Zato is an open-source ESB and application server written in Python. It is designed to integrate systems in SOA and to build backend applications (i.e. API only).

Client-server applications flourished for only a brief period but they created a new generation of easy-to-use, graphical applications that delivered computing to hundreds of thousands of small ...

It describes how to develop an application client that references multiple web services that implement any combination of the two web services programming models.