Exercise 1: Introduction to Class Dependency Graphs
In this exercise, you will learn how to generate and navigate a class dependency graph.
- Log in as Abu Obeida Bakhach (Dev) if you have not already done so. The password is P2ssw0rd (capital letter P, the number two, the letter s, the letter s, the letter w, the number zero, the letter r, and the letter d). Please see “Working with the Visual Studio 2010 Virtual Machine” for instructions on how to log into the VM.
- Open Microsoft Visual Studio from Start | All Programs | Microsoft Visual Studio 2010 | Microsoft Visual Studio 2010.
- In Source Control Explorer (View | Other Windows | Source Control Explorer), navigate to Tailspin Toys | Development | Iteration 2 and double-click on the TailspinToys.sln file to open the Tailspin Toys solution.
- Rebuild the solution (Build | Rebuild Solution from the main menu). This step may take a few minutes to complete.
- Close the Output window after the build has successfully completed.
- Create a new class dependency graph (Architecture | Generate Dependency Graph | By Class). The class dependency graph is stored in a Directed Graph Markup Language format (hereafter referred to as DGML), which allows you to work with it using Visual Studio 2010 as well as other standard tools.
Generating the class dependency graph for all projects in the solution may take a minute to complete.
Select the Quick Clusters button from the Directed Graph toolbar to view all classes and their relationships at a glance.
Figure 1
Quick Clusters layout button location
Figure 2
Quick Clusters view of generated class dependency graph
The generated dependency graph views that you see may be different from the screenshots shown in this lab manual. You may need to perform additional zooming, scrolling, and visually searching for objects specified in the lab steps.
The Quick Clusters layout view of this class dependency graph only gives us an idea of the number of classes in all TailspinToys projects and their degree of dependency between each other. This is of limited usefulness to us, so zoom in towards the center of the graph by holding down the Ctrl key and using the mouse scroll wheel until you can clearly see the Product class.
Zooming can also be done using the Zoom drop down box in the Directed Graph toolbar, or alternatively by using the + and – magnifying glass icons next to the Zoom drop down.
Figure 3
Close up view of class dependency graph showing the Product class
Gray lines of varying thicknesses represent the magnitude of relationship interdependencies between classes, with thicker lines equating to more relationships.
Select the Product class by left-clicking on it to highlight only the direct relationships (purple color) between the Product class and the other classes represented in the graph.
Figure 4
Product class selected showing direct relationship lines
Selecting the Product class node from the graph helps highlight its direct relationship to other classes, but it is still difficult to distinguish between incoming and outgoing dependency relationships. To help visually make this distinction, change the graph layout by selecting the Top to Bottom button from the Directed Graph toolbar.
Figure 5
Top to Bottom layout button location
Figure 6
Result of Top to Bottom layout
The top to bottom layout shows incoming dependency relationship lines on the top and outgoing lines on the bottom. This is an improvement, but there is still a lot of visual noise from dependency relationships between the other classes (shown in gray). Select the Butterfly Mode button to hide the relationship lines that do not live on a path through the selected Product node.
Figure 7
Butterfly Mode button location
Figure 8
Butterfly Mode view
We can simplify the visualization of dependency relationships and classes even further by choosing the depth to branch out. Select the Neighborhood Browse Mode button from the Directed Graph toolbar and select the 1 Link option.
Figure 9
Neighborhood Browse Mode button location
Figure 10
Result of Neighborhood Browse Mode with 1 Link
Select the Quick Clusters layout button to return to the clusters layout view.
Figure 11
Quick Clusters layout button location
Zoom out as necessary to fit the entire graph into view.
Figure 12
Quick Clusters view showing direct dependencies between Product and other classes
Locate the OrderLine class node and hover the mouse cursor over the purple relationship line that connects to the Product class node. When the navigation control appears, click on the + button to see the details of this relationship. This will start the process of generating a new dependency graph.
Figure 13
Location of + button to create a new graph
The navigation control that appears when hovering over a purple relationship line exposes three actions. The two arrows navigate to either the source or the target node of the relationship (depending upon context). The + button will help you generate a new graph with just the source and target nodes.
In the Generate Dependency Graph window, only include Types and Methods. We will leave Assemblies, Namespaces, and Externals out of the new graph. Select the option to Show Containment as group and select the OK button to generate the new graph.
Figure 14
Generate Dependency Graph options
Figure 15
Initial view of generated dependency graph
- Let’s expand on this initial view by right-clicking and selecting Group | Expand All.
Select the Top to Bottom layout button.
Figure 16
Expanded dependency graph
So far, the only additional thing that we have learned about the relationship between these two classes is the methods that are involved. To see more details about the relationship between the methods, select the Dependency Matrix View button.
Figure 17
Dependency Matrix View button location
Figure 18
Dependency matrix view
- The dependency matrix view allows sorting rows or columns by display name. Select the Sort Rows by Display Name button just to the right of the Dependency Matrix View button.
- The dependency matrix view currently shows the relationship going from the OrderLine class to the Product class, as you can see from the arrow direction in Figure 15.
Another option that you have is to use the Reflexive view in order to see the relationships regardless of the direction. Select the Show Reflexive View button.
Figure 19
Show Reflexive View button location
Figure 20
Reflexive view of dependency matrix
Next Step
Exercise 2: Discovering Circular References