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Methods Need Theory


Your Current Method: A Cocktail of Practices

The method you are using for your development -- commercial or locally developed, new or old, known or obscure -- is really just a combination of elements from the methodology literature, spiced up with some domain- or business-specific extensions. The basic ingredients are individual practices.

If we separate the ingredients from the cocktail we can empower people to build the methods they need; such methods, being devised in a modular fashion, will be able to evolve quickly as a result of lessons learned and in response to the demands of a quickly changing industry.

Developing a Theory

The economic pressure is such that current characteristics, -- the fashion-industry-like versatility, the politics-like use of propaganda -- will not completely go away. But methodologists who are concerned about the viability of software engineering should bring reason to the discipline and work in a different way.

What we are missing is the cornerstone of science and engineering: a theory, and its validation. Here are the steps that we can take to turn software methodology into a serious endeavor.

1. Model the Nature of Methods. Software development is a human activity, but it consists of well-defined steps with well-understood relations between them. At least the definition and understanding exist implicitly, in the minds of experienced professionals. This is not enough; we need a strong theory of software development. Formal methods give us the right tools to perform this modeling; object-oriented languages with contracts can also serve that purpose. Without a precise, unambiguous model of the tasks and constraints of software development we cannot improve things significantly. The model should be method-independent (describing the problem, not the solution); and it should not only include definitions and axioms but -- the part too often missing in formal models -- theorems stating fundamental properties of all systems and all viable methods.

2. Find the Kernel -- the Mother of all Methods. All methods, beyond the hyped differences, share many properties. Using the theory as a basis, we should describe the properties that any method should satisfy if it is going to be effective for developing quality software. After all, they are all used to develop software, and they all acknowledge that there are certain things that we always need to do when we develop software. We always write code, we always test it in some way, we always think about requirements (documented or not), we always have a backlog (explicit or implicit), and we always have a plan on a paper or in our heads. Using the theory as a basis, we should describe the properties that any method should satisfy if it is going to be effective for developing quality software.

We need to find the "essential core" or "kernel" of software development, which cannot be made simpler. For example, by studying about 50 methods, including XP and Scrum, we have identified a kernel with some 15+ elements, things we always do or always produce.

3. Describe Each Interesting Method Using the Kernel. With the kernel in place, all methods can be described and compared. We can harvest the implicit practices from all widely used and proven methods or processes, such as architecture, components, iterations, scrums, etc. Some practices will overlap, e.g. use-case driven development and feature-driven development. Some practices will complement one another, e.g. use-case driven development and design-by-contract.

The kernel clears away the cosmetic differences between methods, such as the same thing being called by different names in different methods. For example RUP talks about iterations whereas Scrum talks about sprints, but they mean pretty much the same thing. By doing this we can clearly see the real differences between different methods.

Since the kernel is agnostic in relation to any specific practice, we can simply find out what is the actual difference between different practices, not just on the surface but in depth. This decreases the element of religion in which every method is embedded.

Moving On

The above represents a clear call to action which we hope will be adopted (after any suitable adaptations) by all those who agree with us that the software industry needs to reach maturity.

Perhaps the most important step is to realize that what unites the different schools of thought is more important than what separates them. In particular:

  • Agile vs. process: the differences are exaggerated. The goals are the same on both sides: producing excellent software smoothly. All processes need agility, since in software more than anywhere else change is the rule and stability the exception. All agile methods, if applied to enterprise-critical projects, need a process, including specification and design.

  • Formal vs. informal: software practitioners must realize that any form of progress includes a dose of formal methods, and that they have nothing to fear from them. All engineering relies on math: can one imagine an electrical or mechanical engineer refusing to learn and apply mathematical techniques? Formal methods have their limits -- no one claims that they solve everything -- but are far beyond "academic" and have repeatedly proved their value when used appropriately. Whether we realize it or not, they are already pervasive in some areas (type checking as present in modern programming languages is a form of proof, and hardware design is increasingly based on mathematical techniques). As the IT industry moves towards a more professional mode of operation it will increasingly rely on selectively applied mathematical techniques.

Only by ignoring superficial differences and applying all ideas, regardless of their origin, shall we provide the industry with what it is entitled to expect from the experts: scientifically sound, practically useful methods and tools.

These are our views. Are we chasing windmills? Or is it possible to clean up the methodology mess and develop the sound basis that the industry needs? One thing is certain: progress can only result from the collaboration of many people. There are many forums to discuss these issues, starting with our blogs (http://ivarblog.com/ and http://bertrandmeyer.com). Tell what you think, and help software engineering move on to the adult phase.


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