1. Required System DFM Develop Required DFDs from selected BSO
Specify the required solution in more detail with level 2 & 3 DFDs
Support by
Elementary Process Descriptions (narrative descriptions)
I/O Descriptions
External Entity Descriptions
User Roles
Resolve and document Requirement Catalogue changes
Cross check processes against LDS
Logical Data Store/Entity Cross Reference
ensure that the necessary access paths are on the LDS

2. Required System Data Flow Diagrams
Produce full set of DFDs from chosen BSO and Logical DFDs
Amend Logical DFDs to include processing identified in BSO
Exclude any processing now outside the Business System Option boundary
Amend Requirements Catalogue entries as appropriate
eg. A requirement to accept new customers may also involve obtaining a deposit, issuing a receipt and recording the payment.

3. Level 1 DFD Example Yorkies Required Systemh
Driver Instructions
Customer
Booking Clerk b c
Booking Request
Drivers/Agencies
Driver Admin
Receipt/
Confirmation
New drivers/ 1 2
agencies
Driver Required i
Make
Find Drivers
Driver Payroll
Bookings
Deposit d D2
Payments D3
Bookings
Driver Hours and
Marketing/
Agency Days
Pricing D5
Drivers
New Prices 4 D1
Customers 3
List of day's bookings g
Payment a
Record
Depot Clerk
Obtain
Mileages, driver
Customer
New Prices
Departures
Payments
hours, vehicle
and Returns
Invoice/Reminder
Prices D4
Vehicles
Vehicles into/out of Service
Applications
Customer
& changes
acceptance D3
Bookings 5 6
Location Report f e
New Customers
Maintain
Maintain
& changes
relocation
Vehicle Fleet
Sales/Customer
Customer
Vehicle and
Maintenance
Location Info
New And Sold Vehicles
Records
Records D1
Customers
Relocation Bookings

4. Input/Output (I/O) Descriptions
Useful starting point for ongoing design
screens, reports, forms etc
used as basis for I/O structures
From To
Data flow name
Data content
Comments
1.3 a
Booking Confirmation
Customers are sent a
Create
Customer
Booking Confirmation
Confirmed
Booking
Customer No.
Customer Name
The next group of data
items may be repeated
if there are several
bookings being confirmed
at the same time
Booking No.
Vehicle Category Code
Required Booking Start Date
Required Booking
Finish Date
Driver Requirement (Y/N)
Office No. (Start)
Office Name (Start)
Office No. (Finish)
Office Name (Finish) {
only inserted if
one-way hire

5. External Entities
Direct links to the computer system (on-line or off-line)
on-line exteranl entities will map to User Roles
May be inside or outside the organisation
Documented on External Entity Descriptions ID
Name
Description a
Customer
A customer of Yorkieses who hires out or intends to hire out vehicles. b
Drivers/Agencies
Yorkieses employs drivers on a freelance basis for customers'
bookings. If a freelance driver cannot be found a more expensive
agency is contacted who will supply a driver. d
Marketing/Pricing
A department at Yorkieses H.Q. who can modify prices for vehicles
and will receive some reports from the system. h
Booking Clerk
Located in the Local Offices they create bookings for customers
and liaise with the customers. They also liaise with drivers and
agencies, to find those available for customer bookings. g
Depot Clerk
Located in the depots they enter in mileage and other journey
details on completion of bookings.

6. User Catalogue and User Roles
Identify how users interact on-line with the system
used in Dialogue Design
Closely relate to the external entities defined for the required system
User Catalogue defines current jobs
User Catalogue
Job title
Job activities description
Depot Clerk
Select vehicle from required category for customer on
collection. Record mileage, condition, etc. on departure
and return of vehicles.
Driver administrator
Find suitable drivers from Driver/Agency Register. Determine
(Local office)
availability. Find agency if no Yorkieses driver available. Record
driver details on Booking Sheet.

7. User Roles User Roles from User Catalogue
One user role combines job titles where similar activities are performed
in most cases user role to job title will be one-to-one
Different user roles have different access privileges
e.g. Driver Admin is a separate user role from Booking Clerk because only Driver Admin can enter new drivers onto the system

8. User Roles (continued)
Job title
Activities
Depot Clerk
Depot Clerk
Record vehicles departing & returning
Sales/Customer
Salesman
Set up new customers.
Records
Customer records
Amend customer details
clerk
Booking Clerk
Booking clerk
Take bookings from customer
Driver administrator
Find suitable driver for booking
Driver admin
Driver administrator
Select new drivers and agencies from
applicants

9. Define Required System Processing Summary
Specify the required system in terms of its inputs, outputs, and processing.
Perform step in parallel with development of the Required System LDM
Cross-check defined processing against Required System LDM
Expand the chosen Business System Option into a full set of Required DFDs with supporting documentation.
Amend the Requirements Catalogue to include solutions devised in this step.
Develop an I/O Description to define the data content of every required system input and output
Identify User Roles from User Catalogue for subsequent use in Dialogue Design.

10. Develop Required Data Model
Identify changes needed to LDM
Use BSO and Requirements Catalogue
Ensure all attributes have been defined for each entity
Define access, archive, and security requirements for entities and attributes
Check processing defined by the Data Flow Model

11. Incorporating New Requirements Yorkies Example
i. Administer one-way hires and the tracing of vehicles
two relationships between Booking and Local Office: one indicating the from office and the other indicating the to office
ii. Fortnightly invoicing of customers
separation of Booking and Invoice so that one invoice can include several bookings in the fortnight

12. Required System LDS Yorkies Example
Vehicle
Category
Local
required for
classifier of
Office
/Depot
Customer
base of
maker of
employer of
classified by
start
based at
end of
employed by
sender of
Vehicle
Driver
sent by
drive for
used for
Payment
requiring
made by
Agency
from
driven by
split into
Invoice
user of to
drive for
for on
Booking
driven by
paid for by
part of
made to
Allocated
Payment

13. Changes to Supporting Documentation
New Entity Descriptions
New Relationship Descriptions
New attributes on Entity Descriptions
Update Requirements Catalogue
show how requirements are met
Update Logical Data Store/Entity Cross Reference
Extend Entity Descriptions
include non-functional requirements such as access, security and archival