Software Design

Chat App Message Delivery and Read Receipts

UML Sequence Diagrams · made in Skemio

Sequence diagram showing message flow between Sender, Chat Gateway, Database, and Recipient across persistence, delivery ack, and read receipt phases.
Sequence diagram showing message flow between Sender, Chat Gateway, Database, and Recipient across persistence, delivery ack, and read receipt phases.
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What it shows

  • Persistence happens before ack to ensure zero message loss across reloads.
  • Delivery and read receipts travel through independent async feedback loops.
  • Optimistic UI updates prevent client lag while tracking true network state.

The takeaway

Reliable messaging decouples storage acknowledgment from downstream delivery and read receipts.

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