# Confirmed Transactions

Up until this point, we've explored how to notify LDK of chain activity using blocks. But what if you're sourcing chain activity from a place that doesn't provide a block-centric interface, like Electrum?

LDK has a chain::Confirm interface to support this use case, analogous to the block-oriented chain::Listen interface which we've been using up until now. With this alternative approach, you still need to give LDK block headers but only for blocks containing transactions of interest. These are identified by chain::Filter as before. You also need to notify LDK of any transactions with insufficient confirmation that have been reorganized out of the chain. Use the transactions_confirmed and transaction_unconfirmed methods, respectively.

Additionally, you must notify LDK whenever a new chain tip is available using the best_block_updated method. See the documentation for a full picture of how this interface is intended to be used.


Be advised that chain::Confirm is a less mature interface than chain::Listen. As such, there is not yet a utility like lightning-block-sync to use for interacting with clients like Electrum.