From Wikipedia:
A Web service is a method of communication between two electronic devices over the World Wide Web. A Web service is a software function provided at a network address over the web or the cloud, it is a service that is “always on” as in the concept of utility computing.
Probably the most common use today of web services in a B2B or systems integration environment is Extensible Markup Language (XML), Standard Object Access Protocol (SOAP), and Web Services Definition Language (WSDL) *.
And then along came Web 2.0 and AJAX
Before AJAX, web pages were either static or reloaded if the contents needed to be changed. With AJAX, web applications could create a dialogue between the client and the server, with just portions of the ‘page’ being updated with new data. As revolutionary as this was, it still used XML, which was both verbose and needed to be parsed.
Enter JSON, which took Web 2.0 to a whole new level: faster, thinner, quicker and easier to parse (even addressable).
Today, most web applications being developed use AJAX and JSON.
However, it should also be noted that many other data formats can be used in this new AJAX paradigm; simple text, CSV, Pipe delimited — just to name a few.
*SOAP is sort of a virtual envelope for computer code that acts like an introductory letter, saying what’s inside and where it should go. And WSDL is the nifty little code that allows different types of software talk to directly each other.
