Apache AXIS is an implementation of the SOAP ("Simple Object Access Protocol") submission to W3C.

From the draft W3C specification:

SOAP is a lightweight protocol for exchange of information in a decentralized, distributed environment. It is an XML based protocol that consists of three parts: an envelope that defines a framework for describing what is in a message and how to process it, a set of encoding rules for expressing instances of application-defined datatypes, and a convention for representing remote procedure calls and responses.

This project is a follow-on to the Apache SOAP project.