HTTP Adapter

The HTTP adapter is used to exchange information between Microsoft BizTalk Server and an application by means of the HTTP protocol. The HTTP adapter consists of two adapters—a receive adapter and a send adapter. The HTTP receive adapter is a Microsoft Internet Information Services (IIS) Internet Server Application Programming Interface (ISAPI) extension that the IIS process hosts, and it controls the receive locations that use the HTTP adapter. The HTTP send adapter controls the send ports that use the HTTP adapter.

Source: Microsoft