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