SOAP, WSDL, And Discovery

8/8/2019 SOAP, WSDL, And Discovery

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SOAP, WSDL, and

Discovery

Unit-4 C# & Dot NET Framework


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Web Services

Web services are application components

Web services communicate using open

protocols

Web services are self-contained and self-

describing

Web services can be discovered using UDDI

Web services can be used by other applications XML is the basis forWeb services


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How Does it works?

The basic Web services platform is XML +

HTTP.

XML provides a language which can beused between different platforms and

programming languages and still express

complex messages and functions.

The HTTP protocol is the most used

Internet protocol.


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Web services platform elements

SOAP (Simple Object Access Protocol)

UDDI (Universal Description, Discovery

and Integration) WSDL (Web Services Description

Language)


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Purpose

.NET Web Services expand on the concept of

distributed processing to build components

whose methods can be invoked across the

Internet. These components can be built in any

.NET language, and they communicate using

open protocols that are platform-independent.

W

eb Services takeW

eb-applications to the NextLevel


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Purpose

By using Web services, your applicationcan publish its function or message to therest of the world.

Web services use XML to code and todecode data, and SOAP to transport it(using open protocols).

WithWeb services you can exchange databetween different applications anddifferent platforms.


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Purpose

In such a world, a single application mightdraw on and stitch together the services ofhundreds of small web services

distributed all over the world. This takes the Web to an entirely new

dimension: not only is information

retrieved and exchanged, but alsomethods are invoked and applications areexecuted.


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Web Services have Two Types of Uses

Reusable application-components.

There are things applications need very often. So why

make these over and over again?

Web services can offer application-components like:currency conversion, weather reports, or even

language translation as services.

Connect existing software.

Web services can help to solve the interoperabilityproblem by giving different applications a way to link

their data.


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List ofWeb Services

The list of web services that might be useful todevelopers and end users seems boundless.

A bookstore might provide a web service thattakes an ISBN and returns the price andavailability of a title.

A hotel's web service might take a date rangeand number of guests and return a reservation.

Another web service might take a telephone

number and return a name and address. Yet another might provide information about the

weather or shuttle launches.


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.NET services

Microsoft has announced a number ofcommercial .NET services as part of its .NET MyServices initiative.

Among these are its Passport service foridentifying and authenticating users(http://www.passport.com/), as well as servicesfor managing storage, notification,

appointments, and a host of other applications. These services, as well as the ones you write,can be integrated with your applications just likeany other business object.


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What is needed to make web services possible

is a simple, universally accepted protocol for

exposing, finding, and invoking web service

functions. In 1999, Simple Object Access Protocol

(SOAP) was proposed to the World Wide

Web Consortium. SOAP has the advantages

of being based on XML and of using standard

Internet communications protocols.


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Why SOAP ?

It is important for application development to allowInternet communication between programs.

Today's applications communicate using RemoteProcedure Calls (RPC) between objects like DCOM and

CORBA, but HTTP was not designed for this. RPCrepresents a compatibility and security problem; firewallsand proxy servers will normally block this kind of traffic.

A better way to communicate between applications isoverHTTP, because HTTP is supported by all Internetbrowsers and servers. SOAP was created to accomplish

this. SOAP provides a way to communicate between

applications running on different operating systems, withdifferent technologies and programming languages


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SOAP

SOAP is an XML-based protocol to let applications exchangeinformation overHTTP.

Or more simple: SOAP is a protocol for accessing aWeb Service.

SOAP stands for Simple Object Access Protocol

SOAP is a communication protocol

SOAP is a format for sending messages SOAP is designed to communicate via Internet

SOAP is platform independent

SOAP is language independent

SOAP is based on XML

SOAP is simple and extensible SOAP allows you to get around firewalls

SOAP is a W3C standard


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SOAP

SOAP is a lightweight, message-based protocol built onXML, HTTP, and SMTP.

Two other protocols are desirable, but not required, for aclient to use a SOAP-enabled web service: a description of the methods provided by a particular service that

can be understood and acted upon by clients, and a

description of all such services available at a particular site orURL.

The first of these is provided in .NET by the Web Service

Description Language (WSDL) protocol, jointly developed byMicrosoft, IBM, and others.

Two other protocols have been proposed for discovery: UDDI, ajoint effort by a number of companies including IBM andMicrosoft, and Discovery, a proprietary offering from Microsoft.


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SOAP Building Blocks

A SOAP message is an ordinary XML document

containing the following elements:

An Envelope element that identifies the XML

document as a SOAP message

A Header element that contains header information

A Body element that contains call and response

information

A Fault element containing errors and status

information


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WSDL

WSDL is an XML schema used to describe theavailable methods and the interface of a webservice.

WSDL is an XML-based language for locatingand describing Web services.

WSDL stands forWeb Services DescriptionLanguage WSDL is based on XML

WSDL is used to describe Web services WSDL is used to locate Web services

WSDL is a W3C standard


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WSDL

A WSDL document is just a simple XML document.

It contains set of definitions to describe a web service.

The WSDL Document Structure

AW

SDL document describes a web service using thesemajor elements:

-The data types used by the webservice

The messages used by the web service

The operations performed by the web service

The communication protocols used by the webservice


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main structure of a WSDL

document definition of types........

definition of a message....

definition of a port.......

definition of a binding....


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UDDI

UDDI is a directory service where companiescan register and search forWeb services.

UDDI stands for Universal Description,

Discovery and Integration UDDI is a directory for storing information about

web services

UDDI is a directory of web service interfaces

described by WSDL UDDI communicates via SOAP

UDDI is built into the Microsoft .NET platform


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What is UDDI Based On?

UDDI uses WorldWideWeb Consortium (W3C)and Internet Engineering Task Force (IETF)Internet standards such as XML, HTTP, and

DNS protocols. UDDI uses WSDL to describe interfaces to web

services

Additionally, cross platform programming

features are addressed by adopting SOAP,known as XML Protocol messagingspecifications found at the W3CWeb site.


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UDDI Benefits

Any industry or businesses of all sizes can benefit from UDDI.

Before UDDI, there was no Internet standard for businesses to reach theircustomers and partners with information about their products and services.Nor was there a method of how to integrate into each other's systems andprocesses.

Problems the UDDI specification can help to solve:

Making it possible to discover the right business from the millions currentlyonline

Defining how to enable commerce once the preferred business isdiscovered

Reaching new customers and increasing access to current customers

Expanding offerings and extending market reach

Solving customer-driven need to remove barriers to allow for rapidparticipation in the global Internet economy

Describing services and business processes programmatically in a single,open, and secure environment


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How can UDDI be Used?

If the industry published an UDDI standardfor flight rate checking and reservation,airlines could register their services into an

UDDI directory. Travel agencies couldthen search the UDDI directory to find theairline's reservation interface. When theinterface is found, the travel agency can

communicate with the service immediatelybecause it uses a well-defined reservationinterface.


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Who is Supporting UDDI?

UDDI is a cross-industry effort driven by all

major platform and software providers like

Dell, Fujitsu, HP, Hitachi, IBM, Intel,

Microsoft, Oracle, SAP, and Sun, as well

as a large community of marketplace

operators, and e-business leaders.

Over 220 companies are members of theUDDI community.

SOAP, WSDL, And Discovery

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