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Understanding Transaction Status

How to use the Steem API to check the status of a transaction for a given trx_id value.

The overarching goal is to stop using condenser_api.broadcast_transaction_synchronous but we still want the benefits.

Why Client-side Computation?

The primary reason to compute the trx_id before broadcast is to track the transaction when quality of service is impacted. If the trx_id is known before condenser_api.broadcast_transaction, but the response times out, we can still track the transaction.

Why After Broadcast?

Assuming quality of service has not been impacted, solely relying on the condenser_api.broadcast_transaction response should not be a problem.

Why In General?

Whichever method we use above to get trx_id, we can track it if anything goes wrong while we wait for it to be included in a block. Then, even after it’s included, we can still track a transaction while we wait for 2/3rds of the witnesses to verify (thus irreversable). We can poll transaction_status_api until we’re satisfied that the trx_id has been included.

Client-side Computation

First, create a transaction, for example:

{
   "ref_block_num":20,
   "ref_block_prefix":2890012981,
   "expiration":"2018-10-15T19:52:09",
   "operations":[
      {
         "type":"transfer_to_vesting_operation",
         "value":{
            "from":"alice",
            "to":"bob",
            "amount":{"amount":"8204", "precision":3, "nai":"@@000000021"}
         }
      }
   ],
   "extensions":[]
}

From this, we create a serialization, call it hex:

1400351942ace9efc45b010305616c69636503626f620c2000000000000003535445454d00000

Next, we convert hex to binary, call it bytes and digest bytes, with sha256, call it digest:

eba610257ad6c60d89f84ce54d3e10b52c18d4cce5547867e2450aeac80d9530

Last, we truncate digest to 20 bytes / 40 hex digits:

eba610257ad6c60d89f84ce54d3e10b52c18d4cc

This is the computed trx_id.

After Broadcast

If your client does not support client-side id computation, you can still get the trx_id from the result of condenser_api.broadcast_transaction.

The combination of condenser_api.broadcast_transaction and transaction_status_api.find_transaction, described below, allows us to avoid using condenser_api.broadcast_transaction_synchronous, which is being deprecated.

Polling

Now that we have trx_id, we can poll transaction_status_api.find_transaction, for example:

curl -s --data '{"jsonrpc":"2.0", "method":"transaction_status_api.find_transaction", "params":{"transaction_id":"eba610257ad6c60d89f84ce54d3e10b52c18d4cc"}, "id":1}' https://api.steemit.com

Which returns:

{"jsonrpc":"2.0","result":{"status":"unknown"},"id":1}

We can provide the expiration:

curl -s --data '{"jsonrpc":"2.0", "method":"transaction_status_api.find_transaction", "params":{"transaction_id":"eba610257ad6c60d89f84ce54d3e10b52c18d4cc","expiration":"2018-10-15T19:52:09"}, "id":1}' https://api.steemit.com

Which returns:

{"jsonrpc":"2.0","result":{"status":"too_old"},"id":1}

Possible status results are:

Status Meaning
unknown Expiration time in future, transaction not included in block or mempool
within_mempool Transaction in mempool
within_reversible_block Transaction has been included in block, block not irreversible (result will also contain block_num)
within_irreversible_block Transaction has been included in block, block is irreversible (result will also contain block_num)
expired_reversible Transaction has expired, transaction is not irreversible (transaction could be in a fork)
expired_irreversible Transaction has expired, transaction is irreversible (transaction cannot be in a fork)
too_old Transaction is too old, I don’t know about it

See: transaction_status_api