9-1 Chapter 9 (part I): Analysis Classes (Adapted) Object-Oriented Systems Analysis and Design Joey F. George, Dinesh Batra, Joseph S. Valacich, Jeffrey A. Hoffer

9-2 Outline System Logic Activity Diagram Decision Tables Business Rules

9-3 System Logic Aspect of system’s behavior showing flow of control among processes (activities). Depicted in Activity Diagram, Decision Tables, etc. Different types of logic.

9-4 Activity Diagram A diagram that emphasizes the flow of control over processes or object activities by using decision points and other flowchart symbols. Similar to the traditional program flowchart

9-5 Elements of Activity Diagrams Activity – a behavior that an object carries out while in a particular state; an oval shape. Transition, Flow of control – a movement from one activity or state to another; an arrow shape. Decision point – condition(s) that shift control to different paths of activities; a diamond shape. Merge point – point that merges different paths after decision point; a diamond shape. Synchronization bar – bars denoting parallel paths of activities

9-6 Activity diagram with a decision point One of the two possible paths will be selected for each execution of Online Store Sales System

9-7 Activity diagram with synchronization bars Top synchronization bar is a fork. Bottom synchronization bar is a join. in a Sales Management System

9-8 1)Sequential logic – processes run one after another Types of Logic Create Order Check Order Status Place Order Process Invoice to Order Activity Diagram for Purchasing Management System 2) Parallel logic – processes run at the same time (Fig. 9.12); uses synchronizations bars.

9-9 3) Conditional logic – process runs if certain conditions met. Also called IF-THEN logic. - Example: See Fig Example of counter-based decision point: Courses <= 5 Register Student Print “Limit Reached” Yes No Decision point in Course Registration System allowing 5 courses/semester

9-10 Create Special Order 4) Case logic – expanded version of IF-THEN logic. Product in Inventory ? Create Standing Order Create New Order Never procured At min. level At zero level Enter Create Order Module Resembles decision tree. Used also for logic of user interface. Activity Diagram of Create Order Process in Purchasing Management System Merge point Conditions

9-11 5) Loop logic – circular flow (repetition, iteration); variant of IF-THEN logic. Two forms: (a) test a condition, then run a process (while a condition is true, do process) (b) run a process, then test a condition (do process, until a condition is false) Hungry ? Eat Y N Hungry ? Y N Used in lower level diagrams; communicates well to programmers. Activity diagrams may use other symbols for repetition. Also, see Fig Or: 1.Get Login Data 2.Decision: Data Correct? 3.If No at 2, go to 1

9-12 Decision Tables Legend: S=Salaried Employee, K=Hourly Employee; X means that a particular action is chosen.

9-13 Legend: S=Salaried Employee, K=Hourly Employee; X means that a particular action is chosen.

9-14 Business Rules A directive that is intended to influence or guide business behavior. In information systems, business rules are implemented as inferences (decisions), constraints, and program code.

9-15 Types of Business Rules Inferences – Decision points (in activity diagrams; in decision tables that result in attribute values and actions being set). Constraints – Restrictions, mainly in the form of multiplicities (data modeling, implemented as metadata statements), permissible data (type, range), and validation rules (in user interface). Program Code – Calculations and small programs (triggers) that produce some value. This lecture DBMS DBMS; much used in the past