Master contract

1. Data Update Event data structure:

• data type hash (256bit) — unique identifier of the data provider
• receiving contract address

2. Method requestData()

• should dispatch a Data Update Event for oracles to process.

Consumer contract

1. Private method check_data_age()

• should check whether the data is up to date or not.
• should throw if data is antique.
• data is considered outdated after a specified timeout in seconds or blocks. Oudated data should be updated immediately (in the same transaction).
• data is considered antique after a specified timeout in seconds or blocks. Antique data prevents contract from processing any more transactions until it's manually updated.
• timeout should be configurable in the contract variable.

2. Private method request_data()

• should request new data from the Master contract.
• should be called automatically when the data is outdated (check_data_age() returns truthy value).

3. Public method request_data_manually()

• can be called only if data is outdated or antique (tested by check_data_age()).
• calls request_data() internally.

4. Restricted method update_data()

• can be called only by Ducatur Oracle.
• updates data in the contract.