javax.sip
Interface Transaction

All Superinterfaces:

java.io.Serializable

All Known Subinterfaces:

ClientTransaction, ServerTransaction

public interface Transaction

extends java.io.Serializable

Transactions are a fundamental component of SIP. A transaction is a request sent by a client transaction to a server transaction, along with all responses to that request sent from the server transaction back to the client transactions. User agents contain a transaction layer, as do stateful proxies. Stateless proxies do not contain a transaction layer. This specification provides the capabilities to allow either the SipProvider or SipListener to handle transactional functionality.

This interface represents a generic transaction interface defining the methods common between client and server transactions.

Since:

v1.1

See Also:

TransactionState

Method Summary

java.lang.String	getBranchId() Returns a unique branch identifer that identifies this transaction.
Dialog	getDialog() Gets the dialog object of this transaction object.
Request	getRequest() Returns the request that created this transaction.
int	getRetransmitTimer() Returns the current value of the retransmit timer in milliseconds used to retransmit messages over unreliable transports for this transaction.
TransactionState	getState() Returns the current state of the transaction.
void	setRetransmitTimer(int retransmitTimer) Sets the value of the retransmit timer to the newly supplied timer value.

Method Detail

getDialog

public Dialog getDialog()

Gets the dialog object of this transaction object. A dialog only exists for a transaction when a session is setup between a User Agent Client and a User Agent Server, either by a 1xx Provisional Response for an early dialog or a 200OK Response for a committed dialog.

An implementation must always associate a dialog with a transaction which may result in the creation of a 'dummy' dialog so that the application may always query the dialog from the Transaction. However if a dialog is not yet initialized, the Dialog.getState() must return null to indicate that the dialog has been created but is not yet mapped by the stack to any specific state.

Returns:

the dialog object of this transaction object.

See Also:

Dialog

getState

public TransactionState getState()

Returns the current state of the transaction. The allowable states for client and server transactions are defined in their respective objects.

Returns:

a TransactionState object determining the current state of the transaction.

getRetransmitTimer

public int getRetransmitTimer()
                       throws java.lang.UnsupportedOperationException

Returns the current value of the retransmit timer in milliseconds used to retransmit messages over unreliable transports for this transaction.

Returns:

the integer value of the retransmit timer in milliseconds.

Throws:

java.lang.UnsupportedOperationException - if this method is not supported by the underlying implementation.

setRetransmitTimer

public void setRetransmitTimer(int retransmitTimer)
                        throws java.lang.UnsupportedOperationException

Sets the value of the retransmit timer to the newly supplied timer value. The retransmit timer is expressed in milliseconds and its default value is 500ms. This method allows the application to change the transaction retransmit behavior for different networks. For example the gateway proxy, the internal intranet is likely to be relatively uncongested and the endpoints will be relatively close. The external network is the general Internet. This functionality allows different retransmit times for either side.

Parameters:

retransmitTimer - - the new integer value of the retransmit timer in milliseconds.

Throws:

java.lang.UnsupportedOperationException - if this method is not supported by the underlying implementation.

getBranchId

public java.lang.String getBranchId()

Returns a unique branch identifer that identifies this transaction. The branch identifier is used in the ViaHeader. The uniqueness property of the branch ID parameter to facilitate its use as a transaction ID, was not part of RFC 2543. The branch ID inserted by an element compliant with the RFC3261 specification MUST always begin with the characters "z9hG4bK". These 7 characters are used as a magic cookie, so that servers receiving the request can determine that the branch ID was constructed to be globally unique. The precise format of the branch token is implementation-defined. This method should always return the same branch identifier for the same transaction.

Returns:

the new branch that uniquely identifies this transaction.

getRequest

public Request getRequest()

Returns the request that created this transaction. The transaction state machine needs to keep the Request that resulted in the creation of this transaction while the transaction is still alive. Applications also need to access this information, e.g. a forking proxy server may wish to retrieve the original Invite request to cancel branches of a fork when a final Response has been received by one branch.

Returns:

the Request message that created this transaction.