Transactions

ACID Atomic, Consistent, Isolatable, Durable

• Atomic - change whole or nothing (rolled back)
• Consistent - get the right result when you make a request
• Isolated - independent from other transactions
• Durable - survive power/system failure

1. Declaritive
2. Progamatic

Declaritive types

Required

Container must have a transaction

• start new transaction if none exist
• continue transaction if exists

Requires New

Container must always start a new transaction

• existing transaction must be suspended and a new transaction started
  • new transaction independent of first/existing transaction

Not supported

• existing transaction suspended before calling method

Supports

• Transactions may continue but a new transaction is not started if none exists

Mandatory

• Transaction must always exist
• if none exists then TransactionRequiredException thrown

Never

• Transactions not allowed
• RemoteException thrown if client has a transaction