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Distributed systems with distributed, synchronized state is a hard problem. Whatsapp handles 27 billion messages per day. That's almost 50x Twitter's volume. Th
by acchow 13y ago
Distributed systems with distributed, synchronized state is a hard problem. Whatsapp handles 27 billion messages per day. That's almost 50x Twitter's volume. The former behaves like a switch with pretty end-points (the smartphone app), whereas the latter is a massive distributed system storing enormous amounts of state.
If Whatsapp allowed you to log-in from multiple places but didn't synchronize your state for you (i.e., see conversation history that you had on your phone after you've moved to your computer) it would be a pretty unpleasant experience. To accomplish that, the switch-like back end wouldn't be sufficient.
- nightmann 13y agoI'm not sure what Google Talk's traffic is compared to Whatsapp, but gtalk allows simultaneous logins across many devices and does a decent job of synchronizing messages across them -- phone, tablet, computer (though there is a slight delay depending on the volume of messages it needs to sync).
- acchow 13y agoI seriously doubt Google Talk (now called Hangouts) has anywhere close to Whatsapp's traffic. But even if they did, Google can support simultaneous login with synchronized state (and server-stored state) because it's solved a lot of these big problems in the past for other products with hundreds/thousands of engineers.