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System design - Coggle Diagram

- - - - TCP for congested networks and large packets over 512 B or for privacy
  - - - Companies who want HA use low TTL (120 sec)
- - - - AJAX Polling
        
        AJAx sends req at intervals using XMLHttpRequest object, , callback updates web page.
      - With PULL, there''s TTL (30-60sec (up to browser)) so the server doesnt run out of memory from open cnxns
    - - AJAX long polling (BAYEUX protocol)
    - - when we know the response will take longer => persistent connections
        
        heartbeat interceptors to prevent browser killing cnxn from TTL
        
        resource intensive but sometimes needed like a multiplayer game
        
        techniques
        
        AJAX long polling
        
        holds response until there's an update (no empty response)
        
        server sent events
        
        HTML Event source API
        
        real time twitter feed, stock quotes, notifications
        
        Web sockets
        
        bi-directional low latency, open indefnitely
        
        chat, real time social streams, games
        
        HUGE num of reads and writes
        
        not over HTTP, but TCP
        
        initial HTTP asks to upgrade to websocket, if server accepts, happens over TCP
        
        uses the same underlying TCP/IP connection but has its own data framing and handling mechanisms
        
        Streaming over HTTP
        
        stream in chunks with HTML5 and JS STream API
  - - - Statement-based replication
        
        non deterministic like NOW() can be prob
      - Write-ahead log (WAL) shipping
        
        low level byte changes are logged (dependednt on internals)
      - Logical (row-based) log replication
- - - - peer to peer replication with replication factor
      - mutation timestamps