Web Services
Different books and different organizations provide different definitions to Web Services. Some of
them are listed here.
A web service is any piece of software that makes itself available over the internet and uses a
standardized XML messaging system. XML is used to encode all communications to a web
service. For example, a client invokes a web service by sending an XML message, then waits
for a corresponding XML response. As all communication is in XML, web services are not
tied to any one operating system or programming language--Java can talk with Perl; Windows
applications can talk with Unix applications.
Web services are self-contained, modular, distributed, dynamic applications that can be
described, published, located, or invoked over the network to create products, processes, and
supply chains. These applications can be local, distributed, or web-based. Web services are
built on top of open standards such as TCP/IP, HTTP, Java, HTML, and XML.
Web services are XML-based information exchange systems that use the Internet for direct
application-to-application interaction. These systems can include programs, objects,
messages, or documents.
A web service is a collection of open protocols and standards used for exchanging data
between applications or systems. Software applications written in various programming
languages and running on various platforms can use web services to exchange data over
computer networks like the Internet in a manner similar to inter-process communication on a
single computer. This interoperability (e.g., between Java and Python, or Windows and Linux
applications) is due to the use of open standards.
To summarize, a complete web service is, therefore, any service that:
Is available over the Internet or private (intranet) networks
Uses a standardized XML messaging system
Is not tied to any one operating system or programming language
Is self-describing via a common XML grammar
Is discoverable via a simple find mechanism
Components of Web Services
The basic web services platform is XML + HTTP. All the standard web services work using the
following three major web service components.
SOAP (Simple Object Access Protocol)
UDDI (Universal Description, Discovery and Integration)
WSDL (Web Services Description Language)
SOAP
SOAP is an acronym for Simple Object Access Protocol.
SOAP is a XML-based protocol for accessing web services.
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SOAP is a W3C recommendation for communication between applications.
SOAP is XML based, so it is platform independent and language independent. In other words, it can
be used with Java, .Net or PHP language on any platform.
WSDL
WSDL is an acronym for Web Services Description Language.
WSDL is a xml document containing information about web services such as method name, method
parameter and how to access it.
WSDL is a part of UDDI. It acts as an interface between web service applications.
WSDL is pronounced as wiz-dull.
UDDI
UDDI is an acronym for Universal Description, Discovery and Integration.
UDDI is a XML based framework for describing, discovering and integrating web services.
UDDI is a directory of web service interfaces described by WSDL, containing information about web
services
Benefits of using Web Services:
Exposing the Existing Function on the network
A web service is a unit of managed code that can be remotely invoked using HTTP, that is, it can be
activated using HTTP requests. Web services allows you to expose the functionality of your existing
code over the network. Once it is exposed on the network, other application can use the functionality
of your program.
Interoperability
Web services allow various applications to talk to each other and share data and services among
themselves. Other applications can also use the web services. For example, a VB or .NET application
can talk to Java web services and vice versa. Web services are used to make the application platform
and technology independent.
Standardized Protocol
Web services use standardized industry standard protocol for the communication. All the four layers
(Service Transport, XML Messaging, Service Description, and Service Discovery layers) use well-
defined protocols in the web services protocol stack. This standardization of protocol stack gives the
business many advantages such as a wide range of choices, reduction in the cost due to competition,
and increase in the quality.
Low Cost of Communication
Web services use SOAP over HTTP protocol, so you can use your existing low-cost internet for
implementing web services. This solution is much less costly compared to proprietary solutions like
EDI/B2B. Besides SOAP over HTTP, web services can also be implemented on other reliable
transport mechanisms like FTP.
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