What is SOAP?

Before we can learn about Web Services, we need to talk about SOAP.

SOAP stands for the Simple Object Access Protocol. (This is interesting because SOAP is not simple and does not allow you to access objects per se. It is a protocol, however!)

SOAP is an HTTP-based protocol that allows applications to invoke remote procedure calls across the Internet. SOAP uses XML to encode requests and their subsequent responses.

A SOAP client is any application or piece of software that initiates a SOAP request. A SOAP server is the software that responds to the request. SOAP requests are handled initially by a web (HTTP) server that then passes the request on to a SOAP server.