Websockets

The WebSocket protocol is a technology that enables bidirectional, full-duplex communication between client and server over a persistent, single-socket connection. Websockets have broad applicability, and are an excellent choice for architecting event-driven systems and building realtime apps and services where it’s essential for data to be delivered immediately. 

Ably supports client connections over multiple transports. The WebSocket transport is the primary transport for efficient connection by browser clients that are websocket-capable, and any other client environment that offers direct TCP socket access.