding their application to the service provider. 5

6 Integrar uma Aplicação Java com outra Aplicação Microsoft.NET Vantagens dos Web-Services Máquina A Java JDK SOAP Wrapper SOAP Request XML SOAP Response WSDL Description Web services merely serve as the glue between the client and server applications. It is still necessary to use a programming language to design the client and server: Java, C/C++, ASP, C#, VB, PHP, Web- Service Máquina B C#.NET Base de Dados Web services promote interoperability. Web services are based on standards and neutral technologies. Web services solve the connectivity problems between applications. Web services give a new life to legacy applications by making them usable through the Internet. Web-Services against the other technologies?... Web services are complementary to technologies such as J2EE, CORBA,.NET, etc. they do not replace them! They give us a web-friendly tool for system integration: definitely the simplest way to integrate.net, CORBA, J2EE, etc. Desvantagens There is too much hype... Interoperability is currently not fully achieved.. Programming Web-Services is still not an easy task (except in Microsoft.Net). Performance overhead in the communication... 6

7 Some Results Web Services Toolkits 3000 Comparação de tempos (RPC) Microsoft.NET Apache SOAP & AXIS 2500 Sun Microsystems JWSDP Tempo (ms) Sockets RMI JAX-RPC.NET JBOSS IBM WebSphere Bea Weblogic Webmethods Glue Tamanho (bytes) AXIS & Tomcat Programação de Web-Services usando o Apache AXIS 7

8 Instalar Tomcat (v ) Instalar Apache Axis (v 1.3) Instalações... Copiar C:/Axis/webapps/axis C:/Tomcat/webapps/ Axis directories Directory Structure: axis-1_0 Instalar XML API (xercesimpl.jar, xml-apis.jar,...) na directoria Axis/lib e em Tomcat/webapps/axis/WEB-INF/lib/ set CLASSPATH: setenv.bat ou alterar variaveis environment. webapps axis WEB-INF lib docs samples set AXIS_HOME=C:\axis-1_3 Set CLASSPATH =.;C:\j2sdk1.4.2_02\lib\saaj.jar;C:\j2sdk1.4.2_02\lib\jaxrpc.jar;%AXIS_HOME%\lib\activation.jar; %AXIS_HOME%\lib\mailapi.jar;%AXIS_HOME%\lib\axis.jar;%AXIS_HOME%\lib\axis-ant.jar;%AXIS_HOME%\lib\axisschema.jar;%AXIS_HOME%\lib\activation.jar;%AXIS_HOME%\lib\commons-logging jar; %AXIS_HOME%\lib\commons-discovery-0.2.jar;%AXIS_HOME%\lib\dom.jar;%AXIS_HOME%\lib\jdom.jar; %AXIS_HOME%\lib\jaxp-api.jar;%AXIS_HOME%\lib\jaxrpc.jar;%AXIS_HOME%\lib\saaj.jar; %AXIS_HOME%\lib\sax.jar %AXIS_HOME%\lib\xercesImpl.jar;%AXIS_HOME%\lib\xmlapis.jar;%AXIS_HOME%\lib\wsdl4j jar; %AXIS_HOME%\lib\log4j1.2.8.jar ;%AXIS_HOME%\lib\xsltc.jar;%AXIS_HOME%\lib\xalan.jar; C:\j2sdk1.4.2_02\lib\tools.jar; lib classes web.xml Testar Instalação Ver Config do Tomcat Start Tomcat Testar Tomcat e Axis. Validate Axis

9 Web-Service: Método Imediato Desenvolver o Primeiro Web-Service Escrever uma classe em java. Gravar esse ficheiro com terminação.jws em vez de.java ColocarAddFunction.jws na directoriawebapps/axis Examine a descrição WSDL: Invocar o Web-Service através de um Browser:

