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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,21 @@ | ||
| <!DOCTYPE html> | ||
| <html> | ||
| <body> | ||
|
|
||
| <h1>Getting server-sent updates</h1> | ||
| <div id="result"></div> | ||
|
|
||
| <script> | ||
| // Example taken from: https://www.w3schools.com/html/html5_serversentevents.asp | ||
| if (typeof (EventSource) !== "undefined") { | ||
| const source = new EventSource("/sse?stream=time"); | ||
| source.onmessage = function (event) { | ||
| document.getElementById("result").innerHTML += event.data + "<br>"; | ||
| }; | ||
| } else { | ||
| document.getElementById("result").innerHTML = "Sorry, your browser does not support server-sent events..."; | ||
| } | ||
| </script> | ||
|
|
||
| </body> | ||
| </html> |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,55 @@ | ||
| package main | ||
|
|
||
| import ( | ||
| "errors" | ||
| "github.com/labstack/echo/v4" | ||
| "github.com/labstack/echo/v4/middleware" | ||
| "github.com/r3labs/sse/v2" | ||
| "log" | ||
| "net/http" | ||
| "time" | ||
| ) | ||
|
|
||
| func main() { | ||
| e := echo.New() | ||
|
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| server := sse.New() // create SSE broadcaster server | ||
| server.AutoReplay = false // do not replay messages for each new subscriber that connects | ||
| _ = server.CreateStream("ping") // EventSource in "index.html" connecting to stream named "ping" | ||
|
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| go func(s *sse.Server) { | ||
| ticker := time.NewTicker(1 * time.Second) | ||
| defer ticker.Stop() | ||
|
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||
| for { | ||
| select { | ||
| case <-ticker.C: | ||
| s.Publish("time", &sse.Event{ | ||
| Data: []byte("time: " + time.Now().Format(time.RFC3339Nano)), | ||
| }) | ||
| } | ||
| } | ||
| }(server) | ||
|
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| e.Use(middleware.Logger()) | ||
| e.Use(middleware.Recover()) | ||
| e.File("/", "./index.html") | ||
|
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| //e.GET("/sse", echo.WrapHandler(server)) | ||
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| e.GET("/sse", func(c echo.Context) error { // longer variant with disconnect logic | ||
| log.Printf("The client is connected: %v\n", c.RealIP()) | ||
| go func() { | ||
| <-c.Request().Context().Done() // Received Browser Disconnection | ||
| log.Printf("The client is disconnected: %v\n", c.RealIP()) | ||
| return | ||
| }() | ||
|
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| server.ServeHTTP(c.Response(), c.Request()) | ||
| return nil | ||
| }) | ||
|
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| if err := e.Start(":8080"); err != nil && !errors.Is(err, http.ErrServerClosed) { | ||
| log.Fatal(err) | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,21 @@ | ||
| <!DOCTYPE html> | ||
| <html> | ||
| <body> | ||
|
|
||
| <h1>Getting server-sent updates</h1> | ||
| <div id="result"></div> | ||
|
|
||
| <script> | ||
| // Example taken from: https://www.w3schools.com/html/html5_serversentevents.asp | ||
| if (typeof (EventSource) !== "undefined") { | ||
| const source = new EventSource("/sse"); | ||
| source.onmessage = function (event) { | ||
| document.getElementById("result").innerHTML += event.data + "<br>"; | ||
| }; | ||
| } else { | ||
| document.getElementById("result").innerHTML = "Sorry, your browser does not support server-sent events..."; | ||
| } | ||
| </script> | ||
|
|
||
| </body> | ||
| </html> |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,49 @@ | ||
| package main | ||
|
|
||
| import ( | ||
| "errors" | ||
| "github.com/labstack/echo/v4" | ||
| "github.com/labstack/echo/v4/middleware" | ||
| "log" | ||
| "net/http" | ||
| "time" | ||
| ) | ||
|
|
||
| func main() { | ||
| e := echo.New() | ||
|
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| e.Use(middleware.Logger()) | ||
| e.Use(middleware.Recover()) | ||
| e.File("/", "./index.html") | ||
|
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| e.GET("/sse", func(c echo.Context) error { | ||
| log.Printf("SSE client connected, ip: %v", c.RealIP()) | ||
|
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| w := c.Response() | ||
| w.Header().Set("Content-Type", "text/event-stream") | ||
| w.Header().Set("Cache-Control", "no-cache") | ||
| w.Header().Set("Connection", "keep-alive") | ||
|
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||
| ticker := time.NewTicker(1 * time.Second) | ||
| defer ticker.Stop() | ||
| for { | ||
| select { | ||
| case <-c.Request().Context().Done(): | ||
| log.Printf("SSE client disconnected, ip: %v", c.RealIP()) | ||
| return nil | ||
| case <-ticker.C: | ||
| event := Event{ | ||
| Data: []byte("time: " + time.Now().Format(time.RFC3339Nano)), | ||
| } | ||
| if err := event.MarshalTo(w); err != nil { | ||
| return err | ||
| } | ||
| w.Flush() | ||
| } | ||
| } | ||
| }) | ||
|
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||
