Software components that can be published,
located, and run over the Internet using
Extensible Markup Language (XML).
A web service is a software application that
works over the internet.
A web service is service-oriented application that
communicates over the web using messages
We can test the web service by using the local
Working of web service
The web service is also a software, with its own class
and methods .
A request by the client application constitutes
construction and sending a SOAP request using HTTP to
the web server.
For a web service to work, the computer has to be
connected to the internet.
The web server hosts the class and its methods of a web
service, for a client computer to request and use.
Any client computer located any where in the world, with
an internet connection can request and use the class and
its methods of the web service.
Web Service technologies
A web service is service-oriented
application that communicates over the web
1 . The Web
A Web service is a Web resource. It
communicates over the internet using standard
Web protocols. Leveraging the Web yields
universal connectivity and pervasiveness.
A web service is also hosted on a web server.
We can access a web service programmatically,
only programmatically and not by a browser.
2 . XML
XML is a language for electronic documents and
messages. It provides a universal, self-describing data
format that can be interpreted, processed, and
transformed by any application running on any platform.
Each bit of information in a document is defined by tags
without overload of formatting present in HTML.
This type of representation is suitable for application to
3 . SOA
SOA stands for service-oriented architecture.
SOA is a concept and describes a set of well-
Each pattern represents a mechanism to describe a
service, to advertise and discover a service, and to
communicate with a service.
Web services rely on these patterns and client
applications connect to a service using these patterns.
Service provider :-
Who develops or supplies the service.
Service consumer :-
Who uses the service.
Service broker :-
Facilitates the advertising and discovery process.
The service provider registers the service with a
The service broker gives the service consumer
directions on how to find the service and its service
The service consumer uses the contract to bind the
client to the service, at which point the client and service
3.3 . Standard
WSDL provides a mechanism to describe a Web
UDDI provides a mechanism to advertise and
discover a Web service.
SOAP provides a mechanism for clients and
services to communicate.
Simple Object Access Protocol (SOAP) is an XML
protocol. It is used by client applications to communicate
with Web services.
SOAP implements an envelope for sending an XML
message. We put an XML message into an envelope
and send it across the networks.
A SOAP envelope is transported by various
communication protocols. But, the most common way to
transfer SOAP messages is to use HTTP. Other Web
protocols commonly used are SMTP and FTP.
A SOAP message consists of two parts.
SOAP header :-
It includes system level
SOAP body :-
It contains the message
the information that is
Reason for why we use Web Services
Web Services operate on a service-based model
Web Services allow us to communicate among all
different entities without affecting their existence.
It is written separately from the application logic.
They improve the information flow between applications.
web services use text based protocol that all
applications can understand.
Web services reduce licensing costs.
They do not rely on special protocols.