A beginner's introduction to UML Diagramming

While there are many types of UML diagrams, let’s concentrate on the building blocks of UML Diagrams here. The building blocks can be defined as :

  1. Things
  2. Relationships
  3. Diagrams


These are known as the most important buildings blocks of UML. Things can be further divided into :

  1. Structural
  2. Behavioural
  3. Grouping
  4. Annotational

The static parts of a model are defined as structural things. The latter can be defined as conceptual and physical elements. These structural things are defined below :

Class - This defines an object set that possess responsibilities that are similar.

Interface - This indicates a set of operations that would detail the responsibility of a class.

Usecase - This is representative of a set of actions, which are performed by a system that is goal specific.

Component - This physical part of a system is defined as the Component.

Node - A node is indicated as a physical element, which is usually present during run time.


Behavioural things encapsulates the dynamic parts of all UML Models. These behavioural things are shown below :

Interaction - This is known as a behaviour, which consists of messages that are exchanged among certain elements to finish a task that is specific.

State Machine - This is something that is useful when the state of an object in its life cycle is significant. This is concerned with the sequence of states an object goes through in reply to events, which are external factors that are responsible for state change.


This is considered as a device where elements of a UML Model can be grouped together. Consequently, there is only one thing under this section that is available.

Package - A package is available for gathering behavioural and structural things.


This is defined as a way to capture remarks, descriptions and comments of UML model elements. Like Grouping, there is only one thing available under this section.

Comment - A comment is used to deliver things like notes and constraints of an element.

Now let's discuss the second type of building block, i.e Relationships in UML diagrams.


The next most important building blocks of UML modelling are the Relationships that are depicted in a UML Diagram. Relationships tell us what elements are associated with each other. This type of association describes the particular functionality of applications. The different types of relationships are listed below :

Dependency - This is a relationship that exists between two things where a change in one element may affect the other one.

Association - This is a set of links, which connects elements of a UML model. This type of relationship also illustrates how many instances of an object are involved in that relationship.

Generalization - A Generalization is defined as a relationship that makes a connection between a specialized element and a generalized element. This describes an inheritance relationship within the world of objects whereby a specialized object will inherit the behaviours and properties of the generalized parent object.

Realization - A Realization is a little different from the other relationships mentioned above. Realization depicts the relationship between an interface and an implementation of a class. A responsibility is described by one element while the other implements it.

The third type of building blocks is the UML Diagrams. You can read on the different types of UML diagrams from here.

Image from - http://www.sba.oakland.edu/undergrad

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