Abstract: A process group resource manager for managing protected resources during transaction processing is disclosed. The process group resource manager comprises a first process configured to provide access to a protected resource during one or more transactions, the first process being further configured to construct a transaction record for each respective transaction, wherein each transaction record includes each request message received by the first process and each response message sent by the first process during a particular transaction. The process group resource manager further comprises a second process configured to serially replay the transactions in which the first process participates, the second process being configured to cause a particular transaction to rollback if the replay of that transaction does not match the transaction record constructed by the first process for that transaction.