Component 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 :

Components

Components must be bracketed.

You can also use the component keyword to defines a component. And you can define an alias, using the as keyword. This alias will be used latter, when defining relations.

@startuml

[First component]
[Another component] as Comp2  
component Comp3
component [Last\ncomponent] as Comp4

@enduml

Interfaces

Interface can be defined using the () symbole (because this looks like a circle).

You can also use the interface keyword to defines a usecase. And you can define an alias, using the as keyword. This alias will be used latter, when defining relations.

We will see latter that interface definition is optional.

@startuml

() "First Interface"
() "Another interface" as Interf2
interface Interf3
interface "Last\ninterface" as Interf4

@enduml

Basic example

Links between elements are made using combinaisons of dotted line (..), straight line (--), and arrows (-->) symbols.

@startuml

DataAccess - [First Component] 
[First Component] ..> HTTP : use

@enduml

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

interface "Data Access" as DA

DA - [First Component] 
[First Component] ..> HTTP : use

note left of HTTP : Web Service only

note right of [First Component]
  A note can also
  be on several lines
end note

@enduml

Grouping Components

You can use several keywords to group components and interfaces together:

package
node
folder
frame
cloud
database

@startuml

package "Some Group" {
  HTTP - [First Component]
  [Another Component]
}
 
node "Other Groups" {
  FTP - [Second Component]
  [First Component] --> FTP
} 

cloud {
  [Example 1]
}


database "MySql" {
  folder "This is my folder" {
    [Folder 3]
  }
  frame "Foo" {
    [Frame 4]
  }
}


[Another Component] --> [Example 1]
[Example 1] --> [Folder 3]
[Folder 3] --> [Frame 4]

@enduml

Changing arrows direction

By default, links between classes have two dashes -- and are verticaly oriented. It is possible to use horizontal link by putting a single dash (or dot) like this:

@startuml
[Component] --> Interface1
[Component] -> Interface2
@enduml

You can also change directions by reversing the link:

@startuml
Interface1 <-- [Component]
Interface2 <- [Component]
@enduml

It is also possible to change arrow direction by adding left, right, up or down keywords inside the arrow:

@startuml
[Component] -left-> left 
[Component] -right-> right 
[Component] -up-> up
[Component] -down-> down
@enduml

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 functionnality : 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.

@startuml
title Very simple component\ndiagram

interface "Data Access" as DA

DA - [First Component] 
[First Component] ..> HTTP : use

@enduml

Use UML2 notation

The

skinparam componentStyle uml2

command is used to switch to UML2 notation.

@startuml
skinparam componentStyle uml2

interface "Data Access" as DA

DA - [First Component] 
[First Component] ..> HTTP : use

@enduml

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 components and interfaces.

@startuml

skinparam component {
  FontSize 13
  InterfaceBackgroundColor RosyBrown
  InterfaceBorderColor orange
  BackgroundColor<<Apache>> Red
  BorderColor<<Apache>> #FF6655
  FontName Courier
  BorderColor black
  BackgroundColor gold
  ArrowFontName Impact
  ArrowColor #FF6655
  ArrowFontColor #777777
}

() "Data Access" as DA

DA - [First Component] 
[First Component] ..> () HTTP : use
HTTP - [Web Server] << Apache >>

@enduml