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February 16, 2022 14:11
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Small golang / html Server Sent Events (SSE) proof of concept
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| <html> | |
| <head> | |
| <meta charset="UTF-8"> | |
| <title>Server-sent events demo</title> | |
| </head> | |
| <body> | |
| <button>Close the connection</button> | |
| <ul> | |
| </ul> | |
| <script> | |
| var button = document.querySelector('button'); | |
| var evtSource = new EventSource('http://localhost:8000/'); | |
| console.log(evtSource.withCredentials); | |
| console.log(evtSource.readyState); | |
| console.log(evtSource.url); | |
| var eventList = document.querySelector('ul'); | |
| evtSource.onopen = function() { | |
| console.log("Connection to server opened."); | |
| }; | |
| evtSource.onmessage = function(e) { | |
| var newElement = document.createElement("li"); | |
| newElement.textContent = "message: " + e.data; | |
| eventList.appendChild(newElement); | |
| }; | |
| evtSource.onerror = function() { | |
| console.log("EventSource failed."); | |
| }; | |
| button.onclick = function() { | |
| console.log('Connection closed'); | |
| evtSource.close(); | |
| }; | |
| // evtSource.addEventListener("ping", function(e) { | |
| // var newElement = document.createElement("li"); | |
| // | |
| // var obj = JSON.parse(e.data); | |
| // newElement.innerHTML = "ping at " + obj.time; | |
| // eventList.appendChild(newElement); | |
| // }, false); | |
| </script> | |
| </body> | |
| </html> |
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| package main | |
| import ( | |
| "net/http" | |
| "time" | |
| "github.com/rs/cors" | |
| log "github.com/sirupsen/logrus" | |
| "github.com/tmaxmax/go-sse" | |
| ) | |
| func main() { | |
| // Create a server | |
| s := sse.NewServer() | |
| go func() { | |
| // Create our first message | |
| m := sse.Message{} | |
| m.AppendText("Hello world") | |
| // Every second, publish the message | |
| for range time.Tick(time.Second) { | |
| _ = s.Publish(&m) | |
| } | |
| }() | |
| // Setup CORS | |
| uiCorsRouter := cors.New(cors.Options{ | |
| AllowedOrigins: []string{"*"}, | |
| AllowCredentials: true, | |
| }).Handler(s) | |
| // Start the server | |
| if err := http.ListenAndServe(":8000", uiCorsRouter); err != nil { | |
| log.Fatalln(err) | |
| } | |
| } |
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