CB1004 Modelling Business Systems 71 Modelling Business Systems 7 Systems Methods

CB1004 Modelling Business Systems 72 Systems Life Cycle – Waterfall Model

CB1004 Modelling Business Systems 73 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 74 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 75 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 76 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 77 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 78 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 79 CATWOE An 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 710 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 711 Improved root definition A legally enforceable agency system to record dog ownership

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

CB1004 Modelling Business Systems 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 Debate Agenda generated from comparison Will lead to action for change

CB1004 Modelling Business Systems Implementation Implementing change

CB1004 Modelling Business Systems 716 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 717 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 718 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 719 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 720 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 721 DFDs Look at Arbor sales, purchases and operations departments Identify External entities to Arbor Data flows Context diagram#

CB1004 Modelling Business Systems 722 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 723 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 724 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 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 Selection of technical options Identifies technical options and hence limitations e.g. real time or batch processing system

CB1004 Modelling Business Systems Logical data design 5 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 Physical design Turns the logical view of the system into a physical implementation Dependent on system software used