Add custom architecture validation to layer diagrams

In Visual Studio, users can validate the source code in a project against a layer model so that they can verify that the source code conforms to the dependencies on a layer diagram. There is a standard validation algorithm, but you can define your own validation extensions.

When the user selects the Validate Architecture command on a layer diagram, the standard validation method is invoked, followed by any validation extensions that have been installed.

You can package your layer validation extension into a Visual Studio Integration Extension (VSIX), which you can distribute to other Visual Studio users. You can either place your validator in a VSIX by itself, or you can combine it in the same VSIX as other extensions. You should write the code of the validator in its own Visual Studio project, not in the same project as other extensions.

Requirements

See Requirements.

Defining a Layer Validator in a New VSIX

The quickest method of creating a validator is to use the project template. This places the code and the VSIX manifest into the same project.

To define an extension by using a project template

1. Create a project in a new solution, by using the New Project command on the File menu.

2. In the New Project dialog box, under Modeling Projects, select Layer Designer Validation Extension.

   The template creates a project that contains a small example.

   Warning

   To makethe template work properly:

   • Edit calls to LogValidationError to remove the optional arguments errorSourceNodes and errorTargetNodes.
     • If you use custom properties, apply the update mentioned in Add custom properties to layer diagrams.

3. Edit the code to define your validation. For more information, see Programming Validation.

4. To test the extension, see Debugging Layer Validation.

   Note

   Your method will be called only in specific circumstances, and breakpoints will not work automatically. For more information, see Debugging Layer Validation.

5. To install the extension in the main instance of Visual Studio, or on another computer, find the .vsix file in bin\. Copy it to the computer where you want to install it, and then double-click it. To uninstall it, use Extensions and Updates on the Tools menu.

Adding a Layer Validator to a Separate VSIX

If you want to create one VSIX that contains layer validators, commands, and other extensions, we recommend that you create one project to define the VSIX, and separate projects for the handlers. For information about other types of modeling extension, see Extend UML models and diagrams.

To add layer validation to a separate VSIX

1. Create a Class Library project in a new or existing Visual Studio solution. In the New Project dialog box, click Visual C# and then click Class Library. This project will contain the layer validation class.

2. Identify or create a VSIX project in your solution. A VSIX project contains a file that is named source.extension.vsixmanifest. If you have to add a VSIX project, follow these steps:

   1. In the New Project dialog box, choose Visual C#, Extensibility, VSIX Project.

   2. In Solution Explorer, on the shortcut menu of the VSIX project, Set as Startup Project.

3. In source.extension.vsixmanifest, under Assets, add the layer validation project as a MEF component:

   1. Choose New.

   2. In the Add New Asset dialog box, set:

      Type = Microsoft.VisualStudio.MefComponent

      Source = A project in current solution

      Project = your validator project

4. You must also add it as a layer validation:

   1. Choose New.

   2. In the Add New Asset dialog box, set:

      Type = Microsoft.VisualStudio.ArchitectureTools.Layer.Validator. This is not one of the options in the drop-down list. You must enter it from the keyboard.

      Source = A project in current solution

      Project = your validator project

5. Return to the layer validation project, and add the following project references:

   Reference	What this allows you to do
   Microsoft.VisualStudio.GraphModel.dll	Read the architecture graph
   Microsoft.VisualStudio.ArchitectureTools.Extensibility.CodeSchema.dll	Read the code DOM associated with layers
   Microsoft.VisualStudio.ArchitectureTools.Extensibility.Layer.dll	Read the Layer model
   Microsoft.VisualStudio.ArchitectureTools.Extensibility	Read and update shapes and diagrams.
   System.ComponentModel.Composition	Define the validation component using Managed Extensibility Framework (MEF)
   Microsoft.VisualStudio.Modeling.Sdk.[version]	Define modeling extensions

6. Copy the example code at the end of this topic into the class file in the validator library project to contain the code for your validation. For more information, see Programming Validation.

7. To test the extension, see Debugging Layer Validation.

   Note

   Your method will be called only in specific circumstances, and breakpoints will not work automatically. For more information, see Debugging Layer Validation.

8. To install the VSIX in the main instance of Visual Studio, or on another computer, find the .vsix file in the bin directory of the VSIX project. Copy it to the computer where you want to install the VSIX. Double-click the VSIX file in Windows Explorer. (File Explorer in Windows 8.)

   To uninstall it, use Extensions and Updates on the Tools menu.

Programming Validation

To define a layer validation extension, you define a class that has the following characteristics:

• The overall form of the declaration is as follows:

  
  using System.ComponentModel.Composition;
  using Microsoft.VisualStudio.ArchitectureTools.Extensibility.CodeSchema;
  using Microsoft.VisualStudio.ArchitectureTools.Extensibility.Layer;
  using Microsoft.VisualStudio.GraphModel;
  ...
  [Export(typeof(IValidateArchitectureExtension))]
    public partial class Validator1Extension :
                    IValidateArchitectureExtension
    {
      public void ValidateArchitecture(Graph graph)
      {
         GraphSchema schema = graph.DocumentSchema;
        ...
    } }
  

• When you discover an error, you can report it by using LogValidationError().

  Warning

  Do not use the optional parameters of LogValidationError.

