There are a number of web services that use markup languages

There are a number of web services that use markup languages. For testing purpose and for our this

 "Api Testing step by step tutorial" 

 We are going to use only REST. 

1.1.JSON-RPC
2.JSON-WSP
3.Web template
4.Web Services Description Language (WSDL) from the W3C
5.XML Interface for Network Services (XINS) provides a POX-style Web service specification format
6.Web Services Conversation Language (WSCL)
7.Web Services Flow Language (WSFL) (superseded by BPEL)
8.WS-MetadataExchange
9.Representational state transfer (REST) versus remote procedure call (RPC)