Introduction to Diagrams

Introduction to UML Diagrams 

• Using UML, we build models from basic building blocks like classes, interfaces, collaborations, components, nodes and relationships 
• We normally render these models by the means of diagrams 
• Diagram is a graphical presentation of a set of elements 
• Diagrams have static and dynamic parts 
• UML diagrams are used in two ways 

An executable system can be constructed from models (Forward engineering)  From the parts of an executable system, models are reconstructed

Click Here to View UML Diagrams

Modeling Different Views of a System

To model a system from different views: 

Select the views that are needed to best convey the architecture of the system and represent technical risks to the project. 

• For each of the views, select the artifacts that need to be created to describe the essential details of that particular view 
• Decide which diagrams are to be preserved for the future and which can be thrown away

Modeling Different Levels of Abstraction 

To model a system at different levels of abstraction by presenting diagrams with different levels of detail. 

• Begin with a model based on needs 

If the model is used to build an implementation, detailed diagrams are needed  If the model is used to communicate a conceptual model to an end-user, high-level diagrams are better-suited

To model a system at different levels of abstraction by creating models at different levels of abstraction.

Generate a diagram at the right level of abstraction by hiding or showing: 

Building blocks and relationships: Hide those are not necessary to the purpose of the diagram  Adornments: Display only those that are necessary to understand the intent  Flow: Expand only those messages or transitions that are relevant for the purpose  Stereotypes: Show only the ones that are essential to understand the intent

To model a system by creating models at different levels of abstraction: 

• Model detailed abstractions for low-level details and simple abstractions for high-level of abstraction 
• Depict dependencies needed to trace between elements of different models. The common situations in the 4+1 view of architecture are 

• Use cases and their realization: Use cases in a use case model will trace to collaborations in a design model 
• Collaborations and their realization: Collaborations will trace to a society of classes that implement the collaboration

Modeling Complex Views 

To model complex views: 

• Some parts of the diagram can be hidden and the details in other parts can be preserved, when there is no suitable way of presenting this information at a higher level of abstraction
• Consider combining some of the elements in packages or in higher-level collaborations if the diagram is still complicated 
• Later, render these packages in the diagram 
• Nodes and colors can be used as visual clues to simplify the diagram and yet emphasize important points 

Diagrams at Glance