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Grokking System Design: Google Docs

Hi - Question is: Why is pub sub being invoked (for any notifications etc.) via API gateway ? When user adds a comment in the session (i.e. in web session), then shouldnt it get generated here itself, rather than via API gateway ?

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Hi Neeraj,

Even though the comment could be generated in the web session itself, using the API gateway to invoke the pub-sub model provides these benefits:

  • Decoupling: The pub-sub model separates comment producers (users adding comments) from consumers (users viewing the document). This flexibility enhances scalability.

  • Scalability: As user numbers grow, the system can handle increased load by adding resources.

  • Real-time Updates: Subscribers receive immediate notifications when a comment is added, enabling real-time viewing

  • Asynchronous Processing : Comments are published to a topic asynchronously, allowing the system to continue processing other tasks. Subscribers receive comments when ready, avoiding system blockage.

Thank you.