The boss needs a new evaluation based on a new data source. There isn’t time to load the data into an existing data warehouse, let alone into a new one. It seems obvious to reach for “agile” BI tools such as Excel or Power BI. After several months and more “urgent” evaluations, a maintenance nightmare threatens. But there is another way: In this article I introduce the idea of architectural T-shirt sizes, illustrated using our own dashboard. Of course, different requirements lead to different architectural approaches, but at the same time, it should be possible that architecture can grow as a BI system is expanded.
The summer holidays were just over, and I was about to take on a new management function within our company. It was clear to me: I wanted to make my decisions in a data-driven way and to offer my employees this opportunity. From an earlier trial, I already knew how to extract the required data from our SAP system. As a BI expert, I would love to have a data warehouse (DWH) with automated loading processes and all the rest. The problem was that, as a small business, we ourselves had no real BI infrastructure. And alongside attending to ongoing customer projects, my own time was pretty tight. So did the BI project die? Of course not. I just helped myself with the tool I had to hand, in this case Microsoft Power BI. Within a few hours the first dashboard was ready, and it was published in our cloud service even faster.
My problem was solved in the short term. I could make daily-updated data available to my employees. Further requirements followed, so I copied the power BI file and began fitting it in here and there. Over the next few weeks, I added new key figures to it and made more copies. However, I was only partly able to keep the various dashboard copies “in sync”. In addition, operational problems came up. Of course, I had connected the SAP system under my personal username, whose password has to be changed regularly. This in turn led to interruptions to the data updating and required manual effort in reconfiguring the new password in Power BI.
I guess a lot of professional users have been in my shoes. You have to find a solution on the quick – and before you know it, you’re in your own personal maintenance nightmare. At the same time, a fully developed BI solution is a distant prospect, usually for organizational or financial reasons.
As an expert in the adaptation of agile methods for BI projects, I have been dealing with this problem for a long time: How can we both address the short-term needs of the professional user and create the sustainability of a “clean” solution? As a father of two daughters, I remembered
how my children grew up – including the fact that you regularly have to buy bigger clothes. The growth process is continuous, but from time to time we have to get a new dress size. It is exactly this principle that can also be applied to BI solutions and their architecture. Figure 1 shows four example T-shirt sizes, which are explained in more detail below.
This approach corresponds to my first set of dashboards. A BI front-end tool connects directly to a source. All metadata, such as access data for the source systems, business rules, and key figure definitions, are developed and stored directly in the context of the information products created.
This T-shirt size is suitable for a BI project that is still in its infancy. It is often only then that a broader aim is formulated involving everything that you would like to analyze and evaluate – this is when “thinking big” begins. Practically, however, not much more known than the data source. But you would also like to be more explorative and produce first results promptly, so it makes sense to begin with the small and technically undemanding.
However, this approach reaches its limits very quickly.
