Software Development 2D1385 2007

1. Software Development2D1385 2007 Karl Meinke CSC KTH karlm@nada.kth.se

2. 1.1. Goals of the Course • After the course you should be able to: • Perform an object-oriented analysis of an informal text-based software requirements document, identifying ambiguities, omissions and inconsistencies; translate such a document into object-oriented requirements using a Noun/Verb/Relational-Phrase methodology, and construct a data dictionary.

3. 2. You should be able to translate the information contained in a data dictionary into a UML class diagram which accurately models the same information, including aggregation, inheritance and multiplicity . 3. You should be able to draw a UML object diagram which correctly instantiates a class diagram under different data constraints. You should be able to abstract information from one or more object diagrams to derive a class diagram.

4. 4. You should be able to critically analyse a short description of a software engineering project and an IT company's business model, and based on this analysis you should be able to recommend a software lifecycle model that is appropriate to the company and the project . 5. You should be able to critically analyse a short description of a software engineering project, and based on this analysis you should be able to recommend a global software architecture and small scale software patterns that are appropriate to the project.

5. 6. You should be able to design and understand language independent data models, based on XML, that can be used to define data interchange standards between software systems, databases, files and communication protocols. You should understand therelationship between data models based on UML class diagrams and DTD data models, so that you can convert between the two. This understanding must also extend to UML object diagrams and XML data files, so that again you can convert between the two.

6. 7. You should understand and be able to use a variety of advanced Java programming features, including Swing GUI components, exceptions, network programming and concurrency, and be able to apply these to small practical exercises arising from lab work.

7. User Requirements UML + OO requirements analysis Architectures + Patterns + OO design + XML Software Requirements Java exceptions + sockets + threads Architecture Design JUnit Detailed design & coding Testing Course Objectives on a Waterfall Model Project Delivery Time

8. 1.1. Övningar • Designed to help you pass the exam • Include exercises and past exam papers • Myself (classes in english) • Lars Arvestad (classes in swedish)

9. 1.2. Lab Exercises • Labs 1,2 Java API, Graphics, event handling • Lab 3 client-server with sockets • Lab 4 XML, syntax and parsing • Lab 5 build a web browser using Java Swing components • Extra lab 6 (see list) bonus points

10. 1.3. Course Book “Software Design” by Eric Braude, 2004 Chapters: 0-2 Programming Concepts 3: Unified Modeling Language UML 4-5: Software Design Principles 6-9: Design Patterns 10-12: Software Components (Beans .NET) 13-14: Software architecture

11. 1.5. Checklist for Submitting Lab Work • Show your UML –design (lab 2-6) • Which architectures/design patterns have been used? (labs 3-6) • Which engineering/management model has been used? (lab 4-6) • How have you documented your program (comments, javadoc etc.) (labs 5-6)

12. 1.5. Checklist (2) • How have you achieved abstraction, encapsulation and modularity? • Which classes have you reused from earlier labs? (With refactoring?) • Which new classes have you used, and why? • Explain how robustness, and reusability are satisfied

13. 1.5. Checklist (3) • How have you performed functional testing? • Point out the most critical pieces of code. • In retrospect, what would you have done differently if the project had continued? • Demonstrate using a program execution that the functional and design requirements are satisfied • Keep it brief !!!!!!!!!!!!!!!!

14. 2.0. Requirements Capture and Analysis with UML The Unified Modeling Language (version 2.0) • Class/Object diagrams (static) • Sequence diagrams (dynamic) • Activity diagrams (dynamic) • Statecharts (dynamic) Standard developed by OMG adopting earlier ideas (Booch, Rumbaugh, Jacobson)

15. 2.1. Requirements Models Models express requirements, architecture & detailed design. (Video Game examples) Use Case Model: In this situation do the following … e.g. how to engage a foreign character

16. Object / Class Model: with objects of these classes … Object provides a set of services, e.g. engagement class. State Model: by reacting to these events … state/event  reaction e.g. if foreign character shoots while we are friendly … run away

17. 2.2. O-O Analysis & Design with UML 2.0 The basic OOA&D approach (iterative) • State the main use cases • Convert the use cases to sequence diagrams • Select the resulting domain classes • If not finished goto 1.

18. 2.3. UML Use Case Diagrams UML gives us a graphical language to organize all our use case scenarios into one overview: Use Case Diagrams These display organisation of: • actors • use cases • associations, • dependencies

19. UML Dependency Activate 1 • Precondition: app has been activated • Clerk clicks • “check out” • Clerk swipes bar code • … • Postcondition: video • is registered to • customer 1 requires Clerk Check in Check out includes requires 1 Add customer Stocker * UML Comment Add video

20. Actor with role name, use case dependency and multiplicity Clerk Use case with name and dependent actors and multiplicities Activate * 1 – one and only one * - zero or more 1 … * - one or more

21. Precondition: app has been activated • Clerk clicks • “check out” • Clerk swipes bar code • … • Postcondition: video • is registered to • customer Pre and postcondition describing black-box effect of executing a use case on the system Expressed as a comment only

22. A Use case dependency requires B A requires B - B must complete before A starts A equivalent B – identical activities and flow, but user sees them as different A extends B – all activities of B are performed but A adds activities or slightly modifies them. Can use to refactor or simplify use cases

23. 2.4. Use Case Modeling In O-O based IT projects, we can begin the requirements analysis phase with a Use Case Analysis A use case is a common or representative situation where one or more external users and/or systems interact with the system to solve an instance of a common problem

24. Notice the underlined word “common” Software seems to obey the statistical Pareto Law 90% of time is spent executing just 10% of the code Therefore care in designing just this 10% of code is “cheap” and will give a good product 90% of the time (at least in theory!)

