The crucial differences between pre-HTML5 communication methods and HTML5 WebSocket are located in the new HTML5 protocol. WebSocket protocol uses HTTP to establish a connection, but the subsequent communication is performed by the
WebSocket reader protocol. In addition, the feature header is very small, resulting in reduced communication overhead. Because a persistent connection is assumed, it is possible for clients and servers to remain in a connected state. Accordingly, it is necessary to update existing TCP servers to meet the new WebSocket specification. WebSockets are present in a variety of servers. These servers may be implemented in languages such as Java, Python, php, and Ruby. Table 1 provides descriptions for some selected WebSocket-enabled servers.