WEB SERVICES: THE NEW WAVE OF WEB

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Nov 5, 2013 (4 years and 3 days ago)

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WEB SERVICES: THE NEW WAVE OF WEB
TECHNOLOGY

Wafa Khorsheed, Eastern Michigan University

Asad Khailany, Eastern Michigan University

Outline

I.
Introduction

II.
Definition Of Web Services

III.
Web Services Architecture

IV.
Web Service Operations

V.
Example Application Of Web Services

VI.
WSDL Partial definition of GetCatalog Service

VII.
Benefits Of Web Services

Introduction


Business organizations have embraced the Internet and Web
Technology as soon as they discovered the create value of the
Web for conducting business.


The Internet presented incredible value and reach for businesses
of all sizes.


Great efficiencies, cost reduction and new business opportunities
have led the way for organization to use this technology.


This type of technology is commonly referred to as service
-
centric computing. Service
-
centric application require the
integration of many collaborating applications on the Internet to
achieve a business functionality

Definition Of Web Services


self
-
contained, self
-
describing, modular applications that can be
published, located, and invoked across the Web.



Web Services is any program that is callable by another program
across the web in a platform/language/object model
independent manner, using standard web protocols (XML,
SOAP, WSDL, UDDI, etc.)



There are three main uses of Web services.


Application integration


Business integration



Commercial Web services

Web Services Architecture


Service providers:

Provide services, and maintain a
registry that makes those services available.



Service requestors:

Work with service brokers to
discover Web services, then invoke those services to
create applications.



Service brokers:
they are the clearinghouses for
services. Service brokers act as matchmakers between
service providers and service requestors. The services
broker is referred to as UDDI (Universal Discovery,
Description and Integration).


Web Service Operations


Publish/Unpublish
: Publishing and unpublishing involves
advertising services to a registry (publishing) or removing those
entries (unpublishing). The service provider contacts the service
broker to publish or unpublish a service.



Find
: The find operation is performed by service requestors and
service brokers together. The service requestors describe the
kinds of services they're looking for, and the service brokers
deliver the results that best match the request.



Bind
: The bind operation takes place between the service
requestor and the service provider. The two parties negotiate as
appropriate so the requestor can access and invoke services of
the provider.


Web Services Architecture


DB2

COBOL

app

z
-
Series Mainframe

WebSphere


with EJBs

Web Services

Requestor

Windows 2000



Web

app

server


COM

app

COM

app

CORBA

app

Web service
Provider

SOAP Messages

WSDL

Web Services Broker

(UDDI)



Example Application: Purchase Order


Customer

Supplier

Carrier

Warehouse

GetCatalog()

SendPO()

GetPOStatus()

GetInvoice()

ShipRequest()

ShipConfirm()

ShipOrder()

Bank

CheckAccBalance()

DebitAccount()

WSDL Partial definition of GetCatalog Service


<binding name="PartOrderingServiceBinding"


type="GetCatalogServiceType">


<soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/>


<operation name="GetCatalog">


<soap:operation soapAction="http://www.PartOrdering.com/GetCatalog"/>


<input>


<soap:body type="InMessageRequest"


namespace="urn:PartOrdering"


encoding="http://schemas.xmlsoap.org/soap/encoding/"/>


</input>


<output>


<soap:body type="OutMessageResponse"


encoding="http://schemas.xmlsoap.org/soap/encoding/"/>


</output>


</operation>

</binding>

Benefits Of Web Services


Promote interoperability:


Enable just
-
in
-
time integration:



Reduce complexity through encapsulation.


Give new life to legacy applications: