Modelling Business Systems 7

1. Modelling Business Systems 7 Systems Methods CB1004 Modelling Business Systems 7

2. Systems Life Cycle – Waterfall Model CB1004 Modelling Business Systems 7

3. Role of soft systems analysis • Why is it relevant? • Looking at the management system and the whole business or organisational system involves sorting human and policy issues • What is the relationship between soft systems and information systems development methods? • At the start of a system, we don’t know what we are developing, hence soft system analysis would be carried out at the beginning CB1004 Modelling Business Systems 7

4. Are methods applied to soft systems different to those applied to hard systems? • Similar concepts e.g. stages, deliverables, iterations, tools and techniques, but with soft systems there are differences due to the nature of the problem • Soft systems concerned with defining the nature of the problem not offering solutions • Hard issues solved by measurement, computation, observation, technical means • Soft issues solved by negotiation, persuasion, compromise CB1004 Modelling Business Systems 7

5. Soft systems method (SSM) • Peter Checkland (1981) • A methodology that brings about improvement in areas of social concern (von Bulow, 1989) • Not an information system development method • The early 7 stage form # (Checkland 1981) evolved into the later form # (Checkland & Scholes, 1990) • Look at the conventional 7 stage model using Mike Harry’s dog registration case# CB1004 Modelling Business Systems 7

6. 1 Situation unstructured • Session 2 given a rich picture of this case# • A rich picture includes all aspects of a situation • Visible &audible • Silent, invisible things e.g. smells • Abstract, emotional things e.g. social atmosphere CB1004 Modelling Business Systems 7

7. 2 Situation analysed • Identifies the themes and issues from the rich picture # • Themes – relate to actual processes • Issues relate to concerns generated in wider activities CB1004 Modelling Business Systems 7

8. 3 Relevant system and root definitions • The qualities we want the system to possess • E.g Identification (relevant system) • An officially enforced system to identify approved owners of dogs (root definition) • How do we know this is a good definition: CATWOE # CB1004 Modelling Business Systems 7

9. CATWOEAn officially enforced system to identify approved owners of dogs • Customers –owners identified? Ambiguous because not explicit who are the recipients or victims of the output • Actors – not clear; needs something to say who will be carrying out the system • Transformation process – clear that the system transforms unidentified dog owners into identified ones; is there an implied ‘approval’ process? CB1004 Modelling Business Systems 7

10. CATWOE An officially enforced system to identify approved owners of dogs • Weltanschauung – ‘officially enforced’ is clear that this system has a strong authoritarian world view • Owner – ‘officially enforced’ implies it is owned by officialdom • Environment – officially enforced’ implies in the context of a legal environment but does not cover the social environment in which it will have to operate CB1004 Modelling Business Systems 7

11. Improved root definition • A legally enforceable agency system to record dog ownership CB1004 Modelling Business Systems 7

12. 4 Conceptual models • Shows the sequence and co-ordination of activities to be carried out to meet the root definition # CB1004 Modelling Business Systems 7

13. 5 Comparison • Can use a matrix# to check each activity in the conceptual model to see if it exists in the real-world • Results then focus on what should be done about it • Absence of activity – a clear indication we need to make it happen? • Trying to find out if it exist may reveal we don’t yet know CB1004 Modelling Business Systems 7

14. 6 Debate • Agenda generated from comparison • Will lead to action for change CB1004 Modelling Business Systems 7

15. 7 Implementation • Implementing change CB1004 Modelling Business Systems 7

16. Developed SSM (DSSM) • Two analysis stream • Logic based • Sequence of task issues, relevant systems, root definitions etc • Cultural analysis • Recognises the process of applying SSM becomes part of the existing situation • Heisenberg’s Uncertainty Principle • Recognises 3 area as a culture • The activity of intervention itself • The ‘social system; in the problem situation • The ‘political system’ in the problem situation CB1004 Modelling Business Systems 7

17. Intervention seen in 3 roles • The client – requested the study • The problem solver • The problem owner • Social system • Mix of human relationships, both formal and informal • Political system • Possession, exchange, clash and resolution dimensions CB1004 Modelling Business Systems 7

18. Process oriented development • Examples include structured analysis methods of Gane and Sarson (1979) and de Marco (1979), couple with structured design methods of Yourdon and Constantine (1978) • Structure – clear stage with deliverable • Top down methods: what the system must be ->what it should do -> how it should be constructed • Transforms raw data (input) into information (output) CB1004 Modelling Business Systems 7

19. SSADM • Structured systems analysis and design method • Selected in 1981 as a mandatory method for UK Government projects • Comprehensive method not requiring a high level of skill to learn but needing guidance from an experienced user CB1004 Modelling Business Systems 7

20. SSADM tools • Data flow diagrams (DFDs) • Data flows, data store and processes used by the system with external entities (sources and destinations for data outside the system) • Logical data structures (LDS) show how data combines to form information • Entity life histories (ELH) shows how information is changed during its lifetime in relation to the entity to which it refers CB1004 Modelling Business Systems 7

21. DFDs • Look at Arbor sales, purchases and operations departments • Identify • External entities to Arbor • Data flows • Context diagram# CB1004 Modelling Business Systems 7

22. DFDs cont • Look at the box Arbor Corporate system • Identify • Departments within Arbor • Data flows between them and the externals • Level 1 DFD # CB1004 Modelling Business Systems 7

23. DFDs cont. • Look at the process ‘Process sales’ (and the notes • Identify • External entities • Processes • Data stores • Data flows • Level 2 DFD # CB1004 Modelling Business Systems 7

24. SSADM • Stages, tools and techniques # • 1 Analysis • Understand the current system and how it works • Identify the problems with the current system • Identify additional requirements for the new system CB1004 Modelling Business Systems 7

25. 2 specification of requirements • Compares the existing physical system against the problems and requirements list • Identifies Business System Options (BSO) – improvements to the system that meet the user requirements • Selection of a BSO leads to a logical view of the required system CB1004 Modelling Business Systems 7

26. 3 Selection of technical options • Identifies technical options and hence limitations e.g. real time or batch processing system CB1004 Modelling Business Systems 7

27. 4 Logical data design5 Logical process design • Usually run in parallel • Defining the way we access data (process) will depend upon how that data is arranged (structure) CB1004 Modelling Business Systems 7

28. 6 Physical design • Turns the logical view of the system into a physical implementation • Dependent on system software used CB1004 Modelling Business Systems 7