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Server-side Events with Node.js and Redis
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| redis = require 'redis' | |
| # Make sure multi-line messages are properly formatted | |
| formatData = (data) -> | |
| data.split(/\n/).join "\ndata: " | |
| # Format data as an event | |
| formatEvent = (data) -> | |
| """ | |
| id: #{+new Date} | |
| data: #{formatData data} | |
| """ | |
| # Stream events on redis channel to response | |
| stream = (sub, req, res) -> | |
| res.writeHead 200, | |
| 'content-type': 'text/event-stream' | |
| 'cache-control': 'no-cache' | |
| 'connection': 'keep-alive' | |
| res.write '' | |
| sub.on 'message', (channel, message) -> | |
| res.write formatEvent message | |
| sub.subscribe req.url | |
| req.on 'close', -> | |
| sub.unsubscribe req.url | |
| res.end() | |
| # SSE middleware | |
| module.exports = (sub = redis.createClient()) -> | |
| (req, res, next) -> | |
| if req.accepts 'event-stream' | |
| stream sub, req, res | |
| else | |
| next() |
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| linus@Newton:~$ redis-cli | |
| redis 127.0.0.1:6379> publish /updates.foo "hello there!" | |
| (integer) 1 | |
| redis 127.0.0.1:6379> |
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| http = require 'http' | |
| redis = require 'redis' | |
| # Send data as an event of optional type | |
| sendEvent = (res, data, type) -> | |
| # Make sure multi-line messages are properly formatted | |
| formatData = (data) -> | |
| data.split(/\n/).join "\ndata: " | |
| res.write "id: #{+new Date}\n" | |
| res.write "event: #{type}\n" if type | |
| res.write "data: #{formatData data}\n\n" | |
| # Handle event-stream requests | |
| sendEvents = (req, res) -> | |
| # Write header | |
| res.writeHead 200, | |
| 'content-type': 'text/event-stream' | |
| 'cache-control': 'no-cache' | |
| 'connection': 'keep-alive' | |
| res.write '' # Flush headers | |
| # Subscribe to redis channels matching the request url | |
| sub = redis.createClient() | |
| channels = "#{req.url}.*" | |
| sub.psubscribe channels | |
| # Message handler | |
| sub.on 'pmessage', (pattern, channel, message) -> | |
| # Type is the last part of the channel name | |
| type = channel.split(".").pop() | |
| sendEvent res, message, type | |
| # Clean up when request is closed | |
| req.on 'close', -> | |
| sub.unsubscribe channels | |
| res.end() | |
| # Send the page | |
| sendPage = (req, res) -> | |
| res.writeHead 200, 'content-type': 'text/html' | |
| res.end """<!doctype html> | |
| <html> | |
| <head> | |
| <script> | |
| var logger = function(channel) { | |
| return function(message) { | |
| var data = message.data || message; | |
| console.log(channel + ": ", data); | |
| } | |
| }; | |
| var messages = new EventSource("updates"); | |
| messages.onopen = logger("open"); | |
| messages.onerror = logger("error"); | |
| messages.onmessage = logger("message"); | |
| messages.addEventListener("foo", logger("foo"), false); | |
| messages.addEventListener("bar", logger("bar"), false); | |
| </script> | |
| </head> | |
| <body>hai</body> | |
| </html> | |
| """ | |
| # Create our app | |
| app = http.createServer (req, res) -> | |
| if req.headers.accept is 'text/event-stream' | |
| sendEvents req, res | |
| else | |
| sendPage req, res | |
| app.listen 8000 |
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