System Sequence Diagrams

Tutorial

Use-Case for Monopoly game

• Monopoly game• Use Case UC1: Play Monopoly Game• Scope: Monopoly application• Level: user goal• Primary Actor: Person• Stakeholders: Person: Wants to easily

observe the output of the game simulation.

Use-Case for Monopoly game

• Main Success Scenario: • 1. Person enters number of players and requests new game initialization.• 2. Person starts play• 3. System displays game trace for next player move• 4. Repeat step three until a winner or Person cancels.• The following would be part of the supplementary specication in a RUP project:• Domain Specic Rules: The rules for the game are:• Two to eight players can play.• A game is played as a series of rounds on a board comprised by 40 squares. During

a round, each player takes one turn.• In each turn, a player advances his/her piece clockwise around the board a

number of squares equal to the sum of the numbers rolled on two six-sided dice.• After the dice are rolled, the name of the player and the roll are displayed, as well

as the target square's name.

Use-Case Diagram

Domain Model• Remember the key idea of the Domain Model:• A domain model is a representation of real-world conceptual• classes, not of software artifacts. It is not a set of diagrams• describing software classes with responsibilities.• Considering this, a possible Domain model for the given example• would contain:• MonopolyGame• Die• Board• Player• Piece• Square• 5

Domain Model of the Monopoly Game

Sequence Diagram• On Sequence Diagrams:• Time flow is organized from top to bottom.• Focus of control is shown using an activation box

which is optional, but commonly used.• A return from a message may be shown as a dashed

open-arrowed line. Many practitioners exclude them.• Messages sent to self can be illustrated using a nested

activation box.• Conditional messages are shown in square-brackets.

Can be converted to communication diagrams and vice versa.

System Sequence Diagram• On System Sequence Diagrams:• An SSD should be done for the main success scenario of the

use case, and frequent or complex alternative scenarios.• Properties of an SSD:• The UML does not define something called a system

sequence diagram.• SSDs are part of the Use-Case Model (although not• mentioned explicitly within the UP documentation) { a visualisation of the interactions implied in the use cases.• Treat the system as a black-box.• Show user interaction(s) with the system and the actions induced by these.

System Sequence Diagram

Operation Contracts• Contracts in the UML are Operation Specifications.• Help define system behavior.• Contracts describe detailed system behavior in terms of

state changes to objects in the Domain Model.• Usually defined for system operations (identified for

example with an SSD).• Contain pre-conditions to express noteworthy assumptions about the system's state before the operation's execution.• Contain post-conditions which define the state of objects in the Domain Model after completion.

Operation ContractContract C01: initializeOperation: initialize(numberOfPlayers: integer)References: Use Case UC1: Play Monopoly GamePreconditions: Monopoly Game application runningPostconditions: • A Board instance b was created.• b was associated with 40 squares.• 2 dice were created.• The appropriate number of players was created.• A Piece is created and associated with each player.• All pieces were placed on the initial square.

Public Library

• High level format:• Name: search for book• Actors: patron (Initiator), librarian• Type: primary, essential• Description: This use case beginning when patron

come to librarian and ask him about certain book in library by give name of author ,then librarian search in system and tell the patron about department and number of shelf that book founded there.

Expanded format:

• Name: search for book• Actors: patron (Initiator), librarian• Type: primary, essential• Description: This use case beginning when

patron come to librarian and ask him about certain book in library by give name of author ,then librarian search in system and tell the patron about department and number of shelf that book founded there.

Typical course of event:

Actor Action System response

1- This use case beginning when the patron come to library and ask librarian about certain book

2-The librarian asks the patron about name of author book and enters it to the system.

3- The system display all books that written by this author and ask about name of book.

4-the librarian ask the patron about the name of book that written by this author and edition and enter the name to system.

5-The system display the book and position on the library with available number of edition.

6-The librarian ask system to print reportAbout position of book in library.

7-system print the report with all Information about position of book

8-The librarian give the patron the reportWith information of position like:Department, number of shelf

• Alternatives:• Alternative 3: the name of author not exist in

the library so cancel the search• Alternative 5: the name of book not exist in

the library, so cancel searching