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Web ServicesSubmited By:Miss.Rachna Kamalia

Prepared By:Miss.Nilam Radadiya(Roll No:33) &Miss.Kinjal Kapadiya(Roll No:16)

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What is Web Services? How it Works. Why use Web Services. Web Services Components Web Service Model Advantages Disadvantages Conclusion References

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A web service is a collection of open protocols and standards used for exchanging data between applications or systems.

It support machine-to-machine interactions over the It support machine-to-machine interactions over the network.network.

Basic ideas is to build anBasic ideas is to build an platform and programming platform and programming language-independent distributed invocation system out of language-independent distributed invocation system out of existing Web standards.existing Web standards.

Most standards defined by W3C.Most standards defined by W3C.

What is a Web Service?

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Very loosely defined, when compared toVery loosely defined, when compared to CORBA CORBA(Common (Common object request broker architecture).object request broker architecture).

Inherit both good and bad of the web services.Inherit both good and bad of the web services.◦ Scalable, simple, distributedScalable, simple, distributed◦ But But no centralized managementno centralized management system is inefficient, must be system is inefficient, must be

tolerant of failures.tolerant of failures.

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How does a web services work?

- The client sends a request

- Request encoded in XML

- Function (GET, POST…) in the file

- The server decodes the file

- The function is executed

- A new XML file is encoded

and re-send to the client. - Clients and servers communicate over the HyperText Transfer Protocol (HTTP).

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Web services provide a clean separation between a capability and its user interface.

This allows a company (Google) with a sophisticated capability and amounts of data to make that capability available to its partners.

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Why use web Services?

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XML stands for EXtensible Markup Language.

XML is a markup language much like HTML. XML was designed to describe data.

XML tags are not predefined. You must define your own tags.

The prefect choice for enabling cross-platform data communication in Web Services.

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XML Concept

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Web Services Description Language(WSDL)

Defines what your service does and how it is invoked.

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WSDL stands for Web Services Description Language

WSDL is an XML based protocol for information exchange in decentralized and distributed environments.

WSDL is the standard format for describing a web service.

WSDL definition describes how to access a web service and what operations it will perform.

WSDL is a language for describing how to interface with XML-based services.

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WSDL overview

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WSDL is an integral part of UDDI, an XML-based worldwide business registry.

WSDL is the language that UDDI uses. WSDL was developed by Microsoft and IBM.

Elements of WSDL:

<types> A container for data type definitions used by the web

service

WSDL( Continue…)Web Services

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<message> A typed definition of the data being communicated.

<port Type> A set of operations supported by one or more

endpoints.

<binding> A protocol and data format specification for a

particular port type

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WSDL( Continue…)

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Simple Object Access Protocol(SOAP)

A message format for exchanging structured, typed information

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SOAP stands for Simple Object Access Protocol.

SOAP is a protocol for accessing web services.

SOAP is based on XML.

SOAP provides a way to communicate between applications running on different operating systems, with different technologies and programming languages.

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SOAP

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SOAP has three major characteristics:

Extensibility – security and WS-routing are among the extensions under development.

Neutrality - SOAP can be used over any transport protocol such as HTTP, SMTP or even TCP.

Independent - SOAP allows for any programming model .

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SOAP Charactristics

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UDDI is a platform-independent framework for describing services, discovering businesses, and integrating business services by using the Internet.

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.

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UDDI Overview

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The Web Services architecture is based upon the interactions between three roles:

◦ Service provider◦ Service registry◦ Service requestor

The interactions involve the:◦ Publish operations◦ Find operation◦ Bind operations.

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Web service model

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The web services model follows the publish, find and bind paradigm.

Web ServiceRegistry

Web Serviceprovider

Web Service Client

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web service model(cont…)

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Interoperability - This is the most important benefit of Web Services. Web Services typically work outside of private networks.

usability - This gives your applications the freedom to chose the Web Services that they need. This allows you to develop services and/or client-side code using the languages and tools that you want.

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Advantages

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Reusability - Web Services provide not a component-based model of application development, but the closest thing possible to zero-coding deployment of such services.

Deployability - Web Services are deployed over standard Internet technologies.  

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Advantages(cont…)

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Distributed transactions: if the environment requires distributed transactions with

resources, it should be studied and tested with standard solutions based on BTP, WS-Transactions, and WS-Coordination.

Quality of Service (QoS):In case of a mission-critical solution, the service providers must examine the reliability and performance of the service in uncertain conditions for high availability.

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Disadvantages

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Security: Web services are exposed to the public using http-based protocols.

As Web services is publicly available, it must be implemented using authentication and authorization mechanisms and using SSL-enabling encryption of the messages for securing the usage.

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Disadvantages(cont…)

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This aimed to give an overview of recent progress in automatic Web services composition.

At first, we propose a three-step model for Web services composition process.

The composition model consists of service presentation,translation,process generation, evaluation and execution. Each step requires

different languages, platforms and methods. 

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Conclusion

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www.w3school.com www.webservices.org

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References

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