A callback is an entry point that needs its own authentication.
LET’S PICTURE IT
A return phone call is not trustworthy merely because it uses a familiar greeting.
SEE IT FOR YOURSELF
A valid counter call, step by stepStep 1 / 4
This example begins with count zero and a request to call increment(). No real contract is deployed.
This example begins with count zero and a request to call increment(). No real contract is deployed.Execution follows the code’s input and permission rules. A website button is not the access-control mechanism.The function reads zero, calculates zero plus one, and writes one to persistent storage.The accepted state contains count one. Later reads can inspect it. Events are emitted only if the code implements them.
Animated local teaching model. No wallet, RPC or live blockchain data. Some labels and hashes are abbreviated for readability.
Identify the expected caller
A pool, router or provider may call a designated callback during a workflow. The receiver must establish that the caller is the intended source.
Bind the active operation
Check the callback belongs to the current action and expected assets or amounts. A valid provider address alone may not bind every supplied parameter.
Protect repeated entry
Callbacks can reenter other functions or occur more than once under some designs. Keep operation state and accounting coherent across those paths.
Test unsolicited calls
Call the callback directly from an unrelated local account and with mismatched operation data. Such calls should not release assets or alter protected accounting.