There are many types of web services that have evolved over time. Some of the more prominent ones are as follows:
- Simple Object Access Protocol (SOAP)
- Universal Description, Discovery, and Integration (UDDI)
- Web Services Description Language (WSDL)
- Representational State Transfer (REST)
Out of these, SOAP became popular in the early 2000s, when XML riding on a high wave. The XML data format is used by various distributed systems to communicate with each other.
A SOAP request usually consists of these three basic components:
- The envelope
- The header
- The body
Just to perform an HTTP request and response cycle, we have to attach a lot of additional data in SOAP. A sample SOAP request to a fictional book server, www.example.org, looks like this:
POST /Books HTTP/1.1
Host: www.example.org
Content-Type: application/soap+xml; charset=utf-8
Content-Length: 299
SOAPAction...