Standard: Layer

Standards: <<layer>>

A specific way of grouping packages in a model at the same level of abstraction.

This type of package is normally an "index", it exists purely for organizational purposes (i.e. like a directory with no entries).

Note the layering may be horizontal or vertical. If preferred the stereotype <<partition>> could be used instead of <<layer>>.

Related Information:

Topics

Naming Standard

The general package naming standards apply to <<layer>> packages (See Standards: Package Overview).

Diagramming Standards

Diagram

Purpose

Use

Comment

Main *1

A class diagram showing the layering / partitioning of the layer and the dependencies between the packages within the layer.

Mandatory

This diagram can often be combined with the Welcome diagram to both introduce the layer and detail its organization in a combined diagram called Main / Welcome.

Dependencies

A class diagram showing which other layers the layer depends on.

Mandatory*

*This diagram is only required if the layer depends on other layers in the model.

Architectural Overview

A class diagram describing the architectural rules for partitioning the layer.

Mandatory

Where the main diagram details the entire contents of the layer, the Architectural Overview diagram focuses on the architectural rules for partitioning the layer and will often only include a subset of the layers contents.

Welcome

A diagram presenting the purpose of the layer.

Optional

An explanatory diagram welcoming users to the layer.

Notes:

*1 - The Main diagram is sometimes referred to as the Organization or Package/Subsystems Dependencies diagram (See the RUP: Rose Tool Mentors).

Constraints

Constraints: <<layer>> packages can only contain other packages.

Notes: layers should only be dependent on other layers. If a model chooses to use layers then the entire static model should be contained within those layers.

Examples

Two example layers are shown with their Main diagrams displayed:

The first example illustrates a layered layer, where the contents of the layer itself is more layers.

The second layer shown is not layered but still only contains other packages (in this case <<subsystem>> and <<utility>> packages).