1. www.monash.edu.au Analysis and Systems analysis Modelling and IS development Design and Systems design IMS9300 IS/IM FUNDAMENTALS

2. www.sims.monash.edu.au/subjects/ims1501 2 analysis systems analysis in IS development: –take to pieces, separate, distinguish, with a view to ascertaining the elements of anything complex –examine minutely to determine the essential parts (as opposed to accidental or environmental parts) –to discover things about something by a process of analysis

3. www.sims.monash.edu.au/subjects/ims1501 3 complexity of Information Systems even small information systems can be very complex: l many components (lots of information) l much interaction between components l systems within systems l the intangibility of information (hard to define) l the subjective nature of information (variability)

4. www.sims.monash.edu.au/subjects/ims1501 4 abstraction abstraction as an analytical tool: –separating things (in thought) –considering things independently of their attributes –considering attributes independently of the things they are a part of –the idea of something (which doesn’t exist by itself)

5. www.sims.monash.edu.au/subjects/ims1501 5 modelling modelling as an analytical tool: –constructing representations of things –represent the structure of something –represent something natural or artificial showing the proportions and arrangement of its component parts eg. Melways map, Vodaphone Arena scale model, architect’s blueprint

6. www.sims.monash.edu.au/subjects/ims1501 6 Modelling Why do we do it? –Communication with ourselves –Communication with others How do we do it? –informal techniques –formal techniques How effective is it? –different techniques for different purposes –eg. a road map, an organisation chart, a data flow diagram

7. www.sims.monash.edu.au/subjects/ims1501 7 Simplification in modelling all models are simplifications of the real world: they omit some features and emphasise others this is called “abstraction” the choice of model and modelling method requires decisions about: –what things should be included –what things can be omitted

8. www.sims.monash.edu.au/subjects/ims1501 8 Representation in modelling a model is a simulation: it is made from something which represents reality the choice of model and modelling method requires decisions about the form of representation that can best represent the desired aspect of the real-life object being modelled

9. www.sims.monash.edu.au/subjects/ims1501 9 Partitioning in modelling all models simplify complex reality by breaking it down into smaller, less complex parts these can be considered separately this is called “partitioning” the choice of model and modelling method requires decisions about how to partition without losing the overall picture of the thing being modelled

10. www.sims.monash.edu.au/subjects/ims1501 10 Level of detail in modelling partitioning allows the modeller to vary the amount of detail which is given at different levels of the model the choice of model and modelling method requires decisions about how much detail can be included at each level of the model

11. www.sims.monash.edu.au/subjects/ims1501 11 Audience the suitability of different forms and languages for modelling will vary for different audiences all models assume some level of familiarity and understanding on the part of the audience the choice of model and modelling method requires decisions about which modelling form and language the target audience will best understand

12. www.sims.monash.edu.au/subjects/ims1501 12 Purpose of models all models are built to serve some purpose there is no ‘best’ model independent of any purpose the quality of a model is dependent on the purpose for which it was built the choice of model and modelling method requires an understanding of the model’s purpose and decisions about the best method for achieving that purpose

13. www.sims.monash.edu.au/subjects/ims1501 13 Models in analysis and design in order to model a system, the systems analyst must choose an appropriate modelling form in terms of its: –audience –purpose –degree of abstraction (simplification) –form of representation –level of partitioning –level of detail

14. www.sims.monash.edu.au/subjects/ims1501 14 Modelling: for whom? System users and sponsors –e.g compare with someone who wants a house built for them Other systems analysts –e.g. compare with an architect planning a housing estate Designers –e.g. compare with an architect planning the layout and design of rooms in a house Other technical staff - programmers, database builders, systems administrators, etc –e.g. compare with the plumbers, electricians, bricklayers, etc working on a house

15. www.sims.monash.edu.au/subjects/ims1501 15 Modelling information systems Three aspects of information systems are typically modelled: data –e.g. entity relationship diagrams, data structure diagrams process –e.g. function decomposition, structure charts, data flow diagrams behaviour –e.g. entity life history diagrams, state transition diagrams

16. www.sims.monash.edu.au/subjects/ims1501 16 Structured Design breaks complex systems down by partitioning the system into modules, then organising the modules into hierarchies suitable for computer implementation offers a set of strategies for developing a design solution from a well-defined statement of the problem offers a set of criteria for evaluating the quality of a given solution

17. www.sims.monash.edu.au/subjects/ims1501 17 structured design using the data process and data structure models, the target system needs to be factored into design units which: –are easy to build –are easy to test and prove –are easy to maintain –document as a natural by-product –isolate the effect of a given problem –apply principles of re-use –facilitate a large degree of partitioning

