Java Web Services [4/5]: Java API for XML Web Services

Topic 4

Java API for XML Web Services

Assoc.Prof. Dr. Thanachart Numnonda
www.imcinstitute.com
August 2010

Agenda
 Java APIs for Web Services
 JAX-RPC

 JAX-WS

2

Java APIs for Web Services

3

JWSDP
 Java Web Services Development Pack (JWSDP) is a free
software development kit (SDK) for developing Web
Services
 JWSDP has been replaced by GlassFish and WSIT and
several components are in Java SE 6.
 JWSDP APIs
 Java API for XML Processing (JAXP), v 1.3
 Java Architecture for XML Binding (JAXB), v 1.0 and 2.0
 JAX-RPC v 1.1
 JAX-WS v 2.0
 SAAJ (SOAP with Attachments API for Java)
 Java API for XML Registries (JAXR)
4

Java API for XML Processing (JAXP)
• JAXP enables applications to parse, validate and
transform XML documents.
• Java developers can invoke
• SAX parser
• DOM parser
• The main JAXP APIs are defined in the
javax.xml.parsers package
• SAXParserFactory
• DocumentBuilderFactory

5

Java API for XML Binding (JAXB)
• JAXB allows Java developers to access and process XML data
without having to know XML or XML processing.
• JAXB is a Java technology that enables you to generate Java
classes from XML schemas by means of a JAXB binding
compiler.
• unmarshalling
• XML instance documents into Java content trees
• marshalling
• Java content trees back into XML instance documents.

6

SAAJ (SOAP with Attachments
API for Java™)
• SAAJ provides a convenient API for constructing
and sending SOAP messages without having to
directly create the XML yourself.
• SAAJ was originally part of the Java API
for XML Messaging (JAXM) Separated out from
JAXM 1.0 into JAXM 1.1 and SAAJ 1.1
(SAAJ 1.3 (Java EE 5))
7

JAXR
• Standard Java API for performing registry operations
over diverse set of registries
Web service publication & discovery

• A unified information model for describing business
registry content
• Provides multi-layered API abstractions
Level 0: for UDDI
Level 1: for ebXML registry/repository
8

JAX-RPC

• XML data types to/from Java types mapping
• SOAP Message Handler framework
• WSDL to/from Java mapping
• Servlet-based Web service endpoint model
• JAX-RPC Client Programming Models
• Extensible type mapping

9

JAX-WS (JAX-RPC 2.0)
• New handler framework
• Metadata-based Web services
• Operational style improvement
• Asynchronous Web services
• Support for non-HTTP transport
• Interoperable attachments (as part of WS-I)
• Secure Web services (as part of Security)

10

JAXM

• JAXM is not part of Java EE 5
• JAXM-based asynchronous messaging on Java EE 5
is supported via
Message-driven Bean (MDB) in EJB 3 can receive
both JMS and JAXM message types
Connector 1.5 allows pluggability of various types
message providers (JAXM provider and JMS
provider)

11

Java APIs for Web Services Protocols
 SOAP
 JAXM 1.0 (JSR 67), SAAJ
 JAX-RPC => JAX-WS 2.0 (JSR 224)
 WSDL
 JAX-RPC => JAX-WS 2.0 (JSR 224)
 UDDI
 JAXR 1.0 (JSR 93)

12

Sun’s Web Services Stack

13

Remote Procedure Call (RPC)
Request

Response
Client System Server System

 RPC, COM, CORBA, RMI:

Synchronous communication: calling process blocks until
there is a response

More tightly coupled (than non-RPC model): client must
find recipients and know method and its arguments

Non persistent

Remote Procedure Calls

Client Interface Interface Servant

Stub Skeleton

Run Time Protocol Run Time


Common Interface between client and Server

Stub for client, Skeleton/Tie for server

On-the-wire protocol needs to be agreed upon

RPC Example – Java RMI
<<Interface>>
Java Remote
Interface

rmic compiler

Client Remote Object
Implementation

RMI Client RMI Server
Stub Skeleton

Java Remote Method Protocol (JRMP) is
On-the-wire protocol

Common Interface
 Service is described in IDL (Interface Description
Language)
 IDL ofCORBA service
 Java RMI interface in RMI (Language specific)
 WSDL for Web service

