Functional Models and Use-Case Diagrams

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Questions and Answers

What is the primary purpose of a use-case diagram?

To support logical modeling of business processes

To model the flow of objects in a process

To describe the basic functions of an information system (correct)

To represent execution paths in a workflow

Which nodes in an activity diagram are used to control the flow of activities?

Fork node and Join node

Control Flows and Object Flows

Initial node and Decision node

Control Nodes (correct)

What does an initial node represent in an activity diagram?

The beginning of the set of actions (correct)

A branch point in execution

The end of all activities

A point to merge execution paths

Which statement about activity diagrams is true?

They describe processes in a general and abstract manner Signup and view all the answers

What is the function of a merge node in an activity diagram?

To rejoin multiple paths into a single flow Signup and view all the answers

What is the purpose of performing a walkthrough in the use-case verification process?

To ensure each action in the activity diagram is recorded in the use-case Signup and view all the answers

Which rule is NOT part of the verification and validation process for use-cases?

Multiple descriptions may exist for a single use-case Signup and view all the answers

What is the role of the recorder (scribe) in a use-case review meeting?

To document errors and take notes during discussions Signup and view all the answers

What should be ensured about the sequence of the use-case description?

It must follow the sequential order of the activity diagram Signup and view all the answers

Which statement about the relationships depicted in the use-case description is true?

All relationships must be visually represented on the use-case diagram Signup and view all the answers

What is the primary function of swim lanes in an activity diagram?

To assign responsibility to objects or individuals performing activities Signup and view all the answers

Which of the following is NOT a guideline for creating activity diagrams?

Use freehand drawing for flexibility Signup and view all the answers

What aspect does a use case primarily depict?

The user activities and system responses Signup and view all the answers

Which of the following describes a normal flow in a use case?

The standard sequence of activities performed Signup and view all the answers

What is a characteristic of sub-flows in a use case?

They simplify normal flows by breaking them down Signup and view all the answers

What is represented by the 'Extend' relationship in a use case?

A new use case that adds optional behavior to an existing use case Signup and view all the answers

Which of the following guidelines is important when writing use cases?

Writing in the form of subject-verb-direct object Signup and view all the answers

What should be listed in the overview of a use-case description?

Primary actor and its type Signup and view all the answers

Study Notes

Functional Models

Describe business processes and the interaction of an information system with its environment.
Used in object-oriented system development to describe functionality.
Two types of functional models exist: use-case diagrams and activity diagrams.
The models are logical, independent of how they are implemented (manual or computerized).

Use-Case Diagrams

Describe the basic functions of an information system.
Provide a simple, high-level view of the system's functionality.
Drawn when gathering and defining requirements.
Elements:
- Actors: represent users or external systems.
- Use Cases: represent specific functions or tasks.
- Relationships: connections between actors and use cases (association, extend, include, generalization).

Activity Diagrams

Support the logical modeling of business processes and workflow.
Depict the sequence of activities in a process.
Abstract and describe processes in general terms.
Model behavior independently of objects, applicable to any type of process.
Elements:
- Activity Nodes: represent individual activities.
- Object Nodes: represent the flow of information.
- Control Flows: model execution paths.
- Object Flows: model the flow of objects.
- Control Nodes: 7 types.
- Initial node: the beginning of the set of actions/activities.
- Final-activity node: stops all actions/activities.
- Final-flow node: stops one execution path but allows others to continue.
- Decision node: represents a test to determine which path to use to continue.
- Merge node: rejoins mutually exclusive execution paths.
- Fork node: separates a single execution path into multiple parallel paths.
- Join node: rejoins parallel execution paths.
- Swim lanes: used to assign responsibility to objects or individuals.
- Represent a separation of roles.

Creating Activity Diagrams

Choose a previously identified business process.
Review requirements definition, use-case diagrams, and other documentation.
Identify the activities within the business process.
Identify control flows and nodes.
Identify object flows and nodes.
Lay out the diagram, minimizing crossing lines.

Use Cases

The primary driver for UML diagramming techniques.
Depict activities performed by users.
Describe basic functions of the system:
- What the user can do.
- How the system responds.
Building blocks for continued design activities.
Each use-case describes only one function.

Elements of a Use Case Description

Overview:
- Name.
- ID Number.
- Type (overview or detail; essential or real).
- Primary Actor.
- Brief Description.
- Importance Level.
- Stakeholder(s).
- Trigger(s).
Relationships:
- Association: communication between the use case and actors.
- Extend: extends the functionality of a use case.
- Include: includes another use case.
- Generalization: allows use cases to support inheritance.
Flow of events:
- Normal flow: the usual set of activities.
- Sub-flows: decomposed normal flows for simplicity.
- Alternate or exceptional flows: those not considered the norm.
Optional characteristics: complexity, time, etc.

Use Case Writing Guidelines

Write in subject-verb-direct object format.
Clarify the initiator of each step.
Write from an independent observer's perspective.
Maintain consistent abstraction levels.
Ensure use cases have a sensible set of steps.
Keep use cases simple.
Write repeating instructions after the steps to be repeated.

Creating Use-Case Descriptions

Pick a high-priority use-case and create an overview:
- List the primary actor.
- Determine its type: overview, detail, essential, real.
- List stakeholders and their interests.
- Determine the importance level.
- Briefly describe the use-case.
- List what triggers the use-case.
- List its relationship to other use-cases.
Fill in the steps of the normal flow of events to complete the use-case.
Ensure steps are not too complicated or long, maintain consistent size with other steps.
Identify and write alternate or exceptional flows.
Review the description for correctness.
Iterate over all steps again.

Verification & Validation of Use Cases

Performed by the development team and client.
Involves a walkthrough of the models and diagrams.
Facilitator schedules and sets up the meeting.
Presenter is responsible for the representation being reviewed.
Recorder takes notes and documents errors.

Rules for Verification & Validation

Ensure one recorded event in the flow of events for each action/activity on the activity diagram.
All objects in an activity diagram should be mentioned in a use-case event.
The sequence of events in the use-case description should match the sequence in the activity diagram.
One and only one description for each use-case.
All actors in a use-case description should be shown on the use-case diagram.
Stakeholders in the use-case description may be shown on the use-case diagram (check local policy).
All relationships in the use-case description should be depicted on the use-case diagram.
All diagram-specific rules should be enforced.

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Description

Explore the concepts of functional models, including use-case and activity diagrams, which are essential for understanding business processes and system functionality. This quiz will help you grasp the roles of actors and use cases in defining requirements for information systems.