Technical Session in HDE

1. Implement Server Push
in
Chi-Chia Huang (黃啟嘉)
Oct 24 2014

2. Flask is a microframework for Python based on Werkzeug, Jinja 2

3. Notification from server
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4. client Server
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5. client Server
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6. Server Push Approaches
• Polling
• Long Polling
• Server Sent Events
• Websocket
http://mrjoes.github.io/2013/06/21/python-realtime.html
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7. Time Server/Client
polling, long polling, server sent events, websocket
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8. Polling
Noise to signal ration is usually very high…
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Client

9. Long Polling
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Client

10. Long Polling
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Server
use POST to prevent the browser
from cache the request

11. Server Sent Events
Client
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12. Server Sent Events
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Server
The event stream is a simple stream of text data,
which must be encoded using UTF-8. Each
message is separated by a pair of newline
characters.
https://developer.mozilla.org/en-US/docs/Server-sent_events/Using_server-sent_events#Event_stream_format

13. Event Stream Example
https://developer.mozilla.org/en-US/docs/Server-sent_events/Using_server-sent_events#Event_stream_format
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15. Websocket[RFC6445]
Client
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16. Websocket[RFC6445]
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Server

17. Which one is better?
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• Server-Sent Events
• Are sent over traditional HTTP
• Automatic reconnection
• Ability to send arbitrary events
• WebSockets
• Bi-directional, full-duplex communication

18. Chatroom Example
• Polling approach:
• http://chichia.aws.prd.demodesu.com:5002/type/polling
• Long Polling approach:
• http://chichia.aws.prd.demodesu.com:5002/type/lpolling
• Server Sent Event approach:
• http://chichia.aws.prd.demodesu.com:5002/type/sse
• Websocket approach:
• http://chichia.aws.prd.demodesu.com:5002/type/ws
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19. Intern Training Project
• http://chichia.aws.prd.demodesu.com:8080/
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20. References
• Long Polling
• Jonathan Eunice lpoll
• AlanYang gevent-flask-comet
• Websocket
• Jonathan Eunice flask-ws-example
• Server Sent Event
• Oskar Blom Realtime Server Using The SSE Protocol
• Eric Bidelman Stream Updates with Server-Sent Events
• MDN Using Server Sent Event

21. &
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