10 Desenvolver uma App Cliente 1. Usando DII (Dynamic Invocation Interface) 2. Usando um Dynamic Proxy 3. Usando Stubs (gerados a partir do WSDL) Vamos usar a abordagem dos stubs baseados no WSDL Gerar Stubs a partir do WSDL java org.apache.axis.wsdl.wsdl2java -p ADD STUBS são gerados para a package ADD: -AddFunction -AddFunctionService -AddFunctionServiceLocator -AddFunctionSoapBindingStub SE DER ERRO, VERIFICAR CLASSPATH. INCLUIR TODOS OS JARS no FICHEIRO SETENV.BAT Código do Cliente Compilar e Executar!!" # $ % & '(& ) *&&+,- %)./ &$ #, 01, -1. 2&&'3( 2&&'0( % $ * 2 % $4 567) * 2*& %) %).89 *

11 JWS Deployment JWS Deployment é simples mas tem limitações: É preciso colocar o src no servidor tomcat Compilação na altura da invocação Não suporta acções de personalização Activar o Web-Service no Tomcat/Axis Alternativa: activar um Web-Service usando WSDD Criar um Web-Service # javac Calculator.java put Calculator.class em Tomcat/webapps/axis/WEB-INF/classes (A) Configurar Tomcat: serverconfig.wsdd Se quisermos fazer o deploy manual deste web-service editamos o "server-config.wsdd" do TOMCAT inserindo o seguinte: <service name="calculator" provider="java:rpc"> <parameter name="allowedmethods" value="add subtract"/> <parameter name="scope" value="session"/> <parameter name="classname" value="calculator"/> <parameter name="wsdltargetnamespace" value=" r"/> </service> - Atenção, neste caso, temos que fazer um restart ao Tomcat... 11

12 B: Alternativa (ainda manual) Criar um Ficheiro deploy.wsdd Ficheiro: deploy.wsdd Verificar se o serviço está activo no Axis <deployment xmlns=" xmlns:java=" <service name="calculator" provider="java:rpc"> <parameter name="wsdltargetnamespace" value=" <parameter name="classname" value="calculator"/> <parameter name="allowedmethods" value="add subtract"/> <parameter name="scope" value="session"/> </service> </deployment> e podemos fazer o deploy sem restart do Tomcat (deploy.bat): java org.apache.axis.client.adminclient - lhttp://localhost:8080/axis/services/adminservice deploy.wsdd Verificar o método e parâmetros Testar usando um browser: Desenvolver a App Cliente 12

13 1st Step: Gerar stubs cliente Compile and Run java org.apache.axis.wsdl.wsdl2java -p calc javac *.java java CalculatorClient " ## $ %& &'( #%$4 2 #567) 2 ) 2#%$4 2&# %) %) %).8.&: & %;7 Service: MillionaireQuiz Desenvolver uma App Cliente para um Web-Service externo Ver web-service at: Millionaire Quiz Implemented in GLUE WSDL: 13

14 WSDL: WSDL Analyzer Gerar Stubs, Compilar, Executar Generated Stubs // Generate Stubs java org.apache.axis.wsdl.wsdl2java -p quiz // Compile javac *.java // Run java Client 14

15 ServiceLocator and Stub QuizServiceLocator l = null; IQuizService_PortType stub = null; l = new QuizServiceLocator(); stub = l.getiquizservice(); //IQuizService interface //iquizservice_porttype stub //QuizServiceLocator.getIQuizService() Client import java.io.*; import quiz.*; public class Client{ public static void RandomQuestionAndAnswer() { QuizServiceLocator l = null; IQuizServiceStub_PortType stub = null; MultipleChoiceQuestion mcq = null; try { l = new QuizServiceLocator(); stub = l.getiquizservice(); BufferedReader br = new BufferedReader (new InputStreamReader(System.in)); while(true){ mcq= stub.randomquestion(); System.out.println(mcq.getQuestion()); System.out.println("a: " + mcq.getanswera()); System.out.println("b: " + mcq.getanswerb()); System.out.println("c: " + mcq.getanswerc()); System.out.println("d: " + mcq.getanswerd()); System.out.println("Your choice (a,b,c or d): "); String guessedanswer = br.readline(); System.out.println ( stub.checkcorrectanswerbyid (mcq.getid(),guessedanswer)); System.out.println("======================="); } } catch (Exception e) { System.err.println("Execution failed. Exception: " + e); } } public static void main(string[] args ) { RandomQuestionAndAnswer(); } } Client </AULA WEB-SERVICES> 15