The Agile Modeling (AM) Method

Software Modeling on Plain Old Whiteboards (POWs)

A “plain old whiteboard (POW)” is my favorite modeling tool, and I stand by my claim that whiteboards are the modeling tool with the greatest install base worldwide. In fact throughout this web site you will see many POW sketches, which is nice for an online article or even a book but can are they acceptable for real-world development? My experience is yes, and here are the answers to some common questions that you may have:


1. How Can You Clean Up POW Sketches?

Figure 1 shows a digital photo taken of a POW sketch of a simple use case diagram which I drew with a couple of stakeholders. We took the photo because we were afraid that we’d lose the valuable information that it contains, although I’m sure that we could easily reproduce this diagram in less than a minute if we ever needed to (one of the side benefits of practices such as Depict Models SimplyCreate Simple Content, and Model in Small Increments is that you create models that you can easily reproduce). Digital photos such as this prove to be useful ways to comfort people who think that you need more documentation than you actually do because with the photograph you’ve retained the model – it might not be pretty, but at least you haven’t “lost” the information.

Figure 1. Sketch on a whiteboard.

There are a couple of problems with Figure 1 – the file size is relatively large and it is hard to read because it is so dark. I’m not that worried about file size issues, disk storage is cheap, although large files can be an problem for people with slow network connections. The readability problem is more of an issue for me. Luckily there’s a quick solution, a product called Whiteboard Photo from Polyvision, formerly Pixid. I used this product to create Figure 2 from the original photo, a process which took about two minutes end to end, including the time to run Whiteboard Photo, open the file, clean the photo, and then save it back to disk. One feature of the product is that you can clean many photos at once, something I didn’t do in this case, so you can reduce the average cleaning time even further.

Figure 2. Clean version of the sketch.

Figure 2 isn’t perfect, the blotch in the diagram is the reflection of the flash (the lighting in my work area could be better), but it addresses the problems with Figure 1. I then invested a few minutes with a paint program to produce Figure 3.

Figure 3. Very clean version of the sketch.

An alternative to capturing digital images is to use a manual product such as The Image Saver.


2. Should You Keep the Sketches?

My experience is that you can safely erase 95-99% of all sketches that you create. Then between 95-99% of the diagrams that remain can be photographed and retained that way and a few diagrams I’ll transcribe into a sophisticated software-based modeling tool. These percentages seem to be true for teams familiar with Agile Model Driven Development (AMDD), teams with people who are new to this approach will find that they want to keep more diagrams as it comforts them. Over time experience will teach them to have greater courage and to travel even lighter than they think that they need to, but it takes time to wean people off their “documentation habit”. Digital photos of whiteboards are a radical step for many experienced IT professionals.

Of the photos that I do take, I’ll either stick with the raw photo as you see in Figure 1 or the automatically cleaned up version in Figure 2. It’s important to understand that you’re still investing time, albeit a short time, when using Whiteboard Photo to clean up your diagrams. Remember to Maximize Stakeholder ROI and only do this work if it adds value, and very often it does. The only time that I’ll clean up the diagram further, as you see in Figure 3, is when the diagram is included in some sort of official document such as a presentation to management, a system overview document, or in this case a web site. This clean up step can often be avoided if you work in brightly lit rooms and/or get good at aiming the camera so that the flash appears off to the side of your photo (shoot the picture at an angle).

3. What Are The Trade-offs?

The primary advantages of modeling on POWs are:

  1. They are easy to use.
  2. They are inclusive because practically anyone can use a POW.

The primary disadvantages are:

  1. Whiteboard sketches aren’t permanent, something that you can easily address by taking a digital photo and cleaning it up as appropriate.
  2. It’s hard to update a digital image of a whiteboard photo, you typically have to redraw it if you happened to have erased it from the board, and you can’t do sophisticated things such as generate code from a static, hand-drawn image.
  3. POWs are only a viable option when your team is co-located, something that I highly recommend. When this isn’t the case you’ll need to consider other lean modeling tools.

Notice: This article has been excerpted from The Object Primer 3rd Edition: Agile Modeling Driven Development with UML 2.