Layer Diagrams: Reference

In Visual Studio Ultimate, you can use a layer diagram to visualize the high-level, logical architecture of your system. A layer diagram organizes the physical artifacts in your system into logical, abstract groups called layers. These layers describe major tasks that the artifacts perform or the major components of your system. Each layer can also contain nested layers that describe more detailed tasks. 

You can specify the intended or existing dependencies between layers. These dependencies, which are represented as arrows, indicate which layers can use or currently use the functionality represented by other layers. By organizing your system into layers that describe distinct roles and functions, a layer diagram can help make it easier for you to understand, reuse, and maintain your code.

Use a layer diagram to help you perform the following tasks:

• Communicate the existing or intended logical architecture of your system.

• Discover conflicts between your existing code and the intended architecture.

• Visualize the impact of changes on the intended architecture when you refactor, update, or evolve your system.

• Reinforce the intended architecture during the development and maintenance of your code by including validation with your check-in and build operations.

This topic describes the elements that you can use on a layer diagram. For more detailed information about how to create and draw layer diagrams, see Layer Diagrams: Guidelines. For more information about layering patterns, see the Patterns & Practices site at https://go.microsoft.com/fwlink/?LinkId=145794.

Reading Layer Diagrams

The following table describes the elements that you can use on a layer diagram.

Layer Explorer

You can link each layer to artifacts in your solution, such as projects, classes, namespaces, project files, and other parts of your software. The number on a layer shows the number of artifacts that are linked to the layer. However, when reading the number of artifacts on a layer, remember the following:

• If a layer links to an artifact that contains other artifacts, but the layer does not link directly to the other artifacts, then the number includes only the linked artifact. However, the other artifacts are included for analysis during layer validation.

  For example, if a layer is linked to a single namespace, then the number of linked artifacts is 1, even if the namespace contains classes. If the layer also has links to each class in the namespace, then the number will include the linked classes.

• If a layer contains other layers that are linked to artifacts, then the container layer is also linked to those artifacts, even though the number on the container layer does not include those artifacts.

For more information about linking layers and artifacts, see:

• Layer Diagrams: Guidelines

• How to: Create Layer Diagrams from Artifacts

To examine the linked artifacts

• On the layer diagram, right-click one or more layers, and then click View Links.

  Layer Explorer opens and shows the artifacts that are linked to the selected layers. Layer Explorer has a column that shows each of the properties of the artifact links.

  Note

  If you cannot see all of these properties, expand the Layer Explorer window.

  Column in Layer Explorer	Description
  Categories	The kind of artifact, such as a class, namespace, source file, and so on
  Layer	The layer that links to the artifact
  Supports Validation	If True, then the layer validation process can verify that the project conforms to dependencies to or from this element. If False, then the link does not participate in the layer validation process. For more information, see Layer Diagrams: Guidelines.
  Identifier	The reference to the linked artifact

See Also

Concepts

Developing Models for Software Design