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Web ServicesFarag Zakaria
ITI-JAVA 30
Agenda
•Web services concept.•Why web services?•When to use web services•Web services architecture•SOAP •WSDL• JAX-WS• JAX-WS vs. JAX-RPC•RESTful web services
Web services concept
•Web service is a software system identified by a URI whose public interfaces and bindings are defined ,described and discovered by XML artifacts.(W3C)
•Client server application•Application to application communication•Interoperability (standard
communication) •Neutral (platform & language
independent).
Agenda
•Web services concept.•Why web services?•When to use web services•Web services architecture•SOAP •WSDL• JAX-WS• JAX-WS vs. JAX-RPC•RESTful web services
Why web services
•Interoperability (SOAP messaging).•Economical (recycled components, no
installation and tight integration of software).
•Accessible (applications are exposed and accessed on the web.)
•Available (services are on any device, any where, anytime.)
•Scalable (no limit on scope of application and their number.)
Example
Agenda
•Web services concept.•Why web services?•When to use web services?•Web services architecture•SOAP •WSDL• JAX-WS• JAX-WS vs. JAX-RPC•RESTful web services
When to use web services? •Applications do not have severe
restrictions on reliability and speed.•Cooperation among different application.•Upgrading services independently from
clients without changing the WSDL.•Services can be easily expressed with
simple request/response semantics and simple state
•
Agenda
•Web services concept.•Why web services?•When to use web services?•Web services architecture•SOAP •WSDL• JAX-WS• JAX-WS vs. JAX-RPC•RESTful web services
Web services architecture
Agenda
•Web services concept.•Why web services?•When to use web services?•Web services architecture•SOAP •WSDL• JAX-WS• JAX-WS vs. JAX-RPC•RESTful web services
SOAP messaging
SOAP(Simple Object Access Protocol)
•Define communication format between client and web service(XML message format).
•Wire protocol extension for conveying RPC calls.
•SOAP is not a transport protocol. You must attach your message to a transport mechanism like HTTP.
SOAP structure• A SOAP message is contained in an envelop.• The envelop element in turn contain (in order)
1. An optional header with one or more child entries. (security , transaction) 2. A body element that can contain one or more child entries. These child entries may contain arbitrary XML data.(application data)
• Header entries may optionally have a “mustUnderstand” attribute. mustUnderstand=1 recipient must process header mustUnderstand=0 optional header
SOAP structure(cont.)
•The body contains the XML message that you are transmitting.
• The message format is not specified by SOAP.The <Body></Body> tag pairs are just a way to notify the recipient that the actual XML message is contained therein.The recipient decides what to do with the message.
Agenda
•Web services concept.•Why web services?•When to use web services?•Web services architecture•SOAP •WSDL• JAX-WS• JAX-WS vs. JAX-RPC•RESTful web services
WSDL(Web Service Description Language)•Defines what your service does and how it
is invoked.•Guideline for constructing SOAP message.•XML language for writing
APIs(generating client code to use the web service).
•Verbose
WSDL documents parts
•Data definition (in XML) for custom types.•Abstract message definitions (request,
response)•Organization of messages into “ports” and
“operations” (classes and methods).•Protocol bindings (to SOAP, for example)•Service point locations (URLs)
WSDL document parts(cont.)
WSDL document parts(cont.)
WSDL document parts(Data Definition)
Agenda
•Web services concept.•Why web services?•When to use web services?•Web services architecture•SOAP •WSDL•JAX-WS• JAX-WS vs. JAX-RPC•RESTful web services
JAX-WS
•Simpler way to develop/deploy web services- POJO + Annotation.- No deployment descriptor is needed.- Layered programming model
•Layered programming model- Server side- Client side- Business layer
Programming model(server side)•Write a POJO implementing the service•Add @WebService annotation to it•Deploy the application•Point your clients at the WSDL
http://mysite/myapp/service.wsdl
Example(Server side)
@WebService(name="AddNumbers", portName="CalculatorPort", serviceName="CalculatorService")public class NumbersWebService{ @WebMethod(operationName="add") @WebResult(name="result") public int add(@WebParam(name="first") int first,
@WebParam(name="second") int second) { return first + second; }}
Programming model(client side)•You need to know the url of WSDL•Generate service classes and interfaces.•Create object from service class•Get a proxy using a
get<ServiceName>Port method.•Invoke any remote operations.
