From a3265bf7635412788216fc74acacc4cd24ced69f Mon Sep 17 00:00:00 2001
From: Drew Bednar <drew@androiddrew.com>
Date: Fri, 11 Jul 2025 21:14:15 -0400
Subject: [PATCH] Initial commit

---
 README.md | 24 +++++++++++++++++++++++-
 go.mod    |  3 +++
 main.go   | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 73 insertions(+), 1 deletion(-)
 create mode 100644 go.mod
 create mode 100644 main.go

diff --git a/README.md b/README.md
index 1cae2b6..12d99cd 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,25 @@
 # learning_sse
 
-Learning Server Side Events 
\ No newline at end of file
+Learning Server Side Events. 
+
+The magic is in setting the `Content Type` header to `text/event-stream`, writing the response in the from of `data: %s \n\n`, and flushing the content of the WriteResponse buffer manually. This is necessary because by default Go will implicitly flush the buffer only once the Handler has returned. 
+
+
+```
+func SSEHandler(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "text/event-stream")
+
+	tokens := strings.Split("Hey there Drew. I hope you enjoy The Alters!", " ")
+	for _, token := range tokens {
+		w.Write([]byte(fmt.Sprintf("data: %s \n\n", token)))
+		w.(http.Flusher).Flush()
+		time.Sleep(time.Millisecond * 420)
+	}
+}
+```
+
+Use `go run main.go` and try curling the the sse endpoint. 
+
+```
+curl http://0.0.0.0:8888/sse
+```
\ No newline at end of file
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..4c30946
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module git.runcible.io/androiddrew/learning_sse
+
+go 1.21.0
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..ba524a0
--- /dev/null
+++ b/main.go
@@ -0,0 +1,47 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"os"
+	"strings"
+	"time"
+)
+
+func SSEHandler(w http.ResponseWriter, r *http.Request) {
+	w.Header().Set("Content-Type", "text/event-stream")
+
+	tokens := strings.Split("Hey there Drew. I hope you enjoy The Alters!", " ")
+	for _, token := range tokens {
+		w.Write([]byte(fmt.Sprintf("data: %s \n\n", token)))
+		w.(http.Flusher).Flush()
+		time.Sleep(time.Millisecond * 420)
+	}
+}
+
+func routes() http.Handler {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/sse", SSEHandler)
+	return mux
+}
+
+func run(ctx context.Context, w io.Writer, args []string) error {
+
+	addr := fmt.Sprintf("%s:%d", "0.0.0.0", 8888)
+	srv := &http.Server{
+		Addr:    addr,
+		Handler: routes(),
+	}
+	slog.Info("Listing on: http://0.0.0.0:8888")
+	return srv.ListenAndServe()
+}
+
+func main() {
+	ctx := context.Background()
+	if err := run(ctx, os.Stdout, os.Args); err != nil {
+		slog.Error("an error occurred", "error", err)
+	}
+}