The document discusses how to work with timers in applications. It describes timers as internal time clocks that perform actions when expired. It provides examples of creating, modifying, and deleting timers using built-in functions. It also discusses using the WHEN-TIMER-EXPIRED trigger to handle timer expirations and giving examples of using timers for periodic queries, displaying messages, and tracking runtime.

1. Working With Timers
http://blog.ebiztechnics.com

2. Objectives
• Describe Timer
• Usage of timer
• Create timer
• Modify timer
• Handle timer expiration
• Delete timer
http://blog.ebiztechnics.com

3. Timers
• What is a timer?
A timer is an "internal time clock" that you programmatically create
to perform an action each time the timer expires.
• Built-ins used:
– FIND_TIMER
– CREATE_TIMER
– SET_TIMER
– DELETE_TIMER
– GET_APPLICATION_PROPERTY
(TIMER_NAME)
http://blog.ebiztechnics.com

4. Usage of Timers
• WHEN-TIMER-EXPIRED Trigger.
• Using timers:
– Periodically query, commit, or rollback
– Show “About…” information at startup
– Display ticker messages
– Display running time
http://blog.ebiztechnics.com

5. Handling Timer Expiration
Start
(R)
T1
When-Timer-Expired (A)
Query
issued
Timer T2
expired T2
Timer T1
expired
(R)
T2,T1
Completed
When-Timer-Expired (T2)
When-Timer-Expired (T1)
Timer T1
created
Timer T2
created
Timer T1
expired
http://blog.ebiztechnics.com

6. Creating a Timer
• Syntax:
• Example:
CREATE_TIMER (timer_name, milliseconds, iterate)
v_timer_id := CREATE_TIMER (‘Time1’, 300,repeat);
http://blog.ebiztechnics.com

7. Modifying a Timer
• Syntax:
• Example:
SET_TIMER (timer_name, milliseconds, iterate)
SET_TIMER (timer_id, milliseconds, iterate)
SET_TIMER (‘Time1’, no_change, no_repeat);
http://blog.ebiztechnics.com

8. Delete Timer
• Syntax:
DELETE_TIMER (timer_name)
DELETE_TIMER (timer_id)
...
IF NOT ID_NULL (FIND_TIMER (‘Time1’)) THEN
DELETE_TIMER (’Time1’);
END IF;
...
http://blog.ebiztechnics.com

9. Find Timer Expiration
• Example:
IF GET_APPLICATION_PROPERTY(TIMER_NAME)=‘Time1’
THEN
Select . . . . .
From t1;
ELSE
:control.time_disp:=:SYSTEM.CURRENT_DATETIME;
END IF;
http://blog.ebiztechnics.com

10. Summary
• Create and modify a timer with built-in
functions
– FIND_TIMER
– CREATE_TIMER
– SET_TIMER
– DELETE_TIMER
– GET_APPLICATION_PROPERTY
(TIMER_NAME)
http://blog.ebiztechnics.com