According to the W3C, a Web service is a software system designed to
support interoperable machine-to-machine interaction over a network.
It has an interface that is described in a machine-processable format
such as WSDL (Web Services Description Language). Other systems interact
with the Web service in a manner prescribed by its interface using messages.
WSDL is a language for describing how to interface with XML-based services.
Numerous XML standards have emerged that provide structure to the content
exchanged by applications. Such content can be sent and received over
a variety of transport protocols. To invoke a service, a consuming application
must know the service’s interface, including how to structure content
and which transport protocol to use. WSDL explicitly describes this interface
in a standardized, machine-readable format fit for analysis by tools.
WSDL is often used in combination with SOAP (Simple Object Access Protocol)
and XML Schema to provide web services over the internet. A client program
connecting to a web service can read the WSDL to determine what functions
are available on the server. Any special datatypes used are embedded
in the WSDL file in the form of XML Schema. The client can then use SOAP
to actually call one of the functions listed in the WSDL.
Messages are typically conveyed using HTTP, and normally comprise XML
in conjunction with other Web-related standards. 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 enables Compsoft to build applications that communicate with every
system they need to, rather than building an isolated application that
requires manual or batched updates on a regular basis.