1. Summary.ppt1 TDT4250 - Modelling of information systems, Fall 2004 Summary of the course Guttorm Sindre / Hallvard Trætteberg, IDI

2. 2 TDT4250 - Modelling of information systems, Fall 2004 Learning goals Study handbook: Overview of languages, techniques and tools to make analysis models and requirements specifications develop models of high quality Ability to choose language/technique according to context Which demands… Skill in making models, evaluating the quality of models Knowing strengths and weaknesses of various types of modelling languages Knowledge of available tool support Be able to work in systems development projects, with emphasis on early phases

3. 3 TDT4250 - Modelling of information systems, Fall 2004 Topics, lecture sequence Week 1-2: initial classifications of methods / languages Ability to navigate in the chaotic landscape of 500+ modelling methods Week 3-7: requirements techniques Theoretical underpinnings + practical skills as requirements analyst  Elicitation techniques, making models from oral input  Security requirements: important but often neglected Week 8-9: i* Ex. of a language supporting other perspectives than UML / ER / DFD Week 10: model quality (kap 3) Week 3-9: how to model; here how to evaluate the quality of models F.Uke 11-12: language quality And then how to evaluate the quality of modelling languages Ability to select a suitable language for your project / company F.Uke 13-14: UI modelling Another example modelling language Model-driven relationship between requirements and UI-design

4. 4 TDT4250 - Modelling of information systems, Fall 2004 Part 1: Initial classifications Dimensions of development methods (ch 8.1) Weltansschauung (objectivistic, constructivistic, mentalistic) Coverage of process (whole development, or only parts, e.g. RE) Coverage of product (whole, or only parts, e.g. just UI) Coverage of semiotic levels (what quality goals are considered?) Coverage of standard techniques? (e.g., reuse, modelling) Guidelines for participant selection Maturity (e.g., used in industry for a long time, or only academic) What should you have learnt from this? The meaning of the various points (Some) ability to use these criteria for evaluating given methods

5. 5 TDT4250 - Modelling of information systems, Fall 2004 Part 1: Initial classifications 7 perspectivesfor modelling languages (ch 2.2) Strukturally oriented (e.g., ER) Functionally oriented (e.g., DFD, use cases, activity diagrams) Behaviour-oriented (e.g., Petri nets, state diagrams) Rule-oriented (e.g. OCL, goal hierarchies in i*) Object-oriented (e.g., UML class and sequence diagrams) Communication-oriented (e.g., speech-act modelling) Aktør/rolle-oriented (e.g., i* dependency models) What should you have learnt from this? The essentials of the various perspectives Examples of languages in various perspectives Purpose, strengths and weaknesses of different types of languages Ability to compare known languages, or classify new languages (with a given definition) wrt perspectives supported

6. 6 TDT4250 - Modelling of information systems, Fall 2004 Part 2: Requirements engineering Papers (1): Nuseibeh & Easterbrook: outlining central issues Nawrocki et al.: RE vs agile techniques (XP)  conflict or possible to combine? Suggest imporvements to XP  Uses analytical frameworks for best practices in RE  Sawyer&Sommerville + CMM Security requirements (3 papers):  Firesmith: types of security requirements, how to represent them  Only textual representation  Sindre & Opdahl: misuse cases  Liu et al: extending i* to analyse security threats What should you have learnt from this? Central issues in RE (activities involved, challenges) Agile techniques: how are these different from trad. RE; strengths and limitations Knowledge of different types of security requirements Ability to compare the different techniques shown for security requirements (textual requirement lists, misuse cases, i* models) Some ability to make requirements or simple models, or to evaluate models in the learnt languages

7. 7 TDT4250 - Modelling of information systems, Fall 2004 Part 2: Requirements engineering (cont.) Papers (2): Hickey & Davis:  Comparing different elicitation techniques  …by an interview study (RE experts) Lloyd et al.:  Comparing different elicitation techniques  …for distributed RE  …through a student experiment Coughlan & Macredie:  analytical comparison of ”soft” methods with a focus on eliciation What should you have learnt from this? Overview of the major elicitation techniques available Strengths and weaknesses of these, when and how to use them Some knowledge of central pitfalls with the most heavily addressed techniques (interviews, workshops),.e.g. leading questions in interviews Ability to suggest a selection of elicitation techniques for a given situation, or to criticize a suggested selection for a given situation