18. www.sims.monash.edu.au/subjects/ims1501 18 Structure Charts A system is easier to write and test if we divide it into MODULES MODULE: A named, bounded, set of statements to do a single task, having an identifier by which it can be referenced as a unit. GET VALID TRANSACTION Each of these modules is coded separately

19. www.sims.monash.edu.au/subjects/ims1501 19 Design Features Design features that lead to systems that are easier to maintain and modify: –Small module size.. easier to write and test, and they are less likely to affected by change –Modular independence (coupling).. the less the inside of one module depends upon another, the easier it will be to test and maintain –Modular strength (cohesion).. measures the strength of association of elements within a module

20. www.sims.monash.edu.au/subjects/ims1501 20 Designing information processes processes are the “action” part of businesses capture, manipulate, store and distribute data/ information input: data/information process: manipulate/ combine/ enrich/ separate data/ information (often carried out by people applying their knowledge) output: data/information

21. www.sims.monash.edu.au/subjects/ims1501 21 Designing information processes analyse current information processes. physical model – what happens in real life, who does what, what are the names/types of object involved logical models – the “idea” of what is happening, without reference to how it is implemented build a new logical model – streamline, combine processes, cut redundancies

22. www.sims.monash.edu.au/subjects/ims1501 22 1 edit sales order Sales orders 2 create purchase order sales order Customers Suppliers Purchase Orders Example process purchase orders

23. www.sims.monash.edu.au/subjects/ims1501 23 Process modelling principal techniques –functional decomposition –data flow diagrams associated techniques for modelling the details of low-level processes –structured English –decision tables and decision trees

24. www.sims.monash.edu.au/subjects/ims1501 24 Data Design Database schema: a model of the records and relationships to be implemented by the database Consider: record sizes, record layouts, storage volume requirements, access requirements, data sharing, security, backup requirements An organisation-wide perspective should be adopted to ensure minimum redundancy and inconsistency and to facilitate data sharing

25. www.sims.monash.edu.au/subjects/ims1501 25 Data Modelling Entities – things you require information about eg……………………. Attributes – the properties, qualities or characteristics belonging to those entities you need to have some record of eg…… Relationships between collections of records (entity relationships) – how some classes of things (entities) have a connection in your business activities eg…..

26. www.sims.monash.edu.au/subjects/ims1501 26 Data Modelling Data dictionary – an authoritative description of exactly what data/ information will appear in the system and what form it will take Normalisation – a modification of the data structure to ensure minimal redundancy within the data/information collection, and to ensure flexibity to allow for future change

27. www.sims.monash.edu.au/subjects/ims1501 27 Design on-line interfaces the precise format and layout of all outputs must be specified the data capture method for all inputs must be specified easy-to-learn and easy-to-use interfaces are the aim End-users and managers must be involved: their requirements, opinions and feedback Prototyping is useful

28. www.sims.monash.edu.au/subjects/ims1501 28 Human–Computer Interface Design INTERFACEINTERFACE INTERFACEINTERFACE Programs Database end user direct user The interface is the link between the users and the computer

29. www.sims.monash.edu.au/subjects/ims1501 29 Interface and dialogue design analogous to a conversation between 2 people interface and dialogue design is critical for successful information systems should provide a uniform structure for finding, viewing, and invoking different components of an information system

30. www.sims.monash.edu.au/subjects/ims1501 30 Inputs and outputs: forms and reports form and report design are key ingredients for successful information systems - especially for users forms and reports can be paper-based or screen-based

31. www.sims.monash.edu.au/subjects/ims1501 31 Forms and reports A FORM is a business document containing some predefined data and also some areas for other data to be filled in typically based on one database record A REPORT is a business document that contains only predefined data: a passive document for reading typically contains data from many different database records

32. www.sims.monash.edu.au/subjects/ims1501 32 Inputs and outputs Outputs present information to users: Internal outputs: –Detailed reports, summary reports, exception reports External outputs: –E.g. invoices, statements, turnaround documents Input design involves: –How the data is initially captured, entered and processed –The method and technology used to capture and enter the data –Controls for accuracy of input data

33. www.sims.monash.edu.au/subjects/ims1501 33 Form/report design guidelines Consistency- of operation efficiency- related to user task ease- output self explanatory format- consistent format between entry and display flexibility- must be convenient to user Usability typically refers to: speed- efficient completion of task accuracy- output provides what is expected Satisfaction- output is liked

34. www.sims.monash.edu.au/subjects/ims1501 34 References HOFFER, J.A., GEORGE, J.F. and VALACICH (1999) 2nd ed., Modern Systems Analysis and Design, Benjamin/Cummings, Massachusetts. Chapter 8 Background reading: TURBAN,E., RAINER, R.K. Jnr. and POTTER, R.E. (2003) 2nd ed., Introduction to Information Technology. JOHN WILEY & SONS, INC. Section 2