SlackBuildsOrg/development/gsoap

The gSOAP toolkit provides a cross-platform software development
toolkit for C and C++ server and client Web service applications, and
simplifies the overall use of XML in any type of application. The
toolkit supports SOAP 1.1/1.2 RPC encoding and document/literal
styles, WSDL 1.1, MTOM/MIME/DIME attachments (streaming), SOAP-over-
UDP, request-response and one-way messaging. The toolkit also supports
WS-Addressing and WS-Security, with several other WS-* available
or under development.

Note this will not build in parallel; set MAKEFLAGS="-j1" if you have
problems.