What is Package Diagram

What is Package Diagram?

4-5 minutes

Package diagram, a kind of structural diagram, shows the arrangement and organization of model elements in middle to large scale project. Package diagram can show both structure and dependencies between sub-systems or modules, showing different views of a system, for example, as multi-layered (aka multi-tiered) application – multi-layered application model.

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Purpose of Package Diagrams

Package diagrams are used to structure high level system elements. Packages are used for organizing large system which contains diagrams, documents and other key deliverables.

• Package Diagram can be used to simplify complex class diagrams, it can group classes into packages.
• A package is a collection of logically related UML elements.
• Packages are depicted as file folders and can be used on any of the UML diagrams.

Package Diagram at a Glance

Package diagram is used to simplify complex class diagrams, you can group classes into packages. A package is a collection of logically related UML elements.

The diagram below is a business model in which the classes are grouped into packages:

• Packages appear as rectangles with small tabs at the top.
• The package name is on the tab or inside the rectangle.
• The dotted arrows are dependencies.
• One package depends on another if changes in the other could possibly force changes in the first.

Basic Concepts of Package Diagram

Package diagram follows hierarchal structure of nested packages. Atomic module for nested package are usually class diagrams. There are few constraints while using package diagrams, they are as follows.

• Package name should not be the same for a system, however classes inside different packages could have the same name.
• Packages can include whole diagrams, name of components alone or no component sat all.
• Fully qualified name of a package has the following syntax.

Packages can be represented by the notations with some examples shown below:

Package Diagram – Dependency Notation

There are two sub-types involved in dependency. They are <<import>> & <<access>>.Though there are two stereotypes users can use their own stereotype to represent the type of dependency between two packages.