Modern Systems Analysis and Design Fourth Edition Jeffrey

Modern Systems Analysis and Design Fourth Edition Jeffrey A. Hoffer Joey F. George Joseph S. Valacich Appendix 3 Object-Oriented Analysis and Design © 2005 by Prentice Hall

Learning Objectives ü Define events, state transitions, and sequence diagrams. ü Describe concepts and principles of objectorientation. ü Describe activities of the different phases of object-oriented development. ü Compare object-oriented modeling with traditional systems development approaches. ü Develop dynamic models with state, interaction, and activity diagrams. ü Model real-world applications with UML. Appendix 3 -2 © 2005 by Prentice Hall

The Object-Oriented Development Life Cycle Process of progressively developing representation of a system component (or object) through the phases of analysis, design, and implementation The model is abstract in the early stages As the model evolves, it becomes more and more detailed Appendix 3 -3 © 2005 by Prentice Hall

Object oriented cycle is like an onion, evolving from abstract to detailed, from external qualities to system architecture and algorithms. Appendix 3 -4 © 2005 by Prentice Hall

Object-Oriented Deliverables and Outcomes 1. 2. 3. 4. 5. 6. 7. The ability to tackle more challenging problem domains Improved communication among users, analysts, designers, and programmers Increased consistency among analysis, design, and programming activities Explicit representation of commonality among system components Robust systems Reusability of analysis, design, and programming results Increased consistency among the models developed during object-oriented analysis, design, and programming Appendix 3 -5 © 2005 by Prentice Hall

The Unified Modeling Language (UML) A notation that allows the modeler to specify, visualize, and construct the artifacts of software systems, as well as business models Techniques and notations: n n n Appendix 3 -6 Use cases Class diagrams State diagrams Sequence diagrams Activity diagrams © 2005 by Prentice Hall

Use Cases Revisited A depiction of a system’s behavior or functionality under various conditions as the system responds to requests from users Full functioning for a specific business purpose See Chapter 7 Appendix 3 -7 © 2005 by Prentice Hall

Appendix 3 -8 © 2005 by Prentice Hall

Class Diagrams Revisited Features: n n n Objects and classes Encapsulation of attributes and operations Polymorphism Inheritance Aggregation and composition See Chapter 9 Appendix 3 -9 © 2005 by Prentice Hall

Appendix 3 -10 © 2005 by Prentice Hall

Dynamic Modeling Representation of activities that occur throughout the lifetime of a system Types of UML dynamic models n n n State diagram: state changes within an object Sequence diagram: time-sequenced interactions between objects Activity diagram: flow of control between activities within an object Appendix 3 -11 © 2005 by Prentice Hall

State Diagrams State n n A condition during the life of an object during which it satisfies some conditions, performs some actions or waits for some events Shown as a rectangle with rounded corners State Transition n The changes in the attribute of an object or in the links an object has with other objects Shown as a solid arrow Diagrammed with a guard condition and action Event n Something that takes place at a certain point in time, triggering a state transition Appendix 3 -12 © 2005 by Prentice Hall

Guard condition Action Guard condition A transition is labeled with a guard condition and/or an action, separated with a forward slash / State diagram: a model of the states of a single object and the events that cause the object to change from one state to another Appendix 3 -13 © 2005 by Prentice Hall

Diagramming Substates and Decomposing States A state can be expanded into substates using nested state diagrams, similar to expansion of processes in different levels of DFDs. Appendix 3 -14 © 2005 by Prentice Hall

Diagramming Substates and Decomposing States An event can be expanded into using nested state diagrams, and may involve substates and subtransitions and events. Appendix 3 -15 © 2005 by Prentice Hall

Dynamic Modeling: Sequence Diagrams A depiction of the interaction among objects during certain periods of time Elements of a sequence diagram n n Objects: represented by boxes at top of diagram Lifeline: the time during which an object exists Activation: the time period during which an object performs an operation Messages: means by which objects communicate with each other Appendix 3 -16 © 2005 by Prentice Hall

Types of Messages in Sequence Diagrams Synchronous message n The caller must wait for the receiving object to finish executing the called operation before it can resume execution itself Asynchronous message n The caller can resume execution right after sending the message, without waiting for the receiver to complete Simple message n A message that transfers control from the sender to the recipient without describing the details of the communication 20. 17 Appendix 3 -17 © 2005 by Prentice Hall

object lifeline message time Appendix 3 -18 activation © 2005 by Prentice Hall

Process Modeling: Activity Diagrams Shows the conditional logic for the sequence of system activities needed to accomplish a business process Clearly shows parallel and alternative behaviors Can be used to show the logic of a use case Appendix 3 -19 © 2005 by Prentice Hall

Elements of Activity Diagrams Activity: a behavior that an object carries out while in a particular state Transition: a movement from one activity or state to another Branch: a diamond symbol containing a condition whose results provide transitions to different paths of activities Synchronization bar: horizontal or vertical bars denoting parallel or concurrent paths of activities n n Fork: the beginning of parallel activities Join: the end of parallel activities Swimlanes: columns representing different organizatonal units of the system Appendix 3 -20 © 2005 by Prentice Hall

branch activity synchronization bar swimlane Appendix 3 -21 © 2005 by Prentice Hall

Analysis Versus Design Start with existing set of analysis model Progressively add technical details Design model must be more detailed than analysis model Component Diagram n A diagram that shows the software components or modules and their dependencies Deployment Diagram n A diagram that shows how the software components, process and objects are deployed into the physical architecture of the system Appendix 3 -22 © 2005 by Prentice Hall

Appendix 3 -23 © 2005 by Prentice Hall

Summary In this chapter you learned how to: ü ü ü Define events, state transitions, and sequence diagrams. Describe concepts and principles of objectorientation. Describe activities of the different phases of objectoriented development. Compare object-oriented modeling with traditional systems development approaches. Develop dynamic models with state, interaction, and activity diagrams. Model real-world applications with UML. Appendix 3 -24 © 2005 by Prentice Hall