Content Modelling - Step 1 - Domain Walkthrough

The process of creating a content model requires a number of steps. It's not just a matter of analyzing the content; the modeler also needs to take into consideration the domain, users, groups, and the relationships between different classes within the model. To do this, we start with a walkthrough of the domain. The client and domain experts walk us through the entire project. This is a vital part of the process. We need to get an understanding of the entire system, not just the part that is captured in the final solution. The model that we end up creating may need to interact with other systems and knowing what they are and how they work will inform the shape of the model. A good example is with e-commerce systems, any information captured on a sale will eventually need to be entered into the existing financial system (whether is it automated or manual).

Without an understanding of the bigger picture, we lack the understanding of how the solution we are creating will fit in with what the business does. That's when there is an existing business process. Sometimes there is no business process and the client is making things up as they go along, e.g. they have decided to do online shopping but they have never dealt with overseas orders so don't know how that will work and have no idea how they would deal with shipping costs.

One of the typical problems that will surface during the domain walkthrough is that the client will try to tell you how they want the solution to work. By doing this, they are actually defining the model and interactions. This is something to be wary of. It is unlikely that they would be aware of how best to structure a solution; what you want to be asking is what they currently do, what's their current business process. You want to deal with facts that are in existence so that you can decide how best to model the solution.

To get the client back on track ask questions like:

  • How do you currently do "it" (i.e. the business process)?

  • What information to you currently capture?

  • How do you capture that information?

  • What format is that information in?

  • How often is the information updated?

  • Who updates it?

This gives you a picture of what is currently happening. Then you can start to shape the model to ensure that you are dealing with the real world, not what the client thinks they want. Sometimes they won't be able to answer the question and you'll have to get the right person from the business involved to get the answers you want. Sometimes you discover that what the client thought was happening is not really what happens.

Another benefit of this process is gaining a common understanding. If both you and the client are in the room when the process for calculating shipping costs is being explained by the Shipping Manager, you'll both appreciate how complex the process is. If the client thinks it's easy, they won't expect it to cost much. If they are in the room when the shipping manager explains there are five different shipping methods and each has its own way of calculating the costs for a shipment based on their own set of international zones, you know modeling that part of the system is not going to be straightforward unlike what the client initially thought.

What this means is that the domain walkthrough gives you a sense of what's real, not what people think the situation is. It's the most important part of the process. Assumptions that "shipping costs" are straightforward, so you don't need to worry about that, can be a disaster later down the track when you find out it's not the case.

Also, don't necessarily rely on requirements documents (unless you have written them yourself). A statement in a requirements document may not reflect what really happens; that's why you want to make sure you go through everything to confirm that you have all the facts. Sometimes, a particular requirement can be stated in the document but when you go through it in more detail, ask a few questions, pose a few scenarios, the client changes their mind on what it is that they really want as they realize what they thought they wanted is going to be difficult or expensive to implement. Or, you put an alternative approach to them and they are happy to achieve the same result in a different manner that is easier to implement. This is a valuable way to work out what's real and what really matters.