Developing a Circuit Update Mechanism




	NOTE: The active/standby model presented below is only one possible HA model. Other models (using database accesses or audit mechanisms to recover circuit states) could also be used.

The circuit methods let an application running over an active HP OpenCall SS7 stack update an application running over a standby stack, prior to granting permission to proceed with a switchover. Using this mechanism prevents a circuit from being found active by an application running over a standby stack, if it is in the process of being deactivated by the application running over the active stack.

To make use of this mechanism, follow these guidelines when developing the application:

All new states, or changes in circuit states, must be propagated by the HP OpenCall SS7 ISUP library of the application running over the standby stack.
All changes in circuit states must be synchronized with the HP OpenCall SS7 ISUP library of the application running over the standby stack.
If the application fails, a switchover to the HP OpenCall SS7 ISUP library of the application running over the standby stack should be performed.
The failed application instance must update its circuit states.

Propagating States

When a request to set up a call has been successfully received or sent by the application running over the active stack, the application should propagate the state for that particular circuit to the application running over the standby stack.

Figure 14-3 Propagation

Synchronizing States

Any further modifications or resetting of the state for the particular circuit should then be synchronized in the HP OpenCall SS7 ISUP library of the application running over the standby stack, ensuring that the inactive library always contains the correct circuit state information.

Figure 14-4 Synchronization

Activating the Standby Application

If a stack fails, or must be deactivated, application failover may be necessary. After the library has been successfully activated, you must activate the necessary probe objects. Then, the application can continue to successfully operate.

Figure 14-5 Activation

Recovering States

Meanwhile, the failed instance of the application can initiate its recovery or updating mechanism, including the updating of all the circuit states as saved in the active (previously standby) HP OpenCall SS7 ISUP library.

Figure 14-6 Recovery

Developing a Circuit Update Mechanism

Technical documentation

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Propagating States

Synchronizing States

Activating the Standby Application

Recovering States