1. Java EE 6 – Web Service
Vladan Pulec

2. Objectives
 Overview
 Distinguish between the two types of web
services
 RESTful Service & Demo
 Web Service & Demo

3. Key Features
• Platform independent
• Language independent
• Interoperable across disparate programming
languages
• Leveraging existing technologies (HTTP, XML)
• Supported in SE and EE version of Java

4. Benefits
• Flexibility of supporting unknown future client
platforms
• Use of HTTP
• Easier communication via firewalls and proxies
• Flexible to use a variety of transmission
protocols (ie. SMTP)

5. Disadvantages
• Verbose (can be slower than other
middleware technologies)
• Relying on HTTP, the roles are fixed (only one
party can use the service of the other).
– Service cannot push, client must pull

6. Web Service Standards
• There are two prevailing types:
• Representational State Transfer (REST) – JSR 311
• Simple Object Access Protocol (SOAP) – JSR 224

7. RESTful Web Services
• Representation State Transfer (REST) revolve
around resources (candidate, client, etc)
• The state of the resource is captured and
transferred using the service

8. JAX-RS API
• Does not require any specific data format
• Often CSV, JSON (JavaScript Object Notation), or
XML
• Provides only server-side API
• Can be combined with JAXB or any other Java
XML API

9. Web Service Endpoints
• Remotely executable components that exist
on the server and are executed as a result of
receiving a web service request.
• Both JAX-RS and JAX-WS can use the
following:
• Annotated POJOs
• Session bean components (Stateless or Singleton
beans only)

10. JAVA-RS Endpoints
• The end point is:
• Annotated class created to provide web service
functionality
• Is instantiated per request
• Does not require an EJB container
• JAVA-RS will provide a servlet implementation
to handle the requests

11. JAVA-RS Web Endpoints
• Must have the following:
– @javax.ws.rs.Path class annotation
– Public methods that are annotated with method
designator (ie. @GET)
– Uses @Produces and/or @Consumers annotations
– Cannot be abstract
• Web.xml must have a web a JAVA-RS servlet
configured
– Classes with @Path annotation will be handled by
it.

12. REST Example
1. A resource is given a specific URL (such as
http://localhost/clients/adobe)
2. HTTP methods are used to perform operations
– HTTP GET – retrieves the resource representation
– HTTP POST – adds new element to the resource
– HTTP PUT – creates or updates resource
– HTTP DELETE – deletes the resource
• Content can be of any MIME Type (text, XML, etc.)

13. SOAP Web Services
• Simple Object Access Protocol (SOAP)
• More complex than REST but provides more
benefits
• To implement SOAP client, developer only
needs to know the Web Services Description
Language (WSDL) file, which exposes all API
information
• Utilizes HTTP request/response and XML

14. JAX-WS
• Replaces JAX-RPC
• Required minimal knowledge of XML or WSDL
to use basic services
• Provides both server and client APIssd SOAP
Client Service
JAX-WS runtime JAX-WS runtimeSOAP Message

15. Sample SOAP Request
• <SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/“
xmlns:xsd="http://www.w3.org/2001/XMLSchema“ xmlns:xsi="http://www.w3.org/2001/XMLSchema-
instance">
• <SOAP-ENV:Header>
• <wsse:Security xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-
1.0.xsd">
• <wsse:UsernameToken>
• <wsse:Username>123456</wsse:Username>
• <wsse:Password>mypassword</wsse:Password>
• </wsse:UsernameToken>
• <service_attributes ignore_warnings="false" />
• </wsse:Security>
• </SOAP-ENV:Header>
• <SOAP-ENV:Body>
• <ser:findByTestCenterID xmlns:ser="http://services.capacity.vue/">
• <testCenterID>4</testCenterID>
• </ser:findByTestCenterID>
• </SOAP-ENV:Body>
• </SOAP-ENV:Envelope>
sd SOAP
Envelope
Header
Body

16. Sample SOAP Response
• <soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
• <soap:Body>
• <ns2:findByTestCenterIDResponse xmlns:ns2="http://services.capacity.vue/">
• <workstationSearchResponse>
• <testCenter id="4" name="Electronic Systems" tws="-1" />
• <workstationRules>
• <workstationRule activeRuleCount="1">
• <asset assetCategoryCode="Workstation" assetID="53412"
• assetName="Test 7" siteID="4" isEnabled="true" />
• </workstationRule>
• </workstationRules>
• </workstationSearchResponse>
• </ns2:findByTestCenterIDResponse>
• </soap:Body>
• </soap:Envelope>

17. JAVA-WS Endpoints
• Must have the following:
– @javax.jws.WebService annotation
– Public methods (cannot be final or static) with
@javax.jws.WebMethod annotation
– Class cannot be abstract or final
– Must have no args constructor

18. Data Types
• JAX-WS does not contain JAVA to XML binding
• Java Architecture for XML Binding (JAXB) is
designed to handle the binding
• Basic Java types are supported, complex ones
require JAXB programming

19. Java APIs for Web Services
JDOM – provides OO Java model of an XML document
JAXP – abstraction of an XML processing
JAXB – converts objects to XML schemas
JAX-RPC – remote access API (replaced by JAX-WS)
JAXR – standard for using UDDI registries
SAAJ – standard for transmitting and parsing SOAP messages
JAX-RS – RESTful API
JAX-WS – high-level web service API

20. Additional Resources
JSR 224 – Java API for Web Services (JAX-WS)
JSR 331 – Java API for Restful Services (JAX-RS)