semantic web services

M I R G H A N I A H M E D

S U D A N U N I V E R S I T Y- W E B T E C H N O L O G Y

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PA RT ( 1 )

Semantic Web Services

[email protected] - Sudan- 0917598234

Outlines

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What are web services?

Why we use web services?

The basics of web services

Securing web services.

What’s next for web services?


Definition

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Web services are software applications that can be

discovered, described, and accessed based on XML and

standard Web protocols over intranets, extranets , and the

Internet.


Scenario of Web Services In Use

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Why We Use Web Services?

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These questions are so fundamental that you should ask

them about any candidate Technology:

Do Web services solve real problems?

Is there really a future for Web services?

How can I use Web services?


Basics of Web Services

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This section gives a high-level overview of some of the

basic Web services technologies:

SOAP

WSDL


What Is SOAP?

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SOAP used to stand for “Simple Object Access Protocol”.

SOAP is the envelope syntax for sending and receiving XML messages with Web services.

SOAP is the communication language of Web services.

A SOAP message contains the following

elements:• A SOAP envelope that wraps the message

• A description of how data is encoded

• A SOAP body that contains the application-specific message that the backend application will understand.


Structure of a Web-based SOAP message

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What Is WSDL?

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Stand of Web Service Definition Language.

The W3C defines WSDL as “an XML format for

describing network services as a set of endpoints

operating on messages containing either document-

oriented or procedure oriented information.”


WSDL process works

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Dynamic communication by inspecting WSDL.


How to Discover Web Services

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if you would like to search for Web services based on the

features they provide and then dynamically connect to

them and use them, you will need a Web service registry.

two key registry technologies:

• UDDI.

• ebXML registries.


What Is UDDI?

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Universal Description, Discovery, and Integration is an

evolving technology and is not yet a standard, but it is

being implemented and embraced by major vendors.

UDDI is a phone book for Web services.

allows you to discover Web services.


UDDI Registry

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A UDDI Registry as a conceptual phone book


What Are ebXML Registries?

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The ebXML standard was created by OASIS to link

traditional data exchanges to business applications to

enable intelligent business processes using XML.


An ebXML Architecture

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An ebXML architecture in use.


Orchestrating Web Services

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Orchestration is the process of combining simple web

services to create complex, sequence-driven tasks.

A Simple Example:

• For our example, we’ll list five separate Web services within a

fictional organization:

Hotel finder Web service.

Driving directions finder.

Airline ticket booker.

Car rental Web service.

Expense report creator.


An Orchestration

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An orchestration example.


Securing Web Services

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One of the biggest concerns in the deployment of Web

services today is security.

One of the reasons that many system integrators appreciate

Web services is that SOAP rides on a standard protocol.

List basic terms that are related to Web services security:

• Authentication.

• Authorization.

• Single sign-on (SSO).

• Confidentiality.

• Integrity.

• Non repudiation.


Protection scenario

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Protection at every point


Other Security Types

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XML Signature

XML Signature is a W3C Recommendation that

provides a means to validate message integrity and non-

repudiation. With XML Signature, any part of an XML

document can be digitally signed.


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XML Encryption

XML Encryption is a technology and W3C Candidate

Recommendation that handles confidentiality; it can hide

sensitive content, so that only the intended recipient can

read the sensitive information.


What’s Next for Web Services?

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As Web services evolve, there is great potential in two

major areas:

Grid-Enabled Web Services:

Grid computing is a technology concept that can achieve

flexible, secure, and coordinated resource sharing among

dynamic collections of individuals, institutions , and

resources.


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A Semantic Web of Web Services:

The Semantic Web and Web services go hand in hand.

XML, a self-describing language, is not enough. WSDL, a

language that describes the SOAP interfaces to Web

services, is not enough. Automated support is needed in

dealing with numerous specialized data formats.


Summary

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Defining web services.

Basic technologies of web services.

Orchestration.

Security in web services.

A vision of where we believe web services will be

tomorrow.


References

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The Semantic Web:A Guide to the Future of XML, Web Services,

and Knowledge Management.

Dieter Fensel , “Semantic Enabled Web Services,” XML-Web

Services ONE Conference, June 7,2002.

Foster, Kesselman , Tuecke , “The Anatomy of the Grid:

Enabling Scalable Virtual Organizations,” International J.

Supercomputer Applications 15, no.3, (2001).

Kevin T. Smith, “Solutions for Web Services Security.

Bruce Schneier, “Cryptogram Monthly Newsletter,” February 15,

2002, http://www.counterpane.com


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