From 1b863c350ba1f9b8ad1cb458df514ab0fe6bb127 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Lo=C3=AFc=20Hoguin?= Date: Mon, 11 Dec 2017 11:27:17 +0100 Subject: Add documentation for Cowboy 2.2 --- docs/en/cowboy/2.2/guide/ws_protocol/index.html | 229 ++++++++++++++++++++++++ 1 file changed, 229 insertions(+) create mode 100644 docs/en/cowboy/2.2/guide/ws_protocol/index.html (limited to 'docs/en/cowboy/2.2/guide/ws_protocol') diff --git a/docs/en/cowboy/2.2/guide/ws_protocol/index.html b/docs/en/cowboy/2.2/guide/ws_protocol/index.html new file mode 100644 index 00000000..328eaa74 --- /dev/null +++ b/docs/en/cowboy/2.2/guide/ws_protocol/index.html @@ -0,0 +1,229 @@ + + + + + + + + + + + + Nine Nines: The Websocket protocol + + + + + + + + + + + + + + +
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The Websocket protocol

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This chapter explains what Websocket is and why it is +a vital component of soft realtime Web applications.

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Description

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Websocket is an extension to HTTP that emulates plain TCP +connections between the client, typically a Web browser, +and the server. It uses the HTTP Upgrade mechanism to +establish the connection.

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Websocket connections are fully asynchronous, unlike +HTTP/1.1 (synchronous) and HTTP/2 (asynchronous, but the +server can only initiate streams in response to requests). +With Websocket, the client and the server can both send +frames at any time without any restriction. It is closer +to TCP than any of the HTTP protocols.

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Websocket is an IETF standard. Cowboy supports the standard +and all drafts that were previously implemented by browsers, +excluding the initial flawed draft sometimes known as +"version 0".

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Websocket vs HTTP/2

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For a few years Websocket was the only way to have a +bidirectional asynchronous connection with the server. +This changed when HTTP/2 was introduced. While HTTP/2 +requires the client to first perform a request before +the server can push data, this is only a minor restriction +as the client can do so just as it connects.

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Websocket was designed as a kind-of-TCP channel to a +server. It only defines the framing and connection +management and lets the developer implement a protocol +on top of it. For example you could implement IRC over +Websocket and use a Javascript IRC client to speak to +the server.

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HTTP/2 on the other hand is just an improvement over +the HTTP/1.1 connection and request/response mechanism. +It has the same semantics as HTTP/1.1.

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If all you need is to access an HTTP API, then HTTP/2 +should be your first choice. On the other hand, if what +you need is a different protocol, then you can use +Websocket to implement it.

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Implementation

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Cowboy implements Websocket as a protocol upgrade. Once the +upgrade is performed from the init/2 callback, Cowboy +switches to Websocket. Please consult the next chapter for +more information on initiating and handling Websocket +connections.

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The implementation of Websocket in Cowboy is validated using +the Autobahn test suite, which is an extensive suite of tests +covering all aspects of the protocol. Cowboy passes the +suite with 100% success, including all optional tests.

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Cowboy’s Websocket implementation also includes the +permessage-deflate and x-webkit-deflate-frame compression +extensions.

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Cowboy will automatically use compression when the +compress option is returned from the init/2 function.

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