UML Behavioral Diagram - people.utm.my SE/sequence... · Sequence Diagram. INSPIRING CREATIVE AND...

UML

Behavioral Diagram

Sequence Diagram

INSPIRING CREATIVE AND INNOVATIVE MINDS

• Sequence diagrams show object interactions

arranged in a time sequence

• Sequence diagrams demonstrate the

behavior of objects in a use case by describing

the objects and the messages they pass.

• The diagrams are read left to right and

descending


Sequence Diagram Elements

Execution

Specification

Lifeline

Message


Lifeline & Execution Specification

A lifeline represents an individual participant (or object)

in the interaction

A lifeline is shown using a symbol that consists of a

rectangle forming its “head” followed by a vertical line

(which may be dashed) that represents the lifetime of the

participant

An execution specification specifies a behavior or

interaction within the lifeline

An execution specification is represented as a thin

rectangle on the lifeline.


Messages

Define a particular communication

between lifelines of an interaction

Examples of communication

raising a signal

invoking an operation

creating or destroying an instance


Message Types

sd Interaction

Weather Operator

Weather Station Weather

Controller

Weather Data Instrument

retrieve()

getData()

collect()

get()

sendData()

ok()

ok()

displayData()

Return message

Invoke message


Use Case Analysis-How to find class

i) Method to find objects and their classes:

Begin with the nouns in the requirements specification.

ii) Method to find operations:

Begin with the verbs in the requirements specification.

Example: Computerized Telephone Book For A University

The telephone book should contain entries for each person inthe university community--student, professor, and staffmember. Users of the directory can look up entries. In addition,the administrator of the telephone book can, after supplying apassword, insert new entries, delete existing entries, modifyexisting entries, print the telephone book, and print a listing ofall students or of all faculty.


Use Case Analysis -How to find class

1. Identify the candidate classes. List the nouns and nounphrases from the specification:

computerized telephone book, university, telephone book,entry, person, university community, student, professor, staffmember, employee, user, administrator, password.

2. Identify the candidate operations. List the verbs from thespecification.

lookup entry, supply password, insert new entry, delete existingentry, modify existing entry, print telephone book, print allstudents, print all employees, set telephone number field, gettelephone number field, compare entries.



3. Eliminate unnecessary and synonym classes andoperations.

For example, computerized telephone book, telephone book,and directory can be combined into a single PhoneBook class.

4. Associate the operations with the appropriate classes.

For example, associate lookup, insert, delete, and modify entryoperations with the PhoneBook class, associate compare,setPhoneNumber and getPhoneNumber with the Person class,etc.

During design we should not be concerned with the

minute details of the implementation. However, it is

appropriate to consider whether there is a "reasonable"

implementation.


Boundary class


Example – Boundary class


Entity class


Example – Entity class


Control class


Example – Control class


BoundaryControl BoundaryEntity

Sequence Diagram – Need Improvements?

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Diagram 2

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Diagram 3

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Diagram 4

UML Behavioral Diagram - people.utm.my SE/sequence... · Sequence Diagram. INSPIRING CREATIVE AND...

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