| if err := e.Start(":8080"); err != nil && !errors.Is(err, http.ErrServerClosed) { | ||
| log.Fatal(err) | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,75 @@ | ||
| package main | ||
|
|
||
| import ( | ||
| "bytes" | ||
| "fmt" | ||
| "io" | ||
| ) | ||
|
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| // Event represents Server-Sent Event. | ||
| // SSE explanation: https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events#event_stream_format | ||
| type Event struct { | ||
| // ID is used to set the EventSource object's last event ID value. | ||
| ID []byte | ||
| // Data field is for the message. When the EventSource receives multiple consecutive lines | ||
| // that begin with data:, it concatenates them, inserting a newline character between each one. | ||
| // Trailing newlines are removed. | ||
| Data []byte | ||
| // Event is a string identifying the type of event described. If this is specified, an event | ||
| // will be dispatched on the browser to the listener for the specified event name; the website | ||
| // source code should use addEventListener() to listen for named events. The onmessage handler | ||
| // is called if no event name is specified for a message. | ||
| Event []byte | ||
| // Retry is the reconnection time. If the connection to the server is lost, the browser will | ||
| // wait for the specified time before attempting to reconnect. This must be an integer, specifying | ||
| // the reconnection time in milliseconds. If a non-integer value is specified, the field is ignored. | ||
| Retry []byte | ||
| // Comment line can be used to prevent connections from timing out; a server can send a comment | ||
| // periodically to keep the connection alive. | ||
| Comment []byte | ||
| } | ||
|
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| // MarshalTo marshals Event to given Writer | ||
| func (ev *Event) MarshalTo(w io.Writer) error { | ||
| // Marshalling part is taken from: https://github.com/r3labs/sse/blob/c6d5381ee3ca63828b321c16baa008fd6c0b4564/http.go#L16 | ||
| if len(ev.Data) == 0 && len(ev.Comment) == 0 { | ||
| return nil | ||
| } | ||
|
|
||
| if len(ev.Data) > 0 { | ||
| if _, err := fmt.Fprintf(w, "id: %s\n", ev.ID); err != nil { | ||
| return err | ||
| } | ||
|
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| sd := bytes.Split(ev.Data, []byte("\n")) | ||
| for i := range sd { | ||
| if _, err := fmt.Fprintf(w, "data: %s\n", sd[i]); err != nil { | ||
| return err | ||
| } | ||
| } | ||
|
|
||
| if len(ev.Event) > 0 { | ||
| if _, err := fmt.Fprintf(w, "event: %s\n", ev.Event); err != nil { | ||
| return err | ||
| } | ||
| } | ||
|
|
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| if len(ev.Retry) > 0 { | ||
| if _, err := fmt.Fprintf(w, "retry: %s\n", ev.Retry); err != nil { | ||
| return err | ||
| } | ||
| } | ||
| } | ||
|
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| if len(ev.Comment) > 0 { | ||
| if _, err := fmt.Fprintf(w, ": %s\n", ev.Comment); err != nil { | ||
| return err | ||
| } | ||
| } | ||
|
|
||
| if _, err := fmt.Fprint(w, "\n"); err != nil { | ||
| return err | ||
| } | ||
|
|
||
| return nil | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,44 @@ | ||
| --- | ||
| description: SSE recipe | ||
| --- | ||
|
|
||
| # Server-Sent-Events (SSE) | ||
|
|
||
| [Server-sent events]( | ||
| https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events#event_stream_format) can be | ||
| used in different ways. This example here is per connection - per handler SSE. If your requirements need more complex | ||
| broadcasting logic see https://github.com/r3labs/sse library. | ||
|
|
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| ## Using SSE | ||
|
|
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| ### Server | ||
|
|
||
| ```go reference | ||
| https: //github.com/labstack/echox/blob/master/cookbook/sse/simple/server.go | ||
| ``` | ||
|
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| ### Event structure and Marshal method | ||
|
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| ```html reference | ||
| https://github.com/labstack/echox/blob/master/cookbook/sse/simple/serversideevent.go | ||
| ``` | ||
|
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| ### HTML serving SSE | ||
|
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| ```html reference | ||
| https://github.com/labstack/echox/blob/master/cookbook/sse/simple/index.html | ||
| ``` | ||
|
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| ## Using 3rd party library [r3labs/sse](https://github.com/r3labs/sse) to broadcast events | ||
|
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| ### Server | ||
|
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| ```go reference | ||
| https: //github.com/labstack/echox/blob/master/cookbook/sse/broadcast/server.go | ||
| ``` | ||
|
|
||
| ### HTML serving SSE | ||
|
|
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| ```html reference | ||
| https://github.com/labstack/echox/blob/master/cookbook/sse/broadcast/index.html | ||
| ``` |