Use Cases Preparation for Thursday 10/2/14

Process or Workflow Model Concepts Representing task, process, procedure, workflow, actions, decisions Functional decomposition – Given a task, what are its subtasks? – Given a subtask, what are its subtasks? – and so on. Endpoint will be individual steps that can be implemented in the system Task: Apply to Graduate School Subtasks: identify schools, take GREs, write essay, request recommendation letters, … Subtask: take GREs sub-subtasks: find a testing site, register for a test date, study, sleep well, show up… Task subtask sub- subtask

Unified Modeling Language (UML) UML is a set of process and models for system analysis and design. “Unified” because they are the result of merging 3 earlier (and similar) approaches for object-oriented modeling. – Booch, G, Rumbaugh, J. Jacobson, I. (2005) The Unified Modeling Language User Guide, 2 nd ed. Addison-Wesley “Degrees” of UML use (Miles & Hamilton). – sketching alternatives – developing blueprints – designs for program architecture and modules (e.g., for Java) We’ll focus on the sketch and blueprint level. Current version is UML 2.0. Like many models, there are variations in notation, syntax, and good style. The modeling software you use may restrict your options, and some organizations adopt a specific style. Tools and Resources – OMG Unified Modeling Language – Visio templates (shapes software) – IBM Rational Rose 01.ibm.com/software/awdtools/developer/rose/ 01.ibm.com/software/awdtools/developer/rose/

Process/Workflow Model Concepts When designing work models, first represent the happy path, then consider the unhappy path. – The happy path is the sequence of steps (user and system) that results in the desired outcome – The unhappy path is any sequence of steps that doesn’t work; it include (or results in) breakdowns. – You can’t possibly think of all the possible unhappy paths – focus on ones you’ve observed or that are most frequent. These are the ones the system should handle and/or seek to prevent. Using the ATM: getting cash Happy path: Insert ATM card enter PIN at prompt select withdraw cash enter amount remove card receive cash Using the ATM: getting cash Unhappy path: Insert ATM card enter PIN at prompt error: incorrect PIN try again, same error ATM keeps ATM card Using the ATM: getting cash ??? path: Insert ATM card enter PIN at prompt error: incorrect PIN try again select withdraw cash enter amount remove card receive cash