WEB SERVICES
Topics
Understand Web Services and its
types
Implement WSDL File
Create a SOAP based web service
Create a RESTful web service
Web Services-Introduction
Why Web Services
Examples of Using Web Services
Web Services
Web Services - SOAP
Web Services - SOAP
Web Services Interaction - SOAP
Relationship between first-generation
specification
UDDI is accessed using SOAP
enables discovery of binds to
WSDL
enables communication between
describes
Web Service
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Relationship between first-generation
specification
XML defines types and
Schema payload structure for
SOAP
defines types for binds to
WSDL
is accessed using
Enables discovery of
UDDI
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Web Services - SOAP
SOAP
SOAP Format
Example of SOAP Request
Example of SOAP Response
WSDL
WSDL
Example of WSDL File
Structure of a WSDL
WSDL definition
<types>
….
</types>
abstract
definition
<message>
…
</message>
<portType> or <interface>
….
</portType> or </interface>
concrete
definition
<binding>
….
</binding>
<service>
…
</service>
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Structure of a WSDL
Definition documents acts as building blocks for a service description:
Abstract + Concrete = Service Definition
Service Definition + Supplementary Definitions = Service Description
Abstract: The description of a Web service interface, independent of implementation
details, is referred to as the abstract. Within a WSDL document, this abstract interface
definition is primarily made up of the interface/porttype and message constructs. It is
further supported by the types construct, which is often classified separately.
Eg: In a component-based architecture, the service interface is often compared to the
Interface Definition. Language (IDL) file used to describe a component interface.
Concrete: Specific location and implementation information about a Web service are the
concrete parts of a WSDL document, as represented by the binding, service, and
endpoint (or port) elements.
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Service definition to WSDL document
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WSDL
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WSDL-Abstract interface/portType definition
Individual Web service interfaces are represented by WSDL interface/portType elements.
These constructs contain a group of logically related operations. In a component-based
architecture, a WSDL interface/portType is comparable to a component interface. An
operation is therefore the equivalent of a component method, as it represents a single
action or function.
Eg:
<definitions>
<interface or portType name="Catalog">
<operation name="GetBook">
…
</operation>
</interface or portType >
</definitions>
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WSDL-Abstract interface/portType definition
A typical operation element consists of a group of related input and output messages.
The execution of an operation requires the transmission or exchange of these messages
between the service requestor and the service provider.
Operation messages are represented by message constructs that are declared separately
under the definitions element. The message names then are referenced in the operation’s
input or output child elements.
Eg:
<definitions>
….
<message name="BookInfo">
…
</message>
<interface or portType name="Catalog">
<operation name="GetBook">
<input name="Msg1" message="BookInfo" />
</operation>
..
</definitions>
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WSDL- message
A message element can contain one or more input or output parameters that belong to
an operation.
Each part element defines one such parameter. It provides a name/ value set, along with
an associated data type.
In a component-based architecture, a WSDL part is the equivalent of an input or output
parameter (or a return value) of a component method.
Eg:
<definitions>
<message name="BookInfo">
<part name="title* type>
Field Guide
</part>
<part name="author* type="xs:string">
Mr. Teshale
</part>
</message>
</definition
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WSDL-Abstract
Here’s a brief summary of the fundamental constructs that can be assembled to establish
abstract interface definition:
* interfaces represent service interfaces, and can contain multiple operations
* operations represent a Web service function, and can reference multiple messages
* messages represent collections of input or output parameters, and can contain multiple parts
* parts represent either incoming or outgoing operation parameter data
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Web Services - SOAP
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SOAP
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Web Services - SOAP
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SOAP Format
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Envelope construct
<env:Envelope xmlns:env="http: //www.w3.org/2003/05/soap-envelope">
<env:Header>
…
</env:Header>
<env: Body>
…
</env: Body>
</env:Envelope>
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Header construct
<env:Envelope xmlns;env="http://www.w3.org/2003/05/soap-envelope">
<env:Header>
<n:shipping >
UPS
</n:shipping>
</env:Header>
<env:Body>
…
</env:Body>
</env:Envelope>
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Body construct
<env:Envelope xmina:enva"http; //www.w3 .org/2003/05/soap-envelope”>
<env:Header>
…
</env:Header>
<env: Body>
<x:Book xmlns:x="http://www. examples.ws/">
<x:Title>
Service-Oriented Architecture
A Field Guide to Integrating XML
and Web services
</x:Title>
</x:Book>
</env:Body>
</env:Envelope>
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fault construct
<env:Envelope xmlns:env="http: //www.w3 .org/2003/05/soap-envelope">
<env:Body>
<env: Fault>
<env:Code>
<env:Value>
env:VersionMismatch
</env:Value>
</env:Code>
<env: Reason>
<env:Text xml:lang="en">
versions do not match
</env:Text>
</env:Reason>
</env:Fault>
</env:Body>
</env:Envelope>
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Example of SOAP Request
<?xml version="1.0"?>
<soap: Envelope
xmlns:soap="http://mm.w3.org/20@1/12/soap-envelope”
soap:encodingStyle="http://www.w3. org/2001/12/soap-encoding">
<soap:Body xmlns:s="http://ww. stock_brokerage.org/stock">
<s:GetStockPrice>
<s:StockName>Oracle</s:StockName>
</s:GetStockPrice>
</soap:Body>
</soap:Envelope>
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Example of SOAP Response
<?xml _version="1.0”?>
<soap:Envelope
xmlns : soap="http://www.w3.0rg/2001/12/soap-envelope”
soap:encodingStyle="http: //m.w3.org/2001/12/soap-encoding”>
<soap:Body xmlns:s="http://www.Stock_brokerage.org/stock">
<s:GetStockPriceResponse>
<s:Price>100.50</s:Price>
</s:GetStockPriceResponse>
</soap:Body>
</soap:Envelope>
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A SOAP message body defined within the WSDL message construct
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SOAP over HTTP
HTTP is the most common transport used to exchange SOAP messages.
