Init.

Author: MathieuTurcotte

LICENSE

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+Copyright (C) 2013 Mathieu Turcotte
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+About
+=====
+
+This a server-side browser channel implementation written in Go.
+
+The client-side javascript implementation is provided by the
+[Google Closure Library](https://developers.google.com/closure/library/).
+
+Installing
+==========
+
+    $ go get github.com/MathieuTurcotte/go-browserchannel/bc
+
+Documentation
+=============
+
+Read it [online](http://go.pkgdoc.org/github.com/MathieuTurcotte/go-broswerchannel/bc) or run
+
+    $ go doc github.com/MathieuTurcotte/go-browserchannel/bc
+
+License
+=======
+
+This code is free to use under the terms of the [MIT license](http://mturcotte.mit-license.org/).

bc/backchannel.go

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+// Copyright (c) 2013 Mathieu Turcotte
+// Licensed under the MIT license.
+
+package bc
+
+import (
+	"io"
+	"log"
+	"net/http"
+	"strconv"
+)
+
+// The back channel interface shared between the XHR and HTML implementations.
+type backChannel interface {
+	getRequestId() string
+	isReusable() bool
+	setChunked(bool)
+	isChunked() bool
+	send(data []byte) (int, error)
+	discard()
+	wait()
+}
+
+// Common bookeeping information shared between the chunked XHR and HTML
+// variants.
+type backChannelBase struct {
+	sid       SessionId
+	rid       string
+	w         http.ResponseWriter
+	chunked   bool
+	bytesSent int
+	done      chan bool
+}
+
+func (b *backChannelBase) getRequestId() string {
+	return b.rid
+}
+
+func (b *backChannelBase) isReusable() bool {
+	return b.chunked && b.bytesSent < 10*1024
+}
+
+func (b *backChannelBase) setChunked(chunked bool) {
+	b.chunked = chunked
+}
+
+func (b *backChannelBase) isChunked() bool {
+	return b.chunked
+}
+
+func (b *backChannelBase) wait() {
+	<-b.done
+}
+
+// The chunked XHR back channel implementation.
+type xhrBackChannel struct {
+	backChannelBase
+}
+
+func (b *xhrBackChannel) send(data []byte) (n int, err error) {
+	log.Printf("%s:%s: xhr back channel send: %s\n", b.sid, b.rid, data)
+
+	n, err = io.WriteString(b.w,
+		strconv.FormatInt(int64(len(data)), 10)+"\n"+string(data))
+
+	b.w.(http.Flusher).Flush()
+
+	if err == nil {
+		b.bytesSent += n
+	}
+
+	return
+}
+
+func (b *xhrBackChannel) discard() {
+	log.Printf("%s:%s: xhr back channel close\n", b.sid, b.rid)
+	close(b.done)
+}
+
+// The chunked HTML back channel implementation used for IE9 and older.
+type htmlBackChannel struct {
+	backChannelBase
+	paddingSent bool
+	domain      string
+}
+
+func (b *htmlBackChannel) send(data []byte) (n int, err error) {
+	log.Printf("%s:%s: html back channel send: %s\n", b.sid, b.rid, data)
+
+	if !b.paddingSent {
+		writeHtmlHead(b.w)
+		writeHtmlDomain(b.w, b.domain)
+	}
+
+	n, err = writeHtmlRpc(b.w, string(data))
+
+	if !b.paddingSent {
+		writeHtmlPadding(b.w)
+		b.paddingSent = true
+	}
+
+	b.w.(http.Flusher).Flush()
+
+	if err == nil {
+		b.bytesSent += n
+	}
+
+	return
+}
+
+func (b *htmlBackChannel) discard() {
+	log.Printf("%s:%s: html back channel close\n", b.sid, b.rid)
+	writeHtmlDone(b.w)
+	close(b.done)
+}
+
+func newBackChannel(sid SessionId, w http.ResponseWriter, html bool,
+	domain string, rid string) (bc backChannel) {
+	base := backChannelBase{sid: sid, rid: rid, w: w, done: make(chan bool)}
+
+	if html {
+		bc = &htmlBackChannel{backChannelBase: base, domain: domain}
+	} else {
+		bc = &xhrBackChannel{base}
+	}
+	return
+}