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By wake up condition:
- Time-based - (System Level and User Level )
- At timestamp
- Each `duration`
- For complex use cases Trigger might register itself again to execute at another timestamp
- Time based Triggers seem to be difficult task for synchronization between peers. The following approach is suggested:
Recommendations to execute them should be added by the leader to the block (even if there are no transactions - leader should generate a block with trigger execution recommendations for them)
They are best effort - Iroha does not guarantee them to be executed at exact time. But it guarantees execution at closest possible time if network is operational.
If a leader does not produce a block with appropriate time based triggers in the defined time period after those trigger's selected timestamps - view change happens - similar to how if leader does not produce block for ordinary transactions
Next leader in this case will need to include the previous time based trigger in a block (when a view change happens it will be given a new time window to do this)
- Block number-basedbased - (System Level and User Level )
- At block
- Each `n_blocks`
- For complex use cases Trigger might register itself again to execute at another height
- Transaction-based (Only System Level)
- Before (transaction execution)
- Only for System Level TriggersBefore each
- Have the ability to check and fail or allow transaction
- Have access to all transaction data
- Example: Transaction metadata validation, prohibiting particular instructions, permissions based on instruction inspection
- After (transaction execution)
- After each
- After transaction that triggered a change in WSV that meets arbitrary condition - this is the most general option
- In both cases they have access to transaction contents and at least read access to WSV
- Have the ability to check and fail or allow transaction - if System Level
- Have access to all transaction data and WSV diff after execution
- Example: Transaction fees, permissions based on changes to WSV
- Before (transaction execution)
- Triggers that are triggered by specific ISI call - ExecuteTrigger(Params) - (System Level and User Level )
- Similar to smart contracts as they are in Ethereum blockchain
- Execute as part of the transaction instructions execution
- For System Level - only admin can call the Trigger or through democracy pallet
- Event-based - (System Level and User Level )
- Triggered by events emitted from other triggers or transaction execution.
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