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CS 3203 Software Engineering Lab 4
CS 3203 Software Engineering Lab 4
Course
Software Engineering (CS391)
174 Documents
Students shared 174 documents in this course
University
Fayoum University
Academic year: 2021/2022
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Systems models
3. Sequence Diagram
▪ Sequence diagrams are used to model the interactions between the actors and the objects
within a system.
▪ Sequence diagrams describe interactions among classes in terms of an exchange of
messages over time.
Basic Sequence Diagram Symbols and Notations:
Class roles
▪ Class roles describe the way an object will behave in context. Use the UML object symbol to
illustrate class roles, but don't list object attributes.
Activation
▪ Activation boxes represent the time an object needs to complete a task.
Messages
Messages are arrows that represent communication between objects. Use half-arrowed lines to
represent asynchronous messages. Asynchronous messages are sent from an object that will not
wait for a response from the receiver before continuing its tasks.
CS 3203 Software Engineering (1) – 2020/2021 Lab (4)
Lifelines
▪ Lifelines are vertical dashed lines that indicate the object's presence over time.
Example:
Login system
Example 2:
weather stations are deployed in remote areas. Each weather station records local weather
information and periodically transfers this to a weather information system, using a satellite link.
1 SatComms object receives a request from the weather information system to collect a
weather report from a weather station. It acknowledges receipt of this request.
2. SatComms sends a message to WeatherStation, via a satellite link, to create a summary of the
collected weather data.
3. WeatherStation sends a message to a Commslink object to summarize the weather data.
4. Commslink calls the summarize method in the object WeatherData and waits for a reply.
Example 3:
Drawing the sequence diagram, it’s necessary to identify the objects or actors that would be
involved in creating a new user account. These would be;
- Librarian
- Online Library Management system
- User credentials database
- Email system
Here are the steps that occur in the use case named ‘Create New Library User Account’.
- The librarian requests the system to create a new online library account
- The librarian then selects the library user account type
- The librarian enters the user’s details
- The user’s details are checked using the user Credentials Database
- The new library user account is created
- A summary of the of the new account’s details are then emailed to the user
From each of these steps, you can easily specify what messages should be exchanged between the
objects in the sequence diagram. Once it’s clear, you can go ahead and start drawing the sequence
diagram.
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CS 3203 Software Engineering Lab 4
Course: Software Engineering (CS391)
174 Documents
Students shared 174 documents in this course
University: Fayoum University
Was this document helpful?
Eng. Yossr - Eng. Esraa
1
Systems models
3. Sequence Diagram
▪ Sequence diagrams are used to model the interactions between the actors and the objects
within a system.
▪ Sequence diagrams describe interactions among classes in terms of an exchange of
messages over time.
Basic Sequence Diagram Symbols and Notations:
Class roles
▪ Class roles describe the way an object will behave in context. Use the UML object symbol to
illustrate class roles, but don't list object attributes.
Activation
▪ Activation boxes represent the time an object needs to complete a task.
Messages
Messages are arrows that represent communication between objects. Use half-arrowed lines to
represent asynchronous messages. Asynchronous messages are sent from an object that will not
wait for a response from the receiver before continuing its tasks.
CS 3203 Software Engineering (1) – 2020/2021
Lab (4)
