IBM SG24-7368-00 manual Two analogies, Project management

Two analogies

Consider two analogies here: Project management and restaurant ownership.

Project management

If you are a project manager, you want to complete your project on schedule and within budget. You have a set of people who will carry out a set of tasks. Your job is to schedule the tasks, assign them to workers, and ensure that the project remains on schedule and finishes within budget. Now consider a system to be a project—not the task of building the system, but the system itself. There is a set of tasks that you want the system to perform, you must distribute those tasks to a set of resources, and you want the tasks to be accomplished within a certain schedule, budget, and other constraints. Reasoning about this distribution problem is a core pillar of MDSD.

Restaurant ownership

Now imagine that you want to start a restaurant. Your goals might be varied and personal, but one of them better be to make a profit. There will be many aspects involved in making a profit, but one of them will be to maximize your throughput—that is, to serve as many quality meals as possible to as many customers as possible. You have many options at your disposal to accomplish this. Each option has a cost associated with it. You have to balance costs with the return inherent in each option.

You might start with a short-order cook in front of a stove, behind a counter with stools for the customers. Your rent is low, because you need very little space. Your salaries are low, because you only have to hire a cook or two. But the cook has to invite the customer to sit down, then take the order, cook it, deliver it, and wash dishes. You soon discover that your one employee can only handle a small number of customers at one time, because he or she has to do virtually everything. Your cook is very good, so word gets around. People come to the diner in droves, but soon get frustrated because of the long wait and lack of seating. Your cook gets burnt out, because he or she has to be constantly on the go. The throughput of your restaurant is limited, as are its profits.

You could add tables and some wait staff. Your rent has gone up because your space has increased, as have your salaries because your staff is increased, but you can increase the output of the cook because he or she can focus on the cooking, and the throughput of the restaurant through the division of responsibilities. Still, you will likely be constrained by the capabilities of the wait staff. Now they have to greet the customers, seat them, take their orders, bring them to the kitchen, retrieve the orders, carry them to the tables, give the customers their bills, collect the money, clear the table, and set it again for the next customers. Customers are frustrated because it takes so long to get seated, get their meals, and get their checks. You risk losing customers. So you add staff to clear and set the tables.

Chapter 1. Introduction 7