adding sse client

Author: nauman

sseclient/README.md

@@ -0,0 +1,33 @@
+# Server-sent events (SSE) client in Go
+
+I needed a simple client for the events sent from my Spark Core via the
+[Spark API](http://docs.spark.io/api/), unfortunately it includes extra
+lines like `:ok` that is not part of any event.
+
+[![GoDoc](https://godoc.org/github.com/peterhellberg/sseclient?status.svg)](https://godoc.org/github.com/peterhellberg/sseclient)
+
+Based on the work by [@cryptix](https://github.com/cryptix/goSSEClient)
+
+## LICENSE
+
+```
+Copyright (C) 2014 Peter Hellberg
+
+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.
+```

sseclient/sseclient.go

@@ -0,0 +1,111 @@
+// Copyright (C) 2014 Peter Hellberg
+
+// 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.
+package sseclient
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"os"
+)
+
+// Event represents a Server-Sent Event
+type Event struct {
+	Name string
+	ID   string
+	Data map[string]interface{}
+}
+
+// OpenURL opens a connection to a stream of server sent events
+func OpenURL(url string) (events chan Event, err error) {
+	resp, err := http.Get(url)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.StatusCode != 200 {
+		return nil, fmt.Errorf("got response status code %d\n", resp.StatusCode)
+	}
+
+	events = make(chan Event)
+	var buf bytes.Buffer
+
+	go func() {
+		ev := Event{}
+
+		reader := bufio.NewReader(resp.Body)
+
+		for {
+			line, err := reader.ReadBytes('\n')
+			if err != nil {
+				fmt.Fprintf(os.Stderr, "error during resp.Body read:%s\n", err)
+				close(events)
+			}
+
+			switch {
+			// OK line
+			case bytes.HasPrefix(line, []byte(":ok")):
+				// Do nothing
+
+			// id of event
+			case bytes.HasPrefix(line, []byte("id: ")):
+				ev.ID = string(line[4:])
+			case bytes.HasPrefix(line, []byte("id:")):
+				ev.ID = string(line[3:])
+
+			// name of event
+			case bytes.HasPrefix(line, []byte("event: ")):
+				ev.Name = string(line[7 : len(line)-1])
+			case bytes.HasPrefix(line, []byte("event:")):
+				ev.Name = string(line[6 : len(line)-1])
+
+			// event data
+			case bytes.HasPrefix(line, []byte("data: ")):
+				buf.Write(line[6:])
+			case bytes.HasPrefix(line, []byte("data:")):
+				buf.Write(line[5:])
+
+			// end of event
+			case bytes.Equal(line, []byte("\n")):
+				b := buf.Bytes()
+
+				if bytes.HasPrefix(b, []byte("{")) {
+					var data map[string]interface{}
+					err := json.Unmarshal(b, &data)
+
+					if err == nil {
+						ev.Data = data
+						buf.Reset()
+						events <- ev
+						ev = Event{}
+					}
+				}
+
+			default:
+				fmt.Fprintf(os.Stderr, "Error: len:%d\n%s", len(line), line)
+				close(events)
+			}
+		}
+	}()
+
+	return events, nil
+}