1. An interface between a transaction manager and a first transaction participant, comprising: an instruction passing mechanism enabling the transaction manager to specify a first phase of a first transaction for performance by the first transaction participant, and the first transaction participant to specify a second phase of a second transaction for performance by a second transaction participant; and a status passing mechanism enabling the first transaction participant to indicate a first completion status of the first phase of the first transaction, and the second transaction participant to indicate a second completion status of the second phase of the second transaction.