Table of Contents
Use Case Diagram
To be able to generate those diagrams, you must have Graphviz_software installed on your machine in the default directory c:\Program Files\GraphvizX.XX or /usr/bin/dot. You can have_a_look_here_if_you_have_installed_Graphviz_somewhere_else. Let's have a fews examples : Note that you can disable the shadowing using the skinparam shadowing false command.
Usecases
Use cases are enclosed using between parentheses (because two parentheses looks like an oval). You can also use the usecase keyword to define a usecase. And you can define an alias, using the as keyword. This alias will be used latter, when defining relations. <uml t=“usecase”>
(First usecase) (Another usecase) as (UC2) usecase UC3 usecase (Last\nusecase) as UC4
</uml>
Actors
Actor are enclosed using between two points. You can also use the actor keyword to define an actor. And you can define an alias, using the as keyword. This alias will be used latter, when defining relations. We will see later that the actor definitions are optional. <uml t=“usecase_001”>
:First Actor: :Another\nactor: as Men2 actor Men3 actor :Last actor: as Men4
</uml>
Usecases description
If you want to have description on several lines, you can use quotes. You can also use the following separators: – .. == __. And you can put titles within the separators. <uml t=“usecase_002”>
usecase UC1 as “You can use several lines to define your usecase. You can also use separators. – Several separators are possible. == And you can add titles: ..Conclusion.. This allows large description.”
</uml>
Basic example
To link actors and use cases, the arrow –> is used. The more dashes “-” in the arrow, the longer the arrow. You can add a label on the arrow, by adding a “:” character in the arrow definition. In this example, you see that User has not been defined before, and is used as an actor. <uml t=“usecase_003”>
User → (Start) User –> (Use the application) : A small label
:Main Admin: —> (Use the application) : This is\nyet another\nlabel </uml>
Extension
If one actor/use case extends another one, you can use the symbol <|– (which stands for [img/extends01.png]). <uml t=“usecase_004”> :Main Admin: as Admin (Use the application) as (Use)
User <|– Admin (Start) <|– (Use)
</uml>
Using notes
You can use the note left of , note right of , note top of , note bottom of keywords to define notes related to a single object. A note can be also define alone with the note keywords, then linked to other objects using the .. symbol. @startuml :Main Admin: as Admin (Use the application) as (Use)
User → (Start) User –> (Use)
Admin —> (Use)
note right of Admin : This is an example.
note right of (Use)
A note can also be on several lines
end note
note “This note is connected\nto several objects.” as N2 (Start) .. N2 N2 .. (Use) </uml>
[imgp/usecase_005.png]
Stereotypes
You can add stereotypes while defining actors and use cases using “ « ” and “
”.
<uml t=“usecase_006”> User « Human » :Main Database: as MySql « Application » (Start) « One Shot » (Use the application) as (Use) « Main »
User → (Start) User –> (Use)
MySql –> (Use)
</uml>
Changing arrows direction
By default, links between classes have two dashes – and are vertically oriented. It is possible to use horizontal link by putting a single dash (or dot) like this: <uml t=“usecase_007”> :user: –> (Use case 1) :user: → (Use case 2) </uml> You can also change directions by reversing the link: <uml t=“usecase_008”> (Use case 1) <.. :user: (Use case 2) ← :user: </uml> It is also possible to change arrow direction by adding left, right, up or down keywords inside the arrow: <uml t=“usecase_009”> :user: -left→ (dummyLeft) :user: -right→ (dummyRight) :user: -up→ (dummyUp) :user: -down→ (dummyDown) </uml> You can shorten the arrow by using only the first character of the direction (for example, -d- instead of -down-) or the two first characters (-do-). Please note that you should not abuse this functionality : Graphviz gives usually good results without tweaking.
Title the diagram
The title keywords is used to put a title. You can use title and end title keywords for a longer title, as in sequence diagrams. <uml t=“usecase_010”> title Simple <b>Usecase</b>\nwith one actor
“Use the application” as (Use) User → (Use)
</uml>
Splitting diagrams
The newpage keywords to split your diagram into several pages or images. <uml t=“usecase_011_001”> :actor1: –> (Usecase1) newpage :actor2: –> (Usecase2) </uml>
Left to right direction
The general default behavior when building diagram is top to bottom. <uml t=“usecase_012”> 'default top to bottom direction user1 –> (Usecase 1) user2 –> (Usecase 2)
</uml> You may change to left to right using the left to right direction command. The result is often better with this direction. <uml t=“usecase_013”>
left to right direction user1 –> (Usecase 1) user2 –> (Usecase 2)
</uml>
Skinparam
You can use the skinparam command to change colors and fonts for the drawing. You can use this command :
- In the diagram definition, like any other commands,
- In an included_file,
- In a configuration file, provided in the command_line or the ANT_task.
You can define specific color and fonts for stereotyped actors and usecases. <uml t=“usecase_014”>
skinparam usecase {
BackgroundColor DarkSeaGreen BorderColor DarkSlateGray
BackgroundColor<< Main >> YellowGreen BorderColor<< Main >> YellowGreen ArrowColor Olive ActorBorderColor black ActorFontName Courier
ActorBackgroundColor<< Human >> Gold
}
User « Human » :Main Database: as MySql « Application » (Start) « One Shot » (Use the application) as (Use) « Main »
User → (Start) User –> (Use)
MySql –> (Use)
</uml>
Complete example
<uml t=“usecase_015”> left to right direction skinparam packageStyle rect actor customer actor clerk rectangle checkout {
customer -- (checkout) (checkout) .> (payment) : include (help) .> (checkout) : extends (checkout) -- clerk
} </uml>