8. 8 TDT4250 - Modelling of information systems, Fall 2004 Part 3: i* (7 papers in total) Purpose of the language, main concepts Two types of models: Strategic dependency (actors, dependencies, …) Strategic rationale (goal hierarchies) How i* fits into a larger development process Couplings to use cases, use case maps, security, human activity modelling, scenarios, textual requirements What should you have learnt from this? Know what i* can be used for Ability to make and evaluate i* models Ability to use goal hierarchies for evaluating solution alternatives (propagating checks up through the hierarchy) Ability to compare and contrast i* with other (known) modelling languages

9. 9 TDT4250 - Modelling of information systems, Fall 2004 Part 4: Model quality The semiotic quality framework (ch 3) Physical, empirical, syntactic, semantic, pragmatic, and social quality (and perceived semantic quality, knowledge quality) Separation of goals and means Adaptation of the framework to requirements specifications (comparing it to Davis’ list of wanted properties for a specification) What should you have learnt from this? Understanding the structure and diffferent levels of the framework Ability to use the framework to evaluate models

10. 10 TDT4250 - Modelling of information systems, Fall 2004 Part 5: Language quality The difference between analytical and empirical evaluation approaches And how they complement each other (Gemino & Wand) Analytical approaches Semiotic framework (ex.: Krogstie’s evaluation of UML) BWW ontology (ex.: Opdahl’s evaluation of UML) Empirical approaches Experiments (e.g., Sinha & Vessey, comparing ER vs OO) Standard exemplars (Feather et al.) to try out modelling languages in practice What should you have learnt from this? Difference between analytical and empirical approaches, pros and cons of both Essentials of the two shown analytical approaches Essentials of experiment design, some knowledge of pitfalls that must be avoided (”threats to validity”) Shortcomings / pitfalls of standard exemplars Some ideas when and how to use various evaluation approaches

11. 11 TDT4250 - Modelling of information systems, Fall 2004 Part 6: UI modelling

12. 12 TDT4250 - Modelling of information systems, Fall 2004 Possible exam questions (not necessarily complete) Modelling & model quality Make model from case description  i*, UI-modelling Evaluate the quality of models  i*, UI-modelling, misuse cases,  textual requirements specifications  UML, ER, DFD (assumed known from before) Explain the 7 perspectives Explain the semiotic quality framework Requirements, elicitation techniques Discuss pros and cons of different techniques Suggest selection of techniques for a given situation Criticize suggested use of techniques in a given situation Compare and contrast interviews and workshops Discuss techniques for security requirements

13. 13 TDT4250 - Modelling of information systems, Fall 2004 Possible exam Qs (cont.) Language quality Use the semiotic framework to evaluate a given language (cf. Krogstie’s UML paper) BWW: not supposed to be able to use this directly, but understand the main principles: what can be evaluated, and how (cf. Opdahl’s UML paper) Understand difference between analytical and empirical approaches, discuss pros, cons, pitfalls Be able to criticize a given language evaluation, whether analytical or empirical Be able to argue for or against the use of a given language in a given context

14. 14 TDT4250 - Modelling of information systems, Fall 2004 Possible exam Qs, (cont.) More theoretical questions Criticize a given paper Compare and contrast the methods and/or findings of several different papers (essential parts or abstracts may be given) Explain (or even criticize, suggest improvements of), main foundations of the course, such as, e.g.,  Dimensions of methods (ch 8.1)  The 7 perspectives of modelling languages (ch 2)  The semiotic quality framework (model quality, ch 3)  The semiotic quality framework (language quality, 3.11)

15. 15 TDT4250 - Modelling of information systems, Fall 2004 Questioning session? The exam is Saturday 11th Dec, 9-13 Books / papers not allowed Do you want a session for questions nearer the exam? Suggest an appropriate time