Scheduled Transaction

Overview

A scheduled transaction is a transaction with the ability to collect the required signatures on a Hedera network in preparation for its execution. Unlike other Hedera transactions, this allows you to queue a transaction for execution in the event you do not have all the required signatures for the network to immediately process the transaction. A scheduled transaction is used to create a scheduled transaction. This feature is ideal for transactions that require multiple signatures.

When a user creates a scheduled transaction, the network creates a scheduled entity. The scheduled entity receives an entity ID just like accounts, tokens, etc called a schedule ID. The schedule ID is used to reference the scheduled transaction that was created. The transaction that is being scheduled is referenced by a scheduled transaction ID. The scheduled transaction can be referred to as the outer transaction while the scheduled transaction can be referenced as the inner transaction.

Signatures are appended to the scheduled transaction by submitting a ScheduleSign transaction. The ScheduleSign transaction requires the schedule ID of the scheduled transaction the signatures will be appended to. In its current design, a scheduled transaction has 30 minutes to collect all required signatures before the scheduled transaction can be executed or will be deleted from the network. You can delete a scheduled transaction by setting an admin key to delete a scheduled transaction before it is executed or deleted by the network.

You can request the current state of a scheduled transaction by querying the network for ScheduleGetInfo. The request will return the following information:

• Schedule ID

• Account ID that created the scheduled transaction

• Account ID that paid for the creation of the scheduled transaction

• Transaction body of the inner transaction

• Transaction ID of the inner transaction

• Current list of signatures

• Admin key (if any)

• Expiration time

• The timestamp of when the transaction was deleted, if true

The design document for this feature can be referenced here.

Schedule Transaction ID

Hedera Transaction IDs are composed of the account ID submitting the transaction and the transaction valid start time in seconds.nanoseconds (0.0.1234@1615422161.673238162). The transaction ID for a scheduled transaction will include "?schedule" at the end of the transaction ID which identifies the transaction as a scheduled transaction i.e. 0.0.1234@1615422161.673238162?scheduled. The transaction ID of the scheduled (inner) transaction inherits the transaction valid start time and account ID from the scheduled (outer) transaction.

Schedule Transaction Receipts

The transaction receipt for a schedule that was created contains the new schedule entity ID and the scheduled transaction ID. The scheduled transaction ID is used to request records for the inner transaction upon successful execution.

Schedule Transaction Records

Transaction records are created when the scheduled transaction is created, for each signature that was appended, when the scheduled transaction is executed, and if the scheduled transaction was deleted by a user. The record of a scheduled transaction includes a schedule reference property which is the ID of the schedule the record is associated with. To get the transaction record for the inner transaction after successful execution, you can do the following:

1. Poll the network for the specified scheduled transaction ID. Once the scheduled transaction executes the scheduled transaction successfully, request the record for the scheduled transaction using the scheduled transaction ID.

2. Query a Hedera mirror node for the scheduled transaction ID.

3. Run your own mirror node and query for the scheduled transaction ID.