Send Item

Sends an item from user account to another, with the following features:

• either user can abort
• no deadlocks exists, even if one player goes offline
• formally verified, items can never be created nor destroyed

source hsm

Design Sketch

the ordered stages of a successful transfer is is:

• IDLE: both players start in the idle state
• TX: A states they want to send their item to B
• RX: B states they want to receive the item from A
• ACK_RX: A acknowledges B
• ACK_TX: B acknowledges A
• Boom, commit inventory updates

However, we allow either user to rollback the transition before the ACK_TX.

The complete deadlock free with rollback:-

Client examples

Client side code for executing a transaction is in the unit tests