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Transactions

Transactions in NS Applications are implemented by the Logic layer. They are provided by the EJB container on every method call by the Proxy layer.

When a method on the bean is called by another class, the transaction attribute decides what the transaction behaviour will be. This transaction attribute is declared with an annotation:

@TransactionAttribute(REQUIRES_NEW)
public void someMethod() {  }

It can have one of the following values:

  • Required (default): Starts a transaction if none is defined, or, if the method is called as part of a bigger transaction, it will join this transaction.
  • RequiresNew: Starts a new transaction. If the method is called as part of a bigger transaction, that transaction will be suspended until this method has finished.
  • Mandatory: Requires an encompassing transaction. Fails if it is called without a transaction.
  • NotSupported: Does not support a transaction. If called as part of a bigger transaction, that transaction will be suspended while this method is being executed.
  • Supports: Can run as part of a transaction, but it does not start a transaction by itself.
  • Never: Does not support a transaction. Fails if called as part of a bigger transaction.

Transactions for Agents​

When calling a method on a DataElement agent, the transaction starts when the proxy calls the method on the bean. That same transaction is committed when the bean returns a result.