Describe a design of a logging protocol for distributed savepoints.

What will be an ideal response?

The transaction manager, TM, provides a tx_create_savepoint procedure that can be called from the application. TM knows the identity of all resource managers participating in the transaction. It calls those resource managers using the xa interface to request that they each create a local savepoint for the transaction and return the savepoint’s identity. TM then writes a savepoint record to its log and returns a distributed savepoint identifier to the application. TM also provides a tx_rollback procedure that can be called by the application. The application provides a distributed savepoint identifier as an argument to the procedure. The procedure locates the savepoint record in its log and calls each resource manager, requesting it to rollback to the appropriate local