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

94 HP-UX C SIP Stack Programmer’s Guide
Transaction API
Outbound Message
The outbound message is a handle to a message that the transaction will use for
the next outgoing message. Before calling an API function that causes a
message to be sent, the application can get the outbound message and add
headers and a body.
Response Code
A 3-digit integer status code that indicates the outcome of the attempt to
understand and satisfy a request. A server transaction will supply the response
code when calling the RvSipTransactionResponse() API function. A client
transaction can only access the response code parameter with a Get function and
the parameter is not modifiable.
State
Represents the state of the transaction between the client and the server. You
can only access the state parameter with a Get function and it is not modifiable.
Top Via Branch
The Top Via Branch is part of the transaction key and is used to match
responses to their requests. When sending an outgoing request, the transaction
automatically adds a top Via header including a Via branch to the Request
message according to the rules defined in the protocol. If you set the Top Via
branch parameter before calling the RvSipTransactionRequest() function, the
transaction adds this branch to the request top Via header. This parameter has a
Set function only.
Request URI
Indicates the Request-URI of the initial request of the transaction. You can only
access the Request-URI parameter with a Get function and the parameter is not
modifiable. You supply the Request-URI of client transaction when calling the
RvSipTransactionRequest() API function.
Cancel Transaction/Cancelled Transaction
Associate a Cancel transaction with the transaction it cancels and vice versa.
You can retrieve the handle to the INVITE transaction that is being cancelled
from a CANCEL transaction. You can also retrieve the handle to the CANCEL
transaction that cancels this INVITE from an INVITE transaction.