By now, you should be eager to explore the out of the box structured diagram functionality, and perhaps be considering how to create validation rules for your own business. In doing so, I would advise that you always look to build upon what Visio provides—do not try to replicate it! I believe that trying to create your own Shape Data objects, or your own line routing algorithms, for example, is ultimately a waste of time as they will lead you down some dead-ends, some of which still exist within the boxed Visio product. For example, the following three legacy diagram templates in Visio have their own limitations. They are:
The Software and Database|UML Model Diagram solution within Visio is essentially a closed third-party add-on that was purchased, and has seen very little development since then. However, all sets of rules need to be updated from time to time, and so the UML version in Visio will always lag behind those of the leading developers of the UML standard. In addition, there are some elements of the UML solution in Visio that leaves the users constantly frustrated—such as the inability to get at the model composition programmatically.
The Software and Database|Database Model Diagram solution has a few annoyances, such as the inability to print any table or field notes, and the disappearance of any forward engineering capabilities.
The Software and Database|Data Flow Model Diagram solution is one that has been reassessed. We still have the template and stencil for this, but the add-on has not made it through the Microsoft rationalization of Visio add-ons. Therefore, you can now construct DFD models badly without realizing it. We will attempt to remedy this omission in a later chapter by constructing a rule set that can be used with DFD models.
One of the frequently asked questions by a newbie to Visio when confronted by the multiple diagram categories and types is how a particular template is supposed to be used? Often, they are directed to the Visio online help for examples of how to create certain types of diagrams, but this is not always sufficient because they are really asking for automatic assistance as they create the diagram. What they usually want is in fact a guided diagramming system; they require a system that provides them with some feedback on the way that they are composing a diagram. It is easy to drag-and-drop shapes in Visio, to connect them together, to make a diagram pretty with embellishments, or to add text in a variety of ways. However, this loosely-created drawing cannot consistently convey any semantic meaning unless it follows generally accepted rules. It is the imposition of rules that turns a pretty picture into a meaningful mesh of semantic symbology. This is where Microsoft Visio 2010 has made a great advance because it has provided us with the ability to create validation rules for different types of behaviors. In fact, these new features are worthy of a brand new tab, the Process tab, which although automatically applied to several drawing templates, is also available for use on any type of diagram.