Web-Service Example
Fundamentals
•
Roles
– Service provider
– Service Consumer
– Registry
•
Operations
– Publish (by provider)
– Find (by requester)
– Bind (by requester or invoker)
•
Web Service = Description + Service
– Service Description
• Details of interfaces (data types, operations, bindings, location, …) • Details of implementation
• Published to registry
– Service
• Software module deployed for invocation
UDDI
WSDL
Service
Search for
Service
Description
Sea c
o
services
Retrieve service
description
Client
Invoke service
Service
SOAP Messages
Life Cycle of Web Services
• Build
– creation & publication of a service interface
• Deploy
– proceed to the creation and deployment of service
– deployment of the executables for the Web service into an
execution environment
• Run
i
i
f h W b
i
b
h
i
– invocation of the Web service by the service requestor
• Manage
– administration of the Web service application
– Security, availability, performance, OoS
Step 1: Provide Interface of Service
/** * Exchange rate service from country1 to country2 */
public interface IExchange
{
float getRate( String country1, String country2 );
void setValue( String country double value );
void setValue( String country, double value );
double getValue( String country );
Step 2: Provide Implementation of Service
public class Exchange implements IExchange
{
{
float getRate( String country1, String country2){
return getValue(country1)/ getValue(country2);
}
void setValue( String country, double value ){
}
….. }
double getValue( String country ){
…. }
}
Step 3: Publish the Service
• Step 3 1 : generate standard web service
• Step 3.1 : generate standard web service
description using standard tool (java2wsdl)
• Step 3.2 : start web server on specified url
• Step 3.3 : publish service for SOAP client
Step 3.1: Create WSDL from interface file
java2wsdl examples.publish.Exchange -e
http://localhost:8004/glue/urn:exchange
Result : - create and write to file “Exchange.wsdl”
value (
blue
= mandatory)
meaning
classname
name of java class to process
-d directory
directory to write files, "." by default
-e endpoint
endpoint of service
-g
include GET/POST binding
-m map-file
read mapping instructions
-n namespace
override default namespace of service
-r description
description of web service
-s
include SOAP binding
-x command-file
command file to execute
Service
WSDL Template
Port
(e.g. http://host/svc) Binding (e.g. SOAP)portType
Port
Binding
Abstract interface
p
yp
operation(s) inMesage outMessage- <definitions name="Exchange" targetNamespace="http://www.themindelectric.com/wsdl/Exchange/" xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" - xmlns=http://schemas.xmlsoap.org/wsdl/ - --- > - <message name="getValue0SoapIn">
- <part name="country" type="xsd:string"> </part> </message>
- <message name="getValue0SoapOut">
- <part name="Result" type="xsd:double"> </part> </message>
- <message name="setValue1SoapIn">
- <part name="country" type="xsd:string"></part> - <part name="value" type="xsd:double"> </part> </message>
<message name="setValue1SoapOut" /> - <message name="getRate2SoapIn">
- <part name="country1" type="xsd:string"> </part> - <part name="country2" type="xsd:string"></part> </message>
- <message name="getRate2SoapOut">
- <part name="Result" type="xsd:double"> </part> </message>
-<portType name="ExchangeSoap">
i " V l " O d " " - <operation name="getValue" parameterOrder="country">
<input name="getValue0SoapIn" message="tns:getValue0SoapIn" /> <output name="getValue0SoapOut" message="tns:getValue0SoapOut" /> </operation>
- <operation name="setValue" parameterOrder="country value"> <input name="setValue1SoapIn" message="tns:setValue1SoapIn" /> <output name="setValue1SoapOut" message="tns:setValue1SoapOut" /> </operation>
- <operation name="getRate" parameterOrder="country1 country2"> <input name="getRate2SoapIn" message="tns:getRate2SoapIn" /> <output name="getRate2SoapOut" message="tns:getRate2SoapOut" /> </operation>
<binding name="ExchangeSoap" type="tns:ExchangeSoap">
<soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http" /> - <operation name="getValue">
<soap:operation soapAction="getValue" style="rpc" /> - <input name="getValue0SoapIn">
<soap:body use="encoded" namespace="http://tempuri.org/book.soap.Exchange" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" />
/i </input>
- <output name="getValue0SoapOut">
<soap:body use="encoded" namespace="http://tempuri.org/book.soap.Exchange" encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" /> </output> </operation> </binding> i "E h " <service name="Exchange">
<documentation>An interface for getting exchange rates.</documentation> <port name="ExchangeSoap" binding="tns:ExchangeSoap">
<soap:address location="http://199.174.21.187:8004/soap/exchange" /> </port>
</service>
</definitions>
public class ExchangeServer
{
public static void main( String[] args ) throws Exception {
//
step 3.2 start server
HTTP.startup(
http://localhost:8004/soap
);
// initialize instance of Exchange
Exchange exchange = new Exchange();
exchange.setValue(“usa”, 1);
exchange.setValue(“japan”, 0.4);
// step 3.3 publish
Registry.publish( “urn:exchange”, new exchange());
}
}
Step 4: Client Invocation of Service
• Step 4 1 : proxy client stub is generated
• Step 4.1 : proxy client stub is generated
dynamically using standard tool (wsdl2java)
• Step 4.2 : client implementation uses the
service by binding and utilizing web service
y
g
g
on specified url
Step 4: Client Interface of Service
package book.soap;
…. import packages …
public class ExchangeClient
{
{
public static void main( String[] args ) throws Exception {
String url = "http://localhost:8004/glue/urn:exchange.wsdl";
// Step 4.1 and 4.2
IExchange exchange = (IExchange)Registry.bind( url, IExchange.class );
// invoke the web service as if it was a local java object
exchange.getRate( "usa", "japan" );
System.out.println( "usa/japan exchange rate = " + rate );
}
SOAP
• Service oriented
• Service oriented
architecture
SOAP Request Message
SOAP Request
<?xml version='1.0' encoding='UTF-8'?> <soap:Envelope xmlns:soap='http://schemas.xmlsoap.org/soap/envelope/' p p p p p g p p xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xmlns:xsd='http://www.w3.org/2001/XMLSchema' xmlns:soapenc='http://schemas.xmlsoap.org/soap/encoding/' soap:encodingStyle='http://schemas.xmlsoap.org/soap/encoding/'> <soap:Body> <n:getRate xmlns:n='http://tempuri.org/examples.service.Exchange'> <country1 xsi:type='xsd:string'>usa</country1> 2 i ' d i ' j / 2 <country2 xsi:type='xsd:string'>japan</country2> </n:getRate> </soap:Body> </soap:Envelope>SOAP Response Message
SOAP Response
<?xml version='1.0' encoding='UTF-8'?>?xml version 1.0 encoding UTF 8 ?
<soap:Envelope xmlns:soap='http://schemas.xmlsoap.org/soap/envelope/' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xmlns:xsd='http://www.w3.org/2001/XMLSchema' xmlns:soapenc='http://schemas.xmlsoap.org/soap/encoding/' soap:encodingStyle='http://schemas.xmlsoap.org/soap/encoding/'> <soap:Body> <n:getRateResponse xmlns:n='http://tempuri.org/examples.service.Exchange'> <Result xsi:type='xsd:double'>2.5</Result> </n:getRateResponse> </soap:Body> </soap:Envelope>
