Hot to implement a Scheduler following the requirements...

Hi, may someone help me to solve thies problem?
Problem Description:
An organization, (say a Scool) has some ClassRoom, each classroom may
eat at different time.
Students can order their lunch, they are free to choose the supplier
they prefer from those registered into the application,
even they could order Drinks from Supplier "A" and Pizza from
Supplier "B".
Food Supplier receive the order via e-amail or Fax, to delivery rigth
on time each Supplier needs some minutes of warning.
When a ClassRoom is registered have to set the lunch time, when the
Supplier is registered the warning time has to be set.
The application has to send an order each classroom and each Supplier
in respect of warning time

Example:
- ClassRoom A lunchTime 13:00
- ClassRoom B lunchTime 13:30

- Supplier I warningTime 20 (minutes)
- Supplier II warningTime 40 (minutes) (he is far from the scool)

Example Events:
Time Event
12:20 Order for ClassRoomA sent to Supplier II
12:40 Order for ClassRoomA sent to Supplier I
12:50 Order for ClassRoomA sent to Supplier II
12:10 Order for ClassRoomA sent to Supplier I

Objects and Use Cases:
- There are some ClassRooms
- There are some Food Suppliers.
- Each Classroom has a time to have lunch (lunchTime);
- Each Food Supplier has its own Warning time, that is minutes in
advance he has to be adviced to provide food at that time
(warningTime)
- Untill changes ClassRoom will have lunch every day at same time
- Unitll changes Food Supplier will have ever same warningTime
- Food Supplier may be added/removed and may modify its warningTime
- ClassRoom may be added/removed and may modify its lunchTime



Write correct OO scheduler in order that:
- For every ClassRoom each Food Supplier considering its warningTime
launch a task (at the moment say print Supplier-ClassRoom-Time)
or from another prospective
- For every Supplier n minutes (where n is warningTime) before each
ClassRoom lunchTime launch a task (at the moment say print Supplier-
ClassRoom-Time)

Regards

.