The WebSocket Protocol - The Definitive Guide to HTML5 WebSocket - page 37

the client to the server. A WebSocket server can also act as a WebSocket client. However,
with WebSocket, web clients like browsers cannot accept connections that they did not
initiate. Figure 3-3 shows WebSocket clients connected to a server, where either the client
or the server can send data at any time.

Figure 3-3. WebSocket clients connected to a server

WebSocket bridges the world of the Web and the world of the Internet (or more
specifically, TCP/IP). Asynchronous protocols that were not previously easy to use with
web applications can now easily communicate using WebSocket. Table 3-1 compares the
main areas of TCP, HTTP, and WebSocket.

Table 3-1. Comparison of TCP, HTTP, and WebSocket
Feature TCP HTTP WebSocket

Addressing IP address and port URL URL

Simultaneous transmission Full duplex Half duplex Full duplex

Content Byte streams MIME messages Text and binary

messages

Message boundaries No Yes Yes

Connection oriented Yes No Yes