Question

Understand the following tools, the steps in creating the tool, and the purpose/usefulness of each: Activity Diagram, Use Case Description, Use Case Diagram, CRC Card, Class Diagram, Sequence Diagrams, Communication Diagram, or Behavioral State Machine. Define it, describe its purpose/usefulness, and list/define the major steps in using the tool. You should be able to illustrate the tool using a scenario.

In depicting a class on a class diagram, each class is shown with 3 parts. Define each part and explain what each part shows. Include an illustration.

Answer 1

ANSWER :

ACTIVITY DIAGRAM

An activity diagram illustrates constant changes taking place in the activity or an event . It is a flowchart that shows  the flow from initial activity to the final activity in the system which can be branched or sequential.

purpose :

- The main purposes of Activity Diagrams is to represent dynamic flow between the various operations (activities).

- Activity diagrams are used to build a working system by making use  of various engineering techniques.

- It helps to determine the order  of activities taking place in the system.

steps : First, make a rough flow mentally and the transform it into activity diagram.

Use Case Description

A use case description describes sequence of actions from initial event to the final event and supports user interaction as well.

purpose :

- It arranges functional requirements of the system

-  It helps to determine the sequence of activities taking place in the system.

- It supports multi-level. Hence, it can use the functional qualities or features of others.

Use Case Diagram

Use Case Diagram is used in system to determine  and arrange the functional requirements of the system. It supports interactions between user and system.

purpose :

- Use cases diagrams explains how the system should work.

- It provides a set of activities that can be used to find out complexity and cost of implementing the system. Based on this, some unwanted events can be eliminated and only functions requirements are being constructed.

steps :

1. Determine the users of the system.
2. Define the functional requirements.
3. For each requirements, find out basic sequence of actions in the system.
4. Describe the basic sequence in the use case description along with alternate actions and make them extend the use case.
5. Classify similarities in the use cases and  Extract them.
6. Repeat steps for all various users of the system.

CRC (Class-Responsibility Collaborator) Card

CRC card depicts classes in the form of presentation. The CRC card includes  class description, attribute values and responsibility.

purpose :

- CRC cards helps in bridging activities.

steps :

- First, make a rough flow mentally and validate design of idea.

- provide its description while drawing CRC Card Diagram.

Class Diagram

It is main strength of object-oriented modeling by representing relation among  different entities (users,object,data etc).

A class diagram denotes the attributes and methods as well as the restrictions put up on to the class.

Class diagrams are used in the modeling of object-oriented systems as they can be mapped to object-oriented languages.

purpose :

- It describes the responsibilities in the course of action taking place in a system

- modeling of object-oriented systems and analyse it.

steps:

-  First, make a rough flow mentally.

- Then transform it into a class diagram.

- describe relations among the entities.

Sequence Diagrams
Sequence diagram shows interactions between objects in the system  in a ordered manner. It is also called as  event diagrams/scenario.

purpose :

- Sequence diagrams describe manner  and order the interacting objects.

- These diagrams can be  used to document new systems.

- These diagrams can be  used to learn functional requirements of the systems.

steps:

-  First, make a rough flow mentally and transform it into a sequence diagram.

Communication Diagram

It depicts an objects with a messages that move from one event to the next.

Purpose :

- It passes message between objects and functionalities of activities.

- It helps to classify the objects and their associated attribute values and events in use cases

steps:

-  First, make a rough flow mentally.

- Then transform it into a communication diagram.

- describe objects and a message.

Behavioral State Machine

It is used to describe  various behaviors in the system through finite state transitions which are initiated by the sequence of actions taking place.

purpose :

- classifies behavioral context and feature for the state machine

steps:

-  First, make a rough flow mentally.

- Then transform it into a state machine diagram.

- describe the transitions occurring in the system.