A

1

• A Whack-The-Balls session
• Every Friday the manager of Whack-The-Balls
  arranges the playing sessions for the week
  beginning in 4 weeks time. At the same time, the
  records of playing sessions from 4 weeks ago are
  deleted.
• Each session is booked either by a team or a
  member. The booking may subsequently be
  cancelled, in which case it will become available
  for re-booking. When the team or member arrives
  to play on the booked court the session is marked
  as played.
• The EEM for Whack-The-Balls records the following
  events for the session entity
• - Make team booking (M)
• - Make member booking (M)
• - Cancel booking (M)
• - Play session (M)
• - Arrange sessions (C/D)
• PRODUCE AN ELH FOR A WHACK-THE-BALLS SESSION.

2
SESSION
ARRANGE NEW SESSION
MANAGE SESSION
USESESSION
DELETE OLD SESSION
o
o

MARK AS PLAYED
----------
BOOK SESSION
CANCEL
o
o
o
o
MAKE TEAM BOOKING
MAKE MEMBER BOOKING
CANCEL TEAM BOOKING
CANCEL MEMBER BOOKING
3
IO Structure Diagram (I/OSD)
BOOK SESSION
GET BOOKING DATA
ISSUE RESPONSE
o
o
o
o
INDIVIDUAL DATA (input)
TEAM DATA (input)
CONFIRMATION (output)
REJECTION (output)
4
A (disjoint) I/OSD Example
Data of copies
Loan status
5
Event Entity Matrix (EEM)Example
Event
6
EEM Views
Event
7
The ELH View (for entity Reader)
Comm. with reader
8
The ECD View (for event Lend)
9

• Produce an ECD for the event ARRANGE SESSION
  (could be old or new).

10
Session Number
NEW SESSION
OLD SESSION
SET OF EQUIPMENT BOOKING
EQUIPMENT BOOKING

11

• Produce an I/O structure diagram for the
  following Whack-The-Balls enquiry function
  description.
• When a playing court number is entered into the
  system it should return a list of all the
  sessions for which the court has been booked,
  giving details of the member or team that placed
  each booking.
• Assume the following attribute names are
  required
• Court
• Session
• Session start time
• Session end time
• Member
• Member name
• Team
• Team name

12

• LDS for Whack-The-Balls scenario

13

• Produce an EAP for the Whack-The-Balls court
  number enquiry report (from a previous slide),
  using the LDS from the immediately previous slide.

14
Court
SET OFSESSION
COURT
SESSION

o
o
BOOKED BY TEAM
BOOKED BY MEMBER
TEAM
Member
15

• CONSIDER THE FOLLOWING TABLE
• Customer Order
• Customer Order
• Customer
• Customer Name
• Customer Address
• Customer Tel.
• Depot
• Depot Name
• Product
• Product Name
• Product Qty
• Product Price
• ANY COMMENTS?...

16

• 1NF no repeating groups.
• Customer Order
• Customer
• Customer Name
• Customer Address
• Customer Tel.
• Depot
• Depot Name
• Customer Order
• Product
• Product Name
• Product Qty
• Product Price

17

• 2NF 1NF no non-key attributes which are
  dependent on only part of the primary key.
• Customer Order
• Customer
• Customer Name
• Customer Address
• Customer Tel.
• Depot
• Depot Name
• Customer Order
• Product
• Product Qty
• Product
• Product Name
• Product Price

18

• 3NF 2NF no non-key attributes which are
  dependent on other non-key attributes.
• Customer Order Customer Order
• Customer
• Depot
• Customer Customer Details
• Customer Name
• Customer Address
• Customer Tel.
• Depot Depot ID
• Depot Name
• Customer Order Customer Order Line
• Product
• Product Qty
• Product Product Details

19
Another ELH Example (1)

• System 1 description
• The system should manage boats taking part in a
  club tournaments. The system should allow boats
  to be registered and de-registered, as well as
  editing of their details. Furthermore, the system
  should allow the allocation and de-allocation of
  boats to races. Only boats registered in the
  system can participate in races. Registered boats
  can have their details and their race allocations
  edited any number of times.

boat

register boat
de-register boat
o
o
edit boat details
allocate boat to race
20
Another ELH Example (2)

• System 2 description
• The system describes the movement of a lift to
  service a call. On receipt of a call and if the
  lift is idle, the lift will leave the floor at
  which it is located and proceed to next floor
  (either up or down). On arrival at a floor, the
  lift will either stop, if that is where the call
  originated from, or proceed with its movement.
  Once the lift stops at a floor, another call will
  make it leave that floor.

lift

leave initial floor
arrive at floor
leave current floor
o
o
stop at floor
-
21
Interpreting an ELH
student
Student permanence
Student departure
Student registration
1 year after student dep.

o
o
Student actions
Normal departure
Premature departure
o
o
o
Enrol in module
Withdraw from module
Amend student det.
Course completed
Student departs