HP-UX C SIP Stack Programmer's Guide (Novembery 2007)

Working with Transactions 99
Transaction API
RvSipTransactionRespondMsg()
Use this function to send a prepared Response message to the remote party.
Proxy implementations will use this function in order to proxy a received
response. The response is sent according to the top most Via header found in the
message.
RvSipTransactionIgnoreOutboundProxy()
Instructs the transaction to ignore its outbound proxy. Use this function when
you are about to send a message whose Request-URI was calculated using a
Route header. In such a case, the transaction should ignore its outbound proxy
and use the message Request-URI.
RvSipTransactionSendToFirstRoute()
Use this function to instruct the transaction to send the message to the first route
header in the Route list, and not to the Request-URI. The message should be
sent to the first route header and not to the Request-URI when the message is
sent to a loose route proxy.
EVENTS The Transaction API supplies several events, in the form of callback functions,
to which your application may listen and react. In order to listen to an event,
your application should pass the event handler pointer to the TransactionMgr.
When an event occurs, the transaction calls the event handler function using the
pointer.
The following main events are supplied with the Transaction API:
RvSipTransactionCreatedEv()
This event notifies the application that a new server transaction has been created
and could not be related to any open call-leg. The newly created transaction
always assumes the IDLE state. You should decide whether you wish to handle
this transaction. If so, your application can exchange handles with the SIP Stack
using this callback. You will then be informed of transaction states using the
RvSipTransactionStateChangedEv() callback function. If you choose not to
handle the transaction, the SIP Stack will handle the transaction using its default
behavior. In most cases, the SIP Stack will reply with 501 to the incoming
request. Requests with To and From tags will be responded to with a 481
response.