If you want to perform data stream validation, you should probably use stream filters which are available in MultiChain 2.0 (now in alpha, but fully functional):
Please note that stream filter validation is not performed by miners, but it is performed by both honest publisher and honest subscribers. So data that violates a stream filter will not be retrieved via the stream querying APIs.
If you need stricter stream data validation than this, you can use transaction filters. But this will only be effective for on-chain stream data, not off-chain data.