The WebSocket Protocol is designed on the principle that there should be minimal framing (the only framing that exists is to make the protocol frame-based instead of stream-based and to support a distinction between Unicode text and binary frames). It is expected that metadata would be layered on top of WebSocket by the application Fette & Melnikov Standards Track [Page 9] RFC 6455 The WebSocket Protocol December 2011 layer, in the same way that metadata is layered on top of TCP by the application layer (e.g., HTTP). Conceptually, WebSocket is really just a layer on top of TCP that does the following: o adds a web origin-based security model for browsers o adds an addressing and protocol naming mechanism to support multiple services on one port and multiple host names on one IP address o layers a framing mechanism on top of TCP to get back to the IP packet mechanism that TCP is built on, but without length limits o includes an additional closing handshake in-band that is designed to work in the presence of proxies and other intermediaries Other than that, WebSocket adds nothing. Basically it is intended to be as close to just exposing raw TCP to script as possible given the constraints of the Web. It's also designed in such a way that its servers can share a port with HTTP servers, by having its handshake be a valid HTTP Upgrade request. One could conceptually use other protocols to establish client-server messaging, but the intent of WebSockets is to provide a relatively simple protocol that can coexist with HTTP and deployed HTTP infrastructure (such as proxies) and that is as close to TCP as is safe for use with such infrastructure given security considerations, with targeted additions to simplify usage and keep simple things simple (such as the addition of message semantics).

Screen and Tmux are used to add a session context to a pseudoterminal, making for a much more robust and versatile solution. For example, each provides terminal persistence, allowing a user to disconnect from one computer and then connect later from another computer.