  When the user invokes the Validate Architecture menu command, the layer runtime system analyses the layers and their artifacts to produce a graph. The graph has four parts:

• The layer models of the Visual Studio solution that are represented as nodes and links in the graph.

• The code, project items, and other artifacts that are defined in the solution and represented as nodes, and links that represent the dependencies discovered by the analysis process.

• Links from the layer nodes to the code artifact nodes.

• Nodes that represent errors discovered by the validator.

  When the graph has been constructed, the standard validation method is called. When this is complete, any installed extension validation methods are called in unspecified order. The graph is passed to each ValidateArchitecture method, which can scan the graph and report any errors that it finds.

Validation methods should not change the layer model or the code that is being validated.

The graph model is defined in Microsoft.VisualStudio.GraphModel. Its principal classes are GraphNode and GraphLink.

Each Node and each Link has one or more Categories which specify the type of element or relationship that it represents. The nodes of a typical graph have the following categories:

• Dsl.LayerModel

• Dsl.Layer

• Dsl.Reference

• CodeSchema_Type

• CodeSchema_Namespace

• CodeSchema_Type

• CodeSchema_Method

• CodeSchema_Field

• CodeSchema_Property

  Links from layers to elements in the code have the category "Represents".

Debugging Validation

To debug your layer validation extension, press CTRL+F5. An experimental instance of Visual Studio opens. In this instance, open or create a layer model. This model must be associated with code, and must have at least one dependency.

Test with a Solution that contains Dependencies

Validation is not executed unless the following characteristics are present:

• There is at least one dependency link on the layer diagram.

• There are layers in the model that are associated with code elements.

  The first time that you start an experimental instance of Visual Studio to test your validation extension, open or create a solution that has these characteristics.

Run Clean Solution before Validate Architecture

Whenever you update your validation code, use the Clean Solution command on the Build menu in the experimental solution, before you test the Validate command. This is necessary because the results of validation are cached. If you have not updated the test layer diagram or its code, the validation methods will not be executed.

Launch the Debugger Explicitly

Validation runs in a separate process. Therefore, the breakpoints in your validation method will not be triggered. You must attach the debugger to the process explicitly when validation has started.

To attach the debugger to the validation process, insert a call to System.Diagnostics.Debugger.Launch() at the start of your validation method. When the debugging dialog box appears, select the main instance of Visual Studio.

Alternatively, you can insert a call to System.Windows.Forms.MessageBox.Show(). When the message box appears, go to the main instance of Visual Studio and on the Debug menu click Attach to Process. Select the process that is named Graphcmd.exe.

Always start the experimental instance by pressing CTRL+F5 (Start without Debugging).

Deploying a Validation Extension

To install your validation extension on a computer on which a suitable version of Visual Studio is installed, open the VSIX file on the target computer. To install on a computer on which Team Foundation Build is installed, you must manually extract the VSIX contents into an Extensions folder. For more information, see Deploy a layer model extension.

Example code

using System;
using System.ComponentModel.Composition;
using System.Globalization;
using System.Linq;
using System.Text.RegularExpressions;
using Microsoft.VisualStudio.ArchitectureTools.Extensibility.CodeSchema;
using Microsoft.VisualStudio.ArchitectureTools.Extensibility.Layer;
using Microsoft.VisualStudio.GraphModel;

namespace Validator3
{
    [Export(typeof(IValidateArchitectureExtension))]
    public partial class Validator3Extension : IValidateArchitectureExtension
    {
        /// <summary>
        /// Validate the architecture
        /// </summary>
        /// <param name="graph">The graph</param>
        public void ValidateArchitecture(Graph graph)
        {
            if (graph == null) throw new ArgumentNullException("graph");

            // Uncomment the line below to debug this extension during validation
            // System.Windows.Forms.MessageBox.Show("Attach 2 to GraphCmd.exe with process id " + System.Diagnostics.Process.GetCurrentProcess().Id);

            // Get all layers on the diagram
            foreach (GraphNode layer in graph.Nodes.GetByCategory("Dsl.Layer"))
            {
                System.Threading.Thread.Sleep(100);
                // Get the required regex property from the layer node
                string regexPattern = "^[a-zA-Z]+$"; //layer[customPropertyCategory] as string;
                if (!string.IsNullOrEmpty(regexPattern))
                {
                    Regex regEx = new Regex(regexPattern);

                    // Get all referenced types in this layer including those from nested layers so each
                    // type is validated against all containing layer constraints.
                    foreach (GraphNode containedType in layer.FindDescendants().Where(node => node.HasCategory("CodeSchema_Type")))
                    {
                        // Check the type name against the required regex
                        CodeGraphNodeIdBuilder builder = new CodeGraphNodeIdBuilder(containedType.Id, graph);
                        string typeName = builder.Type.Name;
                        if (!regEx.IsMatch(typeName))
                        {
                            // Log an error
                            string message = string.Format(CultureInfo.CurrentCulture, Resources.InvalidTypeNameMessage, typeName);
                            this.LogValidationError(graph, typeName + "TypeNameError", message, GraphErrorLevel.Error, layer);
                        }
                    }
                }

            }

        }
    }
}

See Also

Extend layer diagrams