It is an extension that is bundled with Dreamweaver CC to replace the server behaviors functionality that Adobe removed:
http://www.webassist.com/tutorials/Server-behaviors-for-Dreamweaver-Creative-Cloud
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.