The Free On-line Dictionary of Computing (30 December 2018):

Simple Object Access Protocol

    (SOAP) A minimal set of conventions for invoking
   code using XML over HTTP.

   DevelopMentor, Microsoft Corporation, and UserLand
   Software submitted SOAP to the IETF as an internal draft in
   December 1999.

   (http://w3.org/TR/SOAP/).

   (2000-01-08)