25. Note: we want to decouple specific users (e.g. John Smith) From their roles, e.g. student, teacher, systems administrator, etc. A role will be called an actor. A specific proper noun (object) e.g. Karl Meinke, may play several roles: teacher, researcher, sys_admin ... etc.

26. Use case modeling involves three steps that are repeated until we are satisfied. Step 1. Identify, name and define each actor in terms of: • Goals, i.e. what the actor wants to do, • Needs, i.e. what services from the system the actor requires to meet each goal.

27. Step 2. For each system service (identified in Step 1), informally describe the • preconditions and • results of the service, and its, • interaction with the actors in: • a typical case (sunny day scenario). • exceptional and error cases (rainy day scenario) Such a service description is called an informal description of a use case scenario.

28. Step 3. For each informal description which is: • mission critical • unclear, or • ambiguous formalise the interaction of the system and the relevant actors using a sequence diagram

29. Step 4. [If necessary, repeat Steps 1-3] Makes an iterative requirements analysis 1. Actors 3. Sequence Diagrams 2. Use cases

30. 2.5. Example Let us analyze requirements on a Warehouse management system Step 1. We begin by identifying nouns, verbs and relational phrases in a requirements document.

31. Warehouse Management SystemRequirements Document The system will support warehouse management. A warehouse worker loads goods from a truck and logs in and out goods using a database. The goods are delivered by a truck driver between warehouses, and distributed within a warehouse by a forklift truck driver. Each warehouse is managed by a foreman, who is able to move goods between warehouses with or without a customer order. A foreman is also able to check the status of a customer order.

32. The requirements document can be marked upas follows.

33. Warehouse Management SystemMarkup Document The system will support warehouse management. A warehouse workerloadsgoods from a truck and logs in and out goods using a database. The goods are delivered by a truck driver between warehouses, and distributed within a warehouse by a forklift truck driver. Each warehouse is managedby aforeman, who is able to move goods between warehouses with or without a customer order. A foreman is also able to check the status of a customer order.

34. The marked up document information can be represented in a data dictionary as follows:

35. Nouns Foreman: actor, responsible for one warehouse. Warehouse Worker: actor, works in a warehouseloading and unloadinggoods. Good: an item to be stored in a warehouse Warehouse: a place to store many goods Verbs Load: A warehouse worker loads goods onto a truck and logs out goods from warehouse using a database. Relational Phrases Foreman responsible for warehouse: One foreman is responsible for one warehouse. Table 2.5.1

36. Notice how we marked up: • Nouns: e.g. foreman, warehouse, … • Verbs: e.g. loading, unloading … • Relational Phrases: e.g. responsible for, works in, … (prepositions?) (Notice the possible overlap between verbs and relational phrases.) This identification work is the heart of O-O requirements analysis and design, since …

37. 2.5.2. Central O-O Dogma • Common Nouns e.g. warehouse, truck, correspond to classes and attributes • Proper Nouns e.g. Karl, Fido, KTH, correspond to objects • Verbs e.g. unload, correspond to methods • Relational Phrases e.g. responsible for, correspond with system structure

38. We will study data dictionaries more in the exercise classes!! The DD definitions are short, but enough to get Started on Step 2. By iterating again later we can add more details. Step 2 asks to focus on the services which the system (warehouse management software) must provide. We build a list of informal use case scenarios.

39. Not every noun will be an actor … (does a forklift truck have any goals ???) … but every actor will be a noun, so: Actors  Nouns

40. Step 2 requires us to look at each actor in turn (in our case there are 4 actors) and ask: • What does this actor want to do (all verbs)? • What does the actor need from the system to accomplish each activity (each verb)? Let’s look at the 1st actor “foreman” and try to identify the goals.

41. (a) A foreman has to be able to moveitems between warehouses with or without a customer order. This use case scenario is called “manual redistribution between warehouses” (b) A foreman also wants to check how far a customer order has been processed. We call this use case scenario “check status of a customer order”.

42. Let’s try to informally define the 1st use case scenario: “manual redistribution between warehouses”. This could be broken down into 4 steps • Initialisation: when a foreman gives a request to do a redistribution.

43. (2) Planning: when the systemplans how to co-ordinate the various transports, and issuestransport requests (3) Loading: when a truckfetches the items from a source warehouse. (4) Unloading: when a truckdeliversitems to a destination warehouse.

44. Is there anything wrong with this use case? • It is very short! - but we can add detail later! • It doesn’t say what happens if things go wrong. - We need to add exception/error cases. - The more of these we add, the more robust our system will be.

45. 2.6. UML Sequence Diagrams A use case scenario describes a sequence of interactions or messages between a collection of actors and the system in order to carry out some task

46. Often we would like to formally model a use case scenario, to study: • timing aspects (relative or absolute) • communication patterns • system states • exception behavior • alternative paths or behaviors

47. 2.6.1. Elementary Concepts A basic sequence diagram depicts a set of objects or processes each of which has its own timeline. Conventionally, objects go across the diagram horizontally, while time goes down the diagram vertically. Down the timelines, between objects, we show messages.

48. Here is our earlier sequence diagram drawn as an SD/MSC: SD Print timeline message object/process C : Computer P : Print_server D : Device time >lpr file print(file, device) print(file,size) >done (time) done done

49. Notice that: • This basic SD has 3 objects and 6 messages • 1 message comes from the environment: >lpr file (from the keyboard??) • 1 message goes to the environment >done(time) (to the screen??) • The environment is an implicit actor • Each timeline has a terminating block at the bottom, which does not mean that the object dissappears/ gets deleted, life goes on!!

50. 2.6.2. The Time Concept An SD/MSC must show dynamic behavior over time Down each timeline we see a set of events . Each event may either be: • sending of a message (arrow tail) • receiving of a message (arrow head)