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

SIP Stack 19
SIP Stack Objects
SIP STACK
O
BJECTS
This section describes the main objects that the SIP Stack uses. Figure 2-3
illustrates the ownership relationship between SIP Stack objects.
Figure 2-3 Ownership Relationship Between SIP Stack Objects
STACK OBJECT The SIP Stack object manages all SIP Stack initialization, configuration and
memory management.
DIALOG (CALL-LEG) A SIP call-leg maps to a single SIP call-leg, which is essentially a signaling
relationship between two SIP endpoints. The following fields uniquely identify
SIP call-legs:
 Call-ID
 SIP addresses of both endpoints (To and From headers)
 A special SIP identifier called “tag” attached to the call-leg. To
and From headers
In the SIP Stack, a call-leg object (call-leg) stores states and manages
transactions on behalf of the call-leg.
REGISTER-CLIENT A SIP Registration is a process by which clients notify their current locations to
Registrars that store this information in location servers. In the SIP Stack, a
register-client object (register-client) is responsible for client-side registrations.
Stack Object
Transaction
Subscription
Transaction TransactionTransaction
Register-
Client
Transaction
Transaction
Notify
Dialog
(Call-Leg)
Dialog
(Call-Leg)
Dialog
(Call-Leg)
Transaction