58 lines
3.4 KiB
Go
58 lines
3.4 KiB
Go
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// muxado is an implementation of a general-purpose stream-multiplexing protocol.
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//
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// muxado allows clients applications to multiplex a single stream-oriented connection,
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// like a TCP connection, and communicate over many streams on top of it. muxado accomplishes
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// this by chunking data sent over each stream into frames and then reassembling the
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// frames and buffering the data before being passed up to the application
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// layer on the other side.
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//
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// muxado is very nearly an exact implementation of the HTTP2 framing layer while leaving out all
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// the HTTP-specific parts. It is heavily inspired by HTTP2/SPDY/WebMUX.
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//
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// muxado's documentation uses the following terms consistently for easier communication:
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// - "a transport" is an underlying stream (typically TCP) over which frames are sent between
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// endpoints
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// - "a stream" is any of the full-duplex byte-streams multiplexed over the transport
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// - "a session" refers to an instance of the muxado protocol running over a transport between
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// two endpoints
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//
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// Perhaps the best part of muxado is the interface exposed to client libraries. Since new
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// streams may be initiated by both sides at any time, a muxado.Session implements the net.Listener
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// interface (almost! Go unfortunately doesn't support covariant interface satisfaction so there's
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// a shim). Each muxado stream implements the net.Conn interface. This allows you to integrate
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// muxado into existing code which works with these interfaces (which is most Golang networking code)
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// with very little difficulty. Consider the following toy example. Here we'll initiate a new secure
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// connection to a server, and then ask it which application it wants via an HTTP request over a muxado stream
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// and then serve an entire HTTP application *to the server*.
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//
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//
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// sess, err := muxado.DialTLS("tcp", "example.com:1234", new(tls.Config))
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// client := &http.Client{Transport: &http.Transport{Dial: sess.NetDial}}
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// resp, err := client.Get("http://example.com/appchoice")
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// switch getChoice(resp.Body) {
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// case "foo":
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// http.Serve(sess.NetListener(), fooHandler)
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// case "bar":
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// http.Serve(sess.NetListener(), barHandler)
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// }
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//
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//
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// In addition to enabling multiple streams over a single connection, muxado enables other
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// behaviors which can be useful to the application layer:
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// - Both sides of a muxado session may initiate new streams
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// - muxado can transparently run application-level heartbeats and timeout dead sessions
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// - When connections fail, muxado indicates to the application which streams may be safely retried
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// - muxado supports prioritizing streams to maximize useful throughput when bandwidth-constrained
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//
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// A few examples of what these capabilities might make muxado useful for:
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// - eliminating custom async/pipeling code for your protocols
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// - eliminating connection pools in your protocols
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// - eliminating custom NAT traversal logic for enabling server-initiated streams
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//
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// muxado has been tuned to be very performant within the limits of what you can expect of pure-Go code.
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// Some of muxado's code looks unidiomatic in the quest for better performance. (Locks over channels, never allocating
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// from the heap, etc). muxado will typically outperform TCP connections when rapidly initiating many new
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// streams with small payloads. When sending a large payload over a single stream, muxado's worst case, it can
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// be 2-3x slower and does not parallelize well.
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package muxado
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