Copied

lib/httpserver/sse.py

@@ -0,0 +1,54 @@
+# Server-sent event support
+#
+# Usage:
+#
+#   import _thread, time
+#
+#   from httpserver.sse import EventSource
+#
+#   @app.route("GET", "/api/greeting")
+#   def api_greeting(conn, request):
+#       """ Say hello every 5 seconds """
+#
+#       def greeting_task(conn, eventsource):
+#           while True:
+#               time.sleep(5)
+#               try:
+#                   eventsource.send(event="greeting", data="hello")
+#               except Exception:  # catch (a.o.) ECONNRESET when the client has disappeared
+#                   conn.close()
+#                   break  # exit thread
+#
+#       _thread.start_new_thread(greeting_task, (conn, EventSource(conn)))
+#
+# Copyright 2022 (c) Erik de Lange
+# Released under MIT license
+
+from .response import HTTPResponse
+
+
+class EventSource:
+    """ Open and use an event stream connection to the client """
+
+    def __init__(self, conn):
+        """ Set up an event stream connection """
+        self.conn = conn
+
+        HTTPResponse(conn, 200, "EVENT_STREAM", close=False, header={"Cache-Control": "no-cache"}).send_file()
+
+    def send(self, data=":", id=None, event=None, retry=None):
+        """ Send event to client following the event stream format
+
+        :param str data: event data to send to client. mandatory
+        :param int id: optional event id
+        :param str event: optional event type, used for dispatching at client
+        :param int retry: retry interval in milliseconds
+        """
+        writer = self.conn
+        if id is not None:
+            writer.write(f"id: {id}\n")
+        if event is not None:
+            writer.write(f"event: {event}\n")
+        if retry is not None:
+            writer.write(f"retry: {retry}\n")
+        writer.write(f"data: {data}\n\n")