Kemal BaykalRasim Ismayilov

Web Services(1)A software system which connects the

machines over a network in an interoperable manner

The main idea is to make the communication between business systems and clients and also within each other.

The main advantage of Web services is to allow organizations to communicate data without knowing each other's IT systems behind the firewall.

Web Services(2)Does not provide GUI unlike the server/client

systems.Share business logic, data and processes

through a programmatic interfaceNormally the applications interact with each

other, not with usersBut you can add a GUI to gain extra

functionalities over the users.

Applications in Web ServicesXML is used to tag

the dataSOAP is used to

transfer the dataWSDL is used for

describing the services available

UDDI is used for listing which services are available

XML (Extensible Markup Language)It is classified as an extensible language

because it allows its users to define their own tags

Main purpose is to facilitate the sharing of structured data across different information systems

It is the language both machines and human beings can understand easily

It is used both to encode documents and serialize data

SOAP (Service Oriented Architecture Protocol)is a protocol for exchanging XML-based

messages over computer networksused to encode the information in Web

service request and response messages before sending them over a network

SOAP messages are independent of any operating system or protocol

may be transported using a variety of Internet protocols, including SMTP, MIME, and HTTP

SOAP elementsEnvelope element, identifies the XML

document as a SOAP message (required) Header element, contains header

information (optional)Body element, contains call and response

information (required)Fault element, provides information about

errors that occurred while processing the message (optional)

SOAP’s ProtocolsSOAP uses SMTP and

HTTP as an application layer protocol for transport.

HTTP is used more because it works well with today's Internet infrastructure.

SOAP works well with network firewalls.

SOAPAdvantages DisadvantagesSOAP allows the use of

different transport protocols.

Using SOAP allows easier communication behind proxies and firewalls

Because of the verbose XML format, SOAP can be considerably slower than technologies such as CORBA. This is not the case when only small messages are sent

Many SOAP implementations limit the amount of data that can be sent.

WSDL (Web Services Description Language)an XML-based language that provides a

model for describing Web servicesdescribe Web service's capabilities as

collections of communication endpoints capable of exchanging messages

an integral part of UDDI and the language that UDDI uses

is used to describe what a web service can do, where it resides, and how to call it

WSDL’s elements (1)Types : a container for data type definitions

using some type system Message: an abstract, typed definition of the

data being communicatedOperation: an abstract description of an

action supported by the servicePort Type: an abstract set of operations

supported by one or more endpoints

WSDL’s elements (2)Binding: a concrete protocol specification

for a particular port typePort: a single endpoint defined as a

combination of a binding and a network address

Service: a collection of related endpoints

WSDL’s Propertiesis a template for how services should be

described and bound by clientsis often used in with SOAP and XML Schema

to provide web services over the InternetA client program connecting to a web service

can read the WSDL to determine what functions are available on the server

was developed by Microsoft and IBM

UDDI (Universal Description, Discovery and Integration)

a Web-based distributed directory that enables businesses to list themselves on the Internet and discover each other

is platform independentis XML baseddesigned to be interrogated by SOAP

messagesto provide access to WSDL documents

describing the protocol bindings and message formats

UDDI ComponentsWhite Pages:

address, contact, and known identifiers

Yellow Pages: industrial categorizations based on standard taxonomies

Green Pages: technical information about services exposed by the business

UDDI Data TypesbusinessEntity: The top level structure,

describing a business or other entity for which information is being registered

bindingTemplate: Information necessary to use specific services which may have bindings to one or more protocols..

businessService: Description of a set of services which may contain one or more bindingTemplates.

tModel: Technical “finger print” for a given service which may also function as namespace to identify other entities

Additional Specifications for WS (1)WS SecurityWS ReliabilityWS Reliable

MessagingWS AddressingWS Transaction

Additional Specifications for WS (2)They are all specified by OASIS community

(Microsoft, IBM, VeriSign and Forum Systems)They use different technology (xml) not like

traditional httpSo the technology for security, reliable

messaging, reliability, addressing and transactions differ. They are XML based.

For example, as an alternative to use HTTPS to secure the channel, it uses XML based technologies such as XML Signature, XML Encyription,...

Web Services vs Java RMIWeb Services Java RMIinteroperabletransfer by xml files

(knowing what goes in wire)

easy access of enterprise business operations

platform-independent, easy interaction through different applications

needs large bandwidths

better performancetransfer by bytes integrated with Javaless CPU&memory usagedoesn’t need large

bandwidths

Alternative Solution!dual technology can

be usedWeb Service

implementation for external users

an alternative higher performance variant of internal use by Java RMI

Referenceshttp://www.ribomation.com/riboutils/

webservices-performance/article.htmlhttp://mercury.it.swin.edu.au/ctg/AWSA04/

Papers/gray.pdfhttp://en.wikipedia.org/wiki/Web_servicehttp://www.webopedia.com/TERM/W/

Web_services.html