Example(Client side)
•CalculatorService service = new CalculatorServiceLocator();
AddNumbers calc = service.getCalculatorPort();
System.out.println(calc.add(3, 4));
Agenda
•Web services concept.•Why web services?•When to use web services?•Web services architecture•SOAP •WSDL• JAX-WS•JAX-WS vs. JAX-RPC•RESTful web services
JAX-WS vs. JAX-RPCJAX-RPC JAX-WS
Map to JAVA 1.4 Map to JAVA 1.5 and higher
Support SOAP 1.1 Support SOAP 1.1 and SOAP 1.2
Has its own data mapping model Data mapping model (JAXB)
Support MTOM through (JAXB)
Asynchronous communication
JAX-WS Demo
RESTful web services
Agenda
•REST Architecture principales •RESTful web services & WADL.•REST vs. Traditional web services•RESTful advantages
REST Architecture principales
•Representational State Transfer.•Every thing is a resource.•Resources are addressable.•Resources have an interface(operations
and data types).•Protocol is client-server, stateless,
cacheable, layered.
Agenda
•REST Architecture principales •RESTful web services & WADL.•REST vs. Traditional web services•RESTful advantages
RESTful web services & WADL.
•REST applied to web services.- web service accessible through URI.- operations are HTTP primitives(PUT,GET,..).- Web services returns a MIME type(XML, JSON, …).
•More resource efficient than SOAP•RESTful web services
- java class + annotations (for URI, operations, Data types).
RESTful web services & WADL.(cont.)
•Annotations- @Path(“”) for URI of service.- @GET,@POST,.. for Http methods.- @Produces(“…”) to define format of returned data- @Consumes (“…”) to define format of accepted input data
RESTful web services & WADL.(cont.)
<servlet> <servlet-name>ServletAdaptor</servlet-name> <servlet-class>
com.sun.jersey.spi.container.servlet.ServletContainer
</servlet-class> <load-on-startup>1</load-on-startup></servlet><servlet-mapping> <servlet-name>ServletAdaptor</servlet-name> <url-pattern>/resources/*</url-pattern></servlet-mapping>
RESTful web services & WADL.(cont.)
@Path("/hello")
@Consumes("text/html")
public class RESTWSTest{ @GET @Produces("text/html") public String sayHello(@QueryParam("name") String name) { return "<html><body><h1>Hello " + name +
"</h1></body></html>"; }
}
RESTful web services & WADL.(cont.)
• WADL web application description language.- easy to understand.- HTTP assumed.
• XML-based language.• Development language + platform neutral.• Aligned with REST terminology.• WADL elements
- resources- methods- representations
WADL<application><doc jersey:generatedBy="Jersey: 1.1.4 11/10/2009 05:36
PM"/><resources
base="http://localhost:8080/WebServicesREST/resources/"><resource path="/hello"> <method id="sayHello" name="GET"> <request> <param name="name" style="query" type="xs:string"/> </request> <response> <representation mediaType="text/html"/> </response> </method></resource></resources></application>
Agenda
•REST Architecture principales.•RESTful web services & WADL.•REST vs. Traditional web services•RESTful advantages
REST vs. Traditional web services
•Traditional web services- a lot of custom methods(ports according to business).- use http to transport soap
•RESTful- fixed methods(Http methods).- Http is the protocol.
Agenda
•REST Architecture principales •RESTful web services & WADL.•REST vs. Traditional web services•RESTful advantages
RESTful advantages
•More secure over http (use web port 80)•Ease of testing (only browser needed).•Thin client.•Save memory.(no need to build xml tree in memory).
RESTful Demo
Any Questions!??
If time allowed
•SOAP Handler Demo
References •JavaPassion web site•Sun Java JEE6 tutorial•Sun Java Web Services tutorial
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