In Using Tendermint we discussed different API endpoints for sending transactions and differences between them.
What we have not yet covered is transactional semantics.
When you send a transaction using one of the available methods, it first goes to the mempool. Currently, it does not provide strong guarantees like “if the transaction were accepted, it would be eventually included in a block (given CheckTx passes).”
For instance a tx could enter the mempool, but before it can be sent to peers the node crashes.
We are planning to provide such guarantees by using a WAL and replaying transactions (See this issue), but it’s non-trivial to do this all efficiently.
The temporary solution is for clients to monitor the node and resubmit transaction(s) and/or send them to more nodes at once, so the probability of all of them crashing at the same time and losing the msg decreases substantially.