WEB SERVICES. Sam Guinea

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WEB SERVICES

Sam Guinea

guinea@elet.polimi.it

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Reference Book

Martin Kalin

Java Web Services: Up and Running, 1st Edition

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JAX-WS

•  Java API for XML-Web Services

•  The reference framework for Java Web Services

•  Bundled into the Metro Web Services Stack

•  Part of the Glassfish Application Server but…

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@WebService

@WebService(targetNamespace = "http://duke.org", name="AddNumbers")

public interface AddNumbersIF extends Remote {

@WebMethod(operationName="add", action="urn:addNumbers") @WebResult(name="return")

public int addNumbers(

@WebParam(name="num1")int number1,

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@WebMethod

@WebService(targetNamespace = "http://duke.org", name="AddNumbers") public interface AddNumbersIF extends Remote {

@WebMethod(operationName="add", action="urn:addNumbers")

@WebResult(name="return") public int addNumbers(

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@WebParam

@WebParam(name="num1") int number1,

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@WebResult

@WebMethod(operationName="add", action="urn:addNumbers") @WebResult(name="return")

@WebParam(name="num1") int number1,

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@SOAPBinding

@WebService(targetNamespace = "http://duke.org", name="AddNumbers")

@SOAPBinding(style=SOAPBinding.Style.RPC, use=SOAPBinding.Use.LITERAL)

public interface AddNumbersIF extends Remote {

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@RequestWrapper @ResponseWrapper

@WebMethod

@WebResult(targetNamespace = "")

@RequestWrapper(localName = "addNumbers", targetNamespace = "http:// server.fromjava/", className = "fromjava.client.AddNumbers")

@ResponseWrapper(localName = "addNumbersResponse", targetNamespace = "http:// server.fromjava/", className = "fromjava.client.AddNumbersResponse")

@WebParam(name = "arg0", targetNamespace = "”) int arg0, @WebParam(name = "arg1", targetNamespace = "”) int arg1) throws AddNumbersException_Exception;

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WS Programming

•  Defining the SEI (Service Endpoint Interface)

•  Marked with @WebService

•  Declaring the methods which are the web service operations.

•  Marked with @WebMethod

•  Implementing the SIB (Service Implementation Bean)

•  Defining the methods declared in the SEI.

•  Publishing the WS:

•  With core Java 6

•  With Application Server (Glassfish)

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Time Server

•  TimeServer is the SEI

•  TimeServerImpl is the SIB

•  A Java Application to publish the WS

(TimeServerPublisher)

•  Testing the WS:

•  With a Browser

•  With SOAPUI

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•  Publishing the service ( and the associated wsdl )

•  In the src directory:

wsimport -keep -p eser1.tsClient http://127.0.0.1:9877/ts?wsdl

•  Easily create the tsClientFromWSDL

Let’s see how…

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SERVICES IN

GLASSFISH

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GlassFish

•  An open source application server.

•  Provides a fully-featured implementation of Java EE 6:

•  JAX-WS

•  JAX-RS

•  JAXB

•  EJB

•  Web Container:

•  deploys servlets and web services.

•  Message-oriented middleware:

•  supporting JMS (Java Message Service).

•  RDBMS (Relational Database Management System)

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Apt (Annotation Processing Tool)

Usage: apt <apt and javac options> <source files>

-d <path>

where to place processor and javac generated class files -s <path>

where to place processor generated source files -nocompile

do not compile source files to class files -print

print out textual representation of specified types -factorypath <path>

where to find annotation processor factories -factory <class>

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Wsimport

wsimport [options] <WSDL_URI>

-b <path>

specify jaxws/jaxb binding files or additional schemas -d <directory>

specify where to place generated output files -keep

keep generated files -p <pkg>

specifies the target package -s <directory>

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.war files

•  Web Application archive file.

•  Standard structure to respect:

web deployment descriptor jax-ws deployment descriptor

AppName WEB-INF META-INF web.xml sun-jaxws.xml classes

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jax-ws.xml

•  Service Deployment descriptor:

•  specifies where to find the concrete service implementation when a

service is invoked.

•  name: name of the endpoint

•  implementation: where to find the SIB

•  url-pattern: must be equal to the one specified in web.xml

<?xml version="1.0" encoding="UTF-8"?> <endpoints xmlns="http://java.sun.com/xml/ns/jax-ws/ri/runtime" version="2.0"> <endpoint name="MyHello" implementation="hello.HelloImpl" url-pattern="/hello"/>! </endpoints>

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web.xml

•  Web Application deployment descriptor

?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http:// java.sun.com/j2ee/dtds/web-app_2_3.dtd"> <web-app> <listener> <listener-class>com.sun.xml.ws.transport.http.servlet.JAXRPCContextListener</listener-class> </listener> <servlet> <servlet-name>hello</servlet-name> <servlet-class>com.sun.xml.ws.transport.http.servlet.JAXRPCServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>hello</servlet-name> <url-pattern>/hello</url-pattern> </servlet-mapping> <session-config> <session-timeout>60</session-timeout> </session-config> </web-app>

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Exercise part 1

•  Implement a service for exposing soccer team details.

•  Use JAXWS annotations to generate and deploy the service

•  The service should offer the following two methods:

•  public Team getTeam(String name);

•  public List<String> getTeams();

•  Team should contain:

•  The name of the team

•  A list of players

•  Each player should contain:

•  The name of the player

•  The number on the player’s shirt.

