Java web services using JAX-WS

Java web services using JAX-
WS

Speaker Name Lalit Mohan Chandra Bhatt
Company Name Crayom Engineering Services

Scope
• Understanding how JAX-WS can be used
to implement SOAP based web services
both at server and client side.

Are webservices hard !
Dave Podnar's Five Stages of Dealing with Web Services

●
Denial - It's Simple Object Access Protocol, right?
●
Over Involvement - OK, I'll read the SOAP, WSDL, WS-I BP, JAX-RPC,
SAAJ, JAX-P... specs. next, I'll check the Wiki and finally follow an example
showing service and client sides.
●
Anger - I can't believe those #$%&*@s made it so difficult!
●
Guilt - Everyone is using Web Services, it must be me, I must be missing
something.
●
Acceptance - It is what it is, Web Services aren't simple or easy

Jargons Jargons
XML XSD
XSLT Xpath JAXP
SAX DOM JAXB StaX
SOAP WSDL UDDI
JAX-RPC JAX-WS JAX-RS
SAAJ WS* BP
Axis Metro
ESB
SOA

Webservice
Invoked initially

Web service details – WSDL on XML

Request - SOAP on XML Server
Client
Reposnse – SOAP on XML

Invoked whenever message
exchange happens

Webservice – JAX-WS way
Plain old Java Object (POJO) can be easily exposed as
●

web service.
●
Annotation driven
●
Data binding through JAXB
●
Server Independent

JAX-WS – Servlet Way
●
Write the class
●
Annotate
●
Register in web.xml
●
Deploy – The server runtime will
➢
Generate and publish WSDL.
➢
Map SOAP request to a Java method invocation.
➢
Translate method return into a SOAP response.

@WebService
public class TemperatureConverter {

@WebMethod
public double celsiusToFarenheit(double temp){
...
}

@WebMethod
public double farenheitToCelsius(double temp){
...
}

}

<servlet>
<servlet-name>tempConv</servlet-name>
<servlet-class>
com.lalit.TemperatureConverter
</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>tempConv</servlet-name>
<url-pattern>/tempConv</url-pattern>
</servlet-mapping>

JAX-WS Servlet Way
1. Get WSDL
WSDL Published
On Server

2. SOAP request 3 4 5 6
Handler

JAXB Mapping
Chain

Java endpoint
Web Service
Dispatcher
Clientt

Endpoint
Listener
SOAP
11. SOAP resp 10 9 Fault 8 7
Processing

JAX-WS EJB 3.0 way
Annotate
●

Deploy ejb jar
●

JAX-WS – EJB 3.0 way
@Stateless
@WebService
public class TemperatureConverter {

//Rest code remains same.

JAX-WS – JavaSE Endpoint
●
Starting Java 6
●
Generate the artifact using wsgen tool.
●
wsgen tool generates JAXB mapped classes
●
Use embedded HttpServer to deploy the webservice

JAX-WS – JavaSE Endpoint
public static void main(String[] args) {
TemperatureConverter tc= new
TemperatureConverter();

//Java comes with an embedded Http server
//which is used to host the service
Endpoint endpoint = Endpoint.publish
("http://localhost:8080/tempConv", tc);

//Keeping commented, keeps the server running
/*endpoint.stop();*/
}
}

JAX-WS – Client side
●
Generate artifact using wsimport pointing to WSDL
●
wsimport generates JAXB binding classes and service
endpoint
●
Call the web service using service end point

JAX-WS – Client side
//Make the instance of service class
TemperatureConverterService service =
new TemperatureConverterService();

//Get port to invoke webservice
TemperatureConverter port =
service.getPort
(TemperatureConverter.class);

//Call the web service.
double fahr = port.celsiusToFarenheit(100);

JAX-WS - start from WSDL
●
JAX-WS supports start from WSDL approach

@WebService(name = "TemperatureConvertor",
endpointInterface="com.crayom.ws.TemperatureConvertor",
targetNamespace = "http://ws.crayom.com/",
wsdlLocation = "WEB-INF/TemperatureConvertorDocStyle.wsdl")
public class TemperatureConvertorService implements
TemperatureConvertor {

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 - Provider
@WebServiceProvider(serviceName = "TempConvProvider",
portName="TempConvPort",
targetNamespace = "http://www.crayom.com/om",
wsdlLocation="WEB-INF/wsdl/TempConvProvider.wsdl")
@ServiceMode(value=Service.Mode.PAYLOAD)
public class TempConvProvider implements Provider<Source>{

public Source invoke(Source request) {
…
return resp; Provide WSDL
} yourself

}
PAYLOAD gives the body of message.
MESSAGE will give whole SOAP Message

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
●

JAX-WS - Dispatch
Service service = Service.create(url, serviceName);

Dispatch<Source> sourceDispatch =
service.createDispatch(portQName,
Source.class,
Service.Mode.PAYLOAD);
//request is a XML which is put into SOAP payload
StreamSource streamSource = new StreamSource
(new StringReader(request));

Source result = sourceDispatch.invoke(streamSource);

JAX-WS - Apart from this
●
JAX-WS provides support for SOAP fault handling in terms of
exceptions.
●
JAX-WS supports handlers both on client and server side ,
which can process SOAP headers. SOAP headers are used to
build Quality of services (QOS).
●
JAX-WS supports asynchronous communication

Java web services using JAX-WS

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