 Used by tools to statically or dynamically generate
and/or configure interfaces, proxies, and ties in a
network technology specific environment

What is JAX-RPC?
 Java™ API for XML-based RPC
 Web Services operations are performed by exchanging
SOAP 1.1 messages
 Services are described using WSDL
• WSDL is the contract between service provider and
client (only contract needed)
 Web service endpoints and clients use JAX-RPC
programming model
 Key technology for Web Services in the J2EE 1.4
platform

JAX-RPC Design Goals
 Easy to use programming model
• For both defining & using a service
 Hides all the plumbing
• You don't have to create SOAP messages yourself
 SOAP and WSDL-based interoperability
• Interoperate with any SOAP 1.1 compliant peers
 Extensibility and Modularity
• Support new versions of XML specification, i.e. SOAP 1.2
and beyond
• Message handler architecture

JAX-RPC Architecture
JAX-RPC JAX-RPC
Client WSDL Document Service Endpoint
Generated JavaWSDL WSDLJava
Code

Container Container

Client-side JAX-RPC Server-side JAX-RPC
Runtime System Runtime System

SOAP

HTTP

JAX-RPC Runtime System
 Core of a JAX-RPC implementation:
• Library that provides runtime services
for JAX-RPC mechanisms
• Implements some of the JAX-RPC APIs
 Client side:
• Can be implemented over J2SE™, J2EE™ or J2ME™
platforms
 Server-side:
• J2EE 1.3 or 1.4 Containers: EJB™ or Servlet

Developing a Web Service
Interfaces (java.rmi.Remote type)
Must follow JAX-RPC conventions

Implementation classes
Servlet-based endpoint model
Optional handler and serializer classes

tool
WSDL Service contract

Packaged application (war file)

JAX-RPC : Web Service Endpoint
JAX-RPC
Service Endpoint
WSDL<-->Java

WSDL Document Container

Server-Side
JAX-RPC
Runtime
System
SOAP

HTTP

Quick overview of JAX-WS
 Easy way to use Java API for XML Web Services
 Replace JAX-RPC
 Just add @annotation to POJO
 XML Descriptor free programming
 Layer architecture
 SOAP 1.2 (Document/Literal)
 Use JAXB for data binding
 Protocol and transport independence
 Part of Java SE6 and Java EE 5 Platform
27

JAX-WS Layered Architecture

28

What Does It Mean?
• Upper layer uses annotations extensively
• Easy to use
• Great toolability
• Fewer generated classes
• Lower layer is more traditional
• API-based
• For advanced scenarios
• Most application will use the upper layer only
• Either way, portability is guaranteed

29

Two ways to create a Web Service
• Starting from a WSDL file
> Generate classes using wsimport (=> xjc)
> WS interface
> WS implementation skeleton class
> Implement WS interface
> Build and deploy
• Starting from a Java class (POJO)
> Annotate POJO
> Build and deploy
> WSDL file generated automatically

30

Start with a Java Class

31

Server-Side Programming Model: POJO

1 Write a POJO implementing the service
2 Add @WebService annotation to it
3 Build and Deploy the application
WSDL is automatically generated at runtime
1 Point your clients at the WSDL
e.g. http://myserver/myapp/MyService?WSDL

32

Example 1: Servlet-Based Endpoint
@WebService
public class Calculator {
public int add( int a, int b) {
return a + b;
}
}

• @WebService annotation
• All public methods become web service operations
• WSDL/Schema generated automatically
• Default values are used
33

Service Description Default Mapping
• Java mapping => WSDL

34

Example 2: EJB-Based Endpoint
@WebService
@Stateless
public class Calculator {
public int add( int a, int b) {
return a + b;
}
}

• It’s a regular EJB 3.0 component, so it can use any
EJB features
> Transactions, security, interceptors...