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Exercise part 2

•  Use the WSDL exposed by the service to create a Java

client

•  Use WSImport

•  Use the Java client to print out to System.out

•  The list of all the teams

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MTOM

•  Message Transmission Optimization Mechanism (W3C)

•  Used with XML-binary Optimized Packaging (XOP)

•  Alternative to Soap with Attachments

•  Efficiency refers to size of the message

•  SwA: Base64 sends as text encoding leads to 33% increase in size

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ServerSide

Just a new Annotation… @MTOM

@WebService(endpointInterface = "server.ImageServer")

public class ImageServerImpl implements ImageServer {

…

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Client Side

•  Receiving doesn’t require anything since the WSDL

references an array of bytes…

•  Sending needs to be programmatically enabled…

BindingProvider bp = (BindingProvider) service;

SOAPBinding binding = (SOAPBinding) bp.getBinding(); binding.setMTOMEnabled(true);

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A Simple ImageServer

@WebService

@SOAPBinding(style = Style.RPC)

public interface ImageServer {

@WebMethod Image downloadImage(String name);

@WebMethod String uploadImage(Image data, String fileName); @WebMethod List<String> getImageNames();

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Handlers in JAX-WS

•  Message interceptors plugged into the JAX-WS runtime.

•  Both client-side and server-side.

•  Used to do additional processing of inbound/outbound

messages.

•  Client/Provider Authentication.

•  Client/Provider Performance Monitor.

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Protocol and Logical Handlers

•  Protocol Handlers:

•  may access or change the protocol specific aspects of the

message.

•  Only SOAPHandler actually available.

•  Logical Handlers:

•  protocol-agnostic.

•  act only on the payload of the message.

boolean handleMessage (C context) boolean handleFault (C context) void close (MessageContext context)

Handler<C extends MessageContext> LogicalHandler<C extends LogicalMessageContext> Set<QName> getHeaders() SOAPHandler<C extends SOAPMessageContext>

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Message Context

•  A bag of properties shared by:

•  client, client run-time, client-side

handlers.

•  provider, provider run-time,

provider-side handlers.

Map <String, Object>

Enum Scope MessageContext LogicalMessage getMessage() LogicalMessageContext Object[] getHeader(...) Set<String> getRoles() SOAPMessage getMessage() void setMessage(SOAPMessage) SOAPMessageContext •  Examples of properties:

•  MESSAGE_OUTBOUND_PROPERTY (Boolean): specifies message

direction.

•  INBOUND_MESSAGE_ATTACHMENTS (java.Util.Maps): access to the

inbound message attachments.

•  OUTBOUND_MESSAGE_ATTACHMENTS (java.Util.Maps): access to

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Handlers in practice

•  Handlers are programmer-written class that contains

callbacks.

•  Methods invoked by the JAX-WS runtime so that an application has

access to:

•  the underlying SOAP for SOAPHandlers

•  the payload for Logical Handlers.

•  A Handler can be injected into the handler framework in

two steps:

•  Create a Handler class (implemeting the *Handler interface) with

handleMessage() , handleFault() , close(). getHeaders() (only for SOAPHandler).

•  Place a handler within a handler chain.

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The RabbitCounter Example

•  The RabbitCounter service has one operation

(countRabbits) that computes the Fibonacci numbers.

•  a SOAP fault is thrown if the argument is a negative integer.

•  The service, its clients, and any intermediaries are

expected to process SOAP headers:

•  client injects a header block.

•  intermediaries and the service validate the information in the

header block.

•  generating a SOAP Fault if necessary.

•  Two ways to throw SOAP faults:

•  extend the Exception class and throw the exception

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The RabbitCounter Example

•  Injecting a Header Block into a SOAP Header.

•  FibClient generates a request against the RabbitCounter.

•  The client-side JWS libraries create a SOAP message that serves

as the request.

•  The UUIDHandler callbacks are invoked.

•  The handleMessage callback has access to the whole SOAP

message and injects a UUID (Universally Unique Identifier) value into the header.

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Order of execution in handler chain

•  Typically the top-to-bottom sequence of the handlers in

the configuration file determines the order of execution.

•  With some exeptions:

•  For outbound messages handleMessage and

handleFault in LogicalHandler execute before their

counterparts in SOAPHandler.

•  For inbound messages handleMessage and handleFault

in SOAPHandler execute before their counterparts in LogicalHandler.

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Example

Handler-chain: SH1 LH1 SH2 SH3 LH2 Inbound messages: SH1 SH2 SH3 LH1 LH2 Outbound messages: LH1 LH2 SH1 SH2 SH3

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Configuring the Client-Side Handler

•  With a configuration file:

In the ws-import generated class

FibC.RabbitCounterService simply add the annotation: @HandlerChain(file = "handler-chain.xml")

•  Or you can add the handler programmatically:

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SOAP Fault

•  In handler.fib.RabbitCounter a customized exception that

the @WebMethod countRabbits throws if it is invoked with a negative integer as argument.

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Adding a Logical Handler to the Client

•  To avoid the fault let’s add to the client the LogicalHandler

ArgHandler that:

•  intercepts the outgoing requests.

•  check the argument to countRabbits

•  change the argument if it is negative.

•  It uses a JAXBContext to extract the payload ( in this case

the body of the outgoing SOAP message).

•  Get – Check - Change - Set the arg0 (the argument of

CountRabbits).

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Adding a Service-Side SOAP Handler

•  To complete the example we need a service-side SOAP

handler to process the header block and throw a fault if needed.

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UEFA European League

•  Requirements:

•  Implement a Java Application which prints to the

console:

• All the city names where games are played

• All the players of all the qualified teams

• All the strikers of the Italian Team

•  The data source is provided as a web-service.

•  You can find the WSDL at:

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Exercise part 3

•  Change the teams service to use the data exposed by the

following UEFA European League web service

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Exercise part 4

•  Implement a SOAP handler that timestamps and logs all

the requests made to the service

•  Logging should occur on the client’s side and the log