Evolution of Requirements

1
Evolution of Requirements

• Alistair Sutcliffe
• School of Informatics
• University of Manchester,
• Manchester,
• UK
• ags_at_man.ac.uk
• Design Requirements Workshop- Case Western June
  07

2
Evolution of Requirements

• Application domains are diversifying- games,
  entertainment, web, social computing
• The way we build applications is changing-
  component based SE, ERPs, design by reuse.
• But many problems are fundamentally the same- we
  need to leverage reuse
• Design patterns (GOF to Alexander), so why not
  requirements patterns ?

3
Separating concerns

• Many problems (and hence requirements) do not
  change
• - Jacksons entity model/ functions distinction,
  problem frames
• - Product lines, application frameworks,
  variation points
• Need to identify where evolution is likely to
  occur
• Develop architectures that are reusable but also
  adaptable
• Solution- generalised abstractions of
  requirements problems- see services engineering,
  WSDL, etc.

4
Generalised requirements models
Example- Monitors
Monitor
Domain
Domain Model
a
3
b
properties
detect convert
4
contains
4
2
c
Object
Interpret
Sensor
uses knowledge from
e
d
a
1
5
register signal
change
evaluate

• Generic Requirements
• (a) Noise filters
• (b) Pattern classifiers
• (c) Domain model
• (d) Default assumptions
• (e) Interference interpreters
• (f) Probabilistic interpreters

• Requirements concerns
• 1. Detectability of events
• 2. Fidelity of detection
• 3. Active or passive sensing
• 4. Identifying events
• 5. Accurate Interpretation

5
Implications for RE and Design

• We need to be thinking of Meta-requirements
• - requirements for how systems adapt and change
• - requirements for generic reusable components
• Requirements, design and reuse will converge
• - requirements co-design will be adapting/
  customising composing generic framework and
  components
• Requirements and design will need a
  standardisation process for generic reuse- see
  ERPs, Web Service
• Research Challenge models levels of abstraction
  and variation

6
Thanks and a quick plug for
Understanding Requirements in the Global
Economy Pankaj Jalote- General Chair Alistair
Sutcliffe- Program Chair www.re07.org