35

Customizing through Annotations
@WebService(name=”CreditRatingService”,
targetNamespace=”http://example.org”)
public class CreditRating {

@WebMethod(operationName=”getCreditScore”)
public Score getCredit(
@WebParam(name=”customer”)
Customer c) {
// ... implementation code ...
}
}

36

Start with a WSDL file

37

Generating an interface from WSDL
• WSDL => Java generation

38

Implementing a Web Service from
a Generated Interface

39

Server Side Web Service

40

JAX-WS uses JAXB for Data Binding

41

add() Parameter : Example

42

JAXB XML Schema to Java Mapping

43

Client Side Programming

44

Java SE Client Side Programming

• Point a tool (NetBeans or wsimport) at the WSDL
for the service
wsimport http://example.org/Calculator.wsdl
• Generate annotated classes and interfaces
• Call new on the service class
• Get a proxy using a get<ServiceName>Port method
• Invoke any remote operations

45

Example : Java SE-Based Client

CalculatorService svc = new CalculatorService();
Calculator proxy = svc.getCalculatorPort();
int answer = proxy.add(35, 7);

• No need to use factories
• The code is fully portable
• XML is completely hidden from programmer

46

Java EE Client Side Programming

• Point a tool (NetBeans or wsimport) at the WSDL
for the service
wsimport http://example.org/calculator.wsdl
• Generate annotated classes and interfaces
• Inject a @WebServiceReference of the
appropriate type
• No JNDI needed
• Invoke any remote operations
47

Example : Java EE-Based Client

@Stateless
public class MyBean {
// Resource injection
@WebServiceRef(CalculatorService.class)
Calculator proxy;

public int mymethod() {
return proxy.add(35, 7);
}

48

Annotations Used in JAX-WS
• JSR 181: Web Services Metadata for the
Java Platform
• JSR 222: Java Architecture for XML
Binding (JAXB)
• JSR 224: Java API for XML Web Services
(JAX-WS)
• JSR 250: Common Annotations for the
Java Platform

@WebService
• Marks a Java class as implementing a
Web Service, or a Java interface as
defining a Web Service interface.
• Attributes
> endpointInterface
> name
> portName
> serviceName
> targetNamespace
> wsdlLocation

@WebMethod
• Customizes a method that is exposed as
a Web Service operation
• The method is not required to throw
java.rmi.RemoteException.
• Attributes
> action
> exclude
> operationName

@WebParam
• Customizes the mapping of an individual
parameter to a Web Service message
part and XML element.
• Attributes
> header
> mode
> name
> partName
> targetNamespace

@WebResult
• Customizes the mapping of the return
value to a WSDL part and XML element.
• Attributes
> header
> name
> partName
> targetNamespace

JAX-WS - Provider
• Web Service endpoints may choose to work at
the XML message level by implementing the
Provider interface.
• The endpoint accesses the message or
message payload using this low-level, generic
API
• Implement one of the following
> Provider<Source>
> Provider<SOAPMessage>
> Provider<DataSource>

JAX-WS - Dispatch
• Web service client applications may choose to
work at the XML message level by using the
Dispatch<T> APIs.
• The javax.xml.ws.Dispatch<T> interface
provides support for the dynamic invocation of
service endpoint operations.
• Similar to Provider on server side

Resources
 Some contents are borrowed from the presentation
slides of Sang Shin, Java™ Technology Evangelist,
Sun Microsystems, Inc.
 Web Services and Java, Elsa Estevez, Tomasz
Janowski and Gabriel Oteniya, UNU-IIST, Macau

59

Thank you

thananum@gmail.com
www.facebook.com/imcinstitute
www.imcinstitute.com

60

Java Web Services [4/5]: Java API for XML Web Services

In this document

More Related Content

What's hot

Viewers also liked

Similar to Java Web Services [4/5]: Java API for XML Web Services

More from IMC Institute

Recently uploaded

Java Web Services [4/5]: Java API for XML Web Services