Object 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.

The description of object diagram is similar to the description of class diagram.

Definition of objects

You define instance of objects using the object keywords.

object firstObject
object "My Second Object" as o2
simple UML object diagram

Relations between objects

Relations between objects are defined using the following symbols :

Extension <|--
Composition *--
Aggregation o--

It is possible to replace -- by .. to have a dotted line.

Knowing those rules, it is possible to draw the following drawings.

It is possible a add a label on the relation, using " : ", followed by the text of the label.

For cardinality, you can use double-quotes "" on each side of the relation.

object Object01
object Object02
object Object03
object Object04
object Object05
object Object06
object Object07
object Object08

Object01 <|-- Object02
Object03 *-- Object04
Object05 o-- "4" Object06
Object07 .. Object08 : some labels
UML object diagram with relationship

Adding fields

To declare fields, you can use the symbol ":" followed by the field's name.

object user

user : name = "Dummy"
user : id = 123

adding data and fields to UML object diagram
It is also possible to ground between brackets {} all fields.

object user {
  name = "Dummy"
  id = 123

example of object with several fields

Common features with class diagrams