Using transaction state primitives

EAServer provides transaction state primitives that methods can call to direct the outcome of the current transaction. Each component model provides an interface containing methods for these primitives. Table 2-2 lists the API mappings for each component type.

These methods end a component’s participation in a transaction (both cause the current instance to be deactivated):

completeWork The component finished its work for the current transaction and should be deactivated when the method returns. This is the default behavior for stateless CORBA components; a component that calls no state primitive behaves as if this method were called. If long transactions are disabled for the server, this is the default behavior for all CORBA components.

rollbackWork The component cannot complete its work. Doom the current transaction and deactivate the instance when the method returns.

These methods are used to maintain state after the method returns (they delay deactivation of the component instance):

continueWork Continue this component’s participation in the current transaction after the method returns, and allow the transaction to be committed if the component is deactivated.

In stateful CORBA components with long transactions enabled in the server, this is the default behavior if a method calls no transaction primitive.

disallowCommit Continue this component’s participation in the current transaction after the method returns, but roll back the transaction if the component is deactivated before calling another primitive besides disallowCommit.

These primitives can be used to query the state of the transaction (if any) in which the method is executing:

isInTransaction Query whether the current method is executing in the context of a transaction.

isRollbackOnly Query whether the current transaction is doomed to be rolled back or is still viable.

Table 2-2 describes how the transaction primitives are invoked in Java and PowerBuilder components. For information on the Java methods, see Chapter 1, “Java Classes and Interfaces,” in the EAServer API Reference. For information on the PowerBuilder TransactionServer object, see the Application Techniques manual in the PowerBuilder documentation and the PowerBuilder online help.

**Table 2-2: Java and PowerBuilder transaction primitives**
Transaction primitive	Java InstanceContext method	PowerBuilder TransactionServer function
completeWork	completeWork	SetComplete
rollbackWork	rollbackWork	SetAbort
continueWork	continueWork	EnableCommit
disallowCommit	None. You can achieve the same effect by calling, and then raising an exception if deactivate is called before the next method invocation.	DisableCommit
isInTransaction	inTransaction	IsInTransaction
isRollbackOnly	isRollbackOnly	IsTransactionAborted

C and C++ components call the methods and routines in the following table to invoke transaction primitives. See the EAServer API Reference for documentation of these methods and routines:

**Table 2-3: C and C++ transaction primitives**
Transaction primitive	C/C++ routine
completeWork	JagCompleteWork
rollbackWork	JagRollbackWork
continueWork	JagContinueWork
disallowCommit	JagDisallowCommit
isInTransaction	JagInTransaction
isRollbackOnly	JagIsRollbackOnly

Any participating component can roll back the transaction by calling the rollbackWork primitive; Java components can also cause a rollback by returning an unhandled exception. Only the action of the root component determines when EAServer commits the transaction. The transaction is committed when the root component returns with a state of completeWork and no participating component has set a state of disallowCommit.

You can use the transaction state primitives in any component; the component does not have to be declared transactional. Calling completeWork or rollbackWork from methods causes early deactivation. “Supporting early deactivation in your component” discusses how this feature can improve application performance.