BOSH (protocol)
Bidirectional-streams Over Synchronous HTTP (BOSH) is a transport protocol that emulates a bidirectional stream between two entities (such as a client and a server) by using multiple synchronous HTTP request/response pairs without requiring the use of polling or asynchronous chunking. For applications that require both "push" and "pull" communications, BOSH is significantly more bandwidth-efficient and responsive than most other bidirectional HTTP-based transport protocols and AJAX. BOSH achieves this by avoiding HTTP polling, yet it does so without resorting to chunked HTTP responses as is done in the technique known as Comet.