SOAP-over-HTTP is a natural match with SOAP's RPC (request-response)
conventions because HTTP is a request-response-based protocol.
The SOAP request message is posted to the HTTP server with the HTTP
request, and the server returns the SOAP response message in the
HTTP response
HTTP request and HTTP response messages that contain a SOAP
message
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SOAP over HTTP
HTTP request containing a SOAP message :
POST /StockQuote HTTP/1.1
Content-Type: text/xml
Content-Length: nnnn
SOAPAction: "urn:StockQuote#GetQuote"
<s:Envelope xmlns:s="http://www.w3.org/2001/06/soap-envelope">
...
</s:Envelope>
HTTP response containing a SOAP message :
HTTP/1.1 200 OK
Content-Type: text/xml
Content-Length: nnnn
<s:Envelope xmlns:s="http://www.w3.org/2001/06/soap-envelope">
...
</s:Envelope>
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Service provider consisting of message processing and business
logic
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Revised service provider model now including an endpoint within the message processing logic
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Apache Axis
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Web Services Development using SOAP
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JAX-WS annotations to implement SOAP based
WS
Contract first approach using WSDL( Top down approach/ Reverse engineering)
It is a useful approach in case of generating web service implementation from the
contract/WSDL/interface doc.
Code first approach(bottom up approach/forward engineering)
It is a useful approach in case of legacy applications to expose it as web service.
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Web service
Implementations
Using annotations:
Annotate class/interface as @Webservice
Eg:
@Webservice
class FinnancialService{
}
Annotating web service operations
@Webservice
class FinnancialService{
@Webmethod
public List<Amount> convertToUSD( ArrayList<AmountInFC> a);
}
Note: Most of the WSDL documents elements and its attributes
values can be replaced by the annotations
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Publishing Endpoint of the Web
service
import javax.xml.ws.Endpoint;
public class Ep {
public static void main(String args[]){
Endpoint.publish("http://localhost:12345/cal", new Cal());
}
}
Note: Create the java project
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Generating stubs of the web service us
wsimport
wsimport is used to generate stubs of the web service using its WSDL
Document
Eg:
wsimport options
http://ravindras-macbook-air-10.local:8080/WS51/Cal?wsdl
To get the .java classes
wsimport -keep -s src
http://ravindras-macbook-air-10.local:8080/WS51/Cal?wsdl
wsimport -keep -d abc
http://ravindras-macbook-air-10.local:8080/WS51/Cal?wsdl
wsimport -quit http://ravindras-macbook-air-10.local:8080/WS51/Cal?wsdl
wsimport -s src -p edu.tvti
http://ravindras-macbook-air-10.local:8080/WS51/Cal?wsdl
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Implementation of Web client
program
Create ja ava project
Generate the stubs using wsimport
Keep the stubs in the java project in the corresponding package
public class WS51Client {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
Cal_Service cs= new Cal_Service();
System.out.println(cs.getCalPort().add(40, 400));
System.out.println(cs.getCalPort().hello("Babu"));
}
}
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Web Services Implementation
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Web Services Implementation
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Web Services Implementation
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Web Services Implementation
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Web Services Implementation
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Web Services Implementation
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Web Services Implementation
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High level relationship between first and second
generation
Describes the service for
uses uses
UDDI
is accessed using
Describes the service for
SOAP
enables discovery of
binds to uses
BPEL4WS for
xt
o nte str
at es
uses
esc c h e
Provides proto n ag or WSDL
col for Ma E
tra nabl
ns e d
ac is
WS-Coordination tio tri enables communication between
n s bu
f o t ed
r
describes
t
tex
Provides proto co n Provides guaranteed delivery for
col for es
a nag
M
f or Web Services
WS-Transaction
of
bi es
Pr
l i a ov
en ovi
y
li t
re pr
d de
se s e
Im
cu n s
ri t d -t
y govern WS-Reliable
fo o -
r
messaging
WS-Security WS-Policy
es
es
us
us
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REST Services
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JAX-RS
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Restful Services
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Creating Restful Service
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Restful Service -web.xml
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RESTful Service - Java Code
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Creating Restful Service
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Restful-client
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Restful-client
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QUESTIONS PLEASE
