Problem

I ran into an issue with setting up the protobufs for batch txs. Transaction in transaction.proto contains TransactionBody in transaction_body.proto (in the deprecated body field). We want TransactionBody to contain AtomicBatchTransactionBody which contains Transaction. This sets up a circular reference and makes the protobuf compiler mad.

Solution

Option 1: Delete the deprecated body field from Transaction. I started down this path as part of PR #17333. Practically all of the places it was referenced were in tests, so it was a bit of work but not completely unreasonable. I think that if we’re going to delete the deprecated body field we should also delete the other deprecated fields in the Transaction message. However, I’m a bit leery of changing protobufs like this. Are there ancient transactions which depend on it? Is there a reason why these fields were marked deprecated instead of removed altogether? Update: this option will not work per this PR and discussion with the team

Option 2: Combine transation.proto, transaction_body.proto and atomic_batch.proto into a single proto file. This feels messy but should solve the circular dependency

Option 3: We could have a custom transaction.proto(called atomic_transaction.proto or something) with only bytes signedTransactionBytes field in it. And then AtomicBatchTransactionBody would refer to that instead of Transaction

Option 4: AtomicBatchTransactionBody should contain bytes instead of a Transaction.
Instead of this:

message AtomicBatchTransactionBody {
    repeated Transaction transactions = 1;
}

We’d have this:

message AtomicBatchTransactionBody {
    repeated bytes signedTransactionBytes = 1;
}