requirements management, the php way

In typical PHP projects, people are afraid of spending more hours in development that actually planned. As a main reason for this exceeding the estimated (thus paid) budget of hours, usually "technical problems" are given. But the experience (and some empirical studies) show that this is not really true: Especially for bigger projects (>100 person days) a much bigger danger lies in understanding the requirements right. Of course we work iteratively and of course we re-estimate each feature right before we start implementig it. But our customers have internal processes and thus they need to scope the project  very detailed upfront. So we need to tell them what we will deliver and what cost are involved with it. Actually, what we need is an adapted form of planning game as described in agile methods: We need to gather all functional requirements from an unstructured document and we need to roughly estimate on a basis of these requirements in order to define features and scope the project right.

There are a lot of books about classical requirements management for the usual waterfall project model. In the PHP world, things are more dynamic and change more often. We have solved this problem for a quite big project currently. Our PHP-minded approach looks like this:

1. We get a functional requirements document from the customer. This is his "wishlist"

2. We derive the actual requirements from this document. This is important because the customer tends to distribute similar requirements via the whole specification and thus, the structure of his document is usually not suitable for our project organisation.

We list the requirements in an excel sheet that has the following columns:

- Chapter in the original document of the customer
- Brief description of the feature
- Rough first estimation of the development effort (we use person days, but you could also use "feature points")
- Comment field for assumptions regarding the estimation
- a feature number and feature name

While we isolate requirements, we immediately associate them with features. If no feature had been defined before that matches the new requirement, we add a new one. In excel that is easy: just type a new feature name, the completion feature of excel helps to aviod mis-spelling when referring to a previously defined feature. Feature numbers we assign in a separate list and also write to our requirements list.

We put every requirement we find into the list. Even if it is double (i.e. mentioned in a different chapter). This way, we build a relation between chapters in the requirements document and our feature numbers.

3. Now we sort the list by feature. After that we see all the requirements that were redundant. We keep them in the list, but reduce the estimated hours if the redundant ones to 0. This way we keep the relation but avoid doubling the estimated cost.

4. My new favorite feature in Excel: Pivot Tables. I am not a microsoft fan, but this is really cool: Excel can aggregate all estimated hours per feature in such a table. The result is a list if disctinct features with the associated estimated days.

5. This table we can then discuss with the customer. We know where the effort comes from and we know where in the specification document the requirements for this were hidden. The customer might then say: "Let us talk about this feature, i don't want to spend so much time on it". We can then look into the requirements list for this feature and check what the biggest points are and if we can reduce effort here.

6. During this discussion, we add another 2 Columns to our excel sheet: New Estimation and New Comment. After (or better: during) the discussion with the customer, we fill in the newly estimated person days and the comment, what was changed towards the old estimation in these columns. Then we define another Column in the Pivot Table that aggregates this new estimations per Feature for us.

7. Finally we write down the features along with the references to the specification document, the new estimated time and the new comments (if any) in a technical specification document, add some design and architecture information and we have our offer.

We tried quite a lot of approaches in projects of different sizes but this seemed to be the best way so far for us to deal with big specification documents the PHP way. Maybe someday if i have a lot of time, i will write a database driven PHP app replacing the Excel sheet. But so far, it works great this way