Introduction to Agile Concepts in Real-Time and Embedded Systems Development
Different people mean different things when they use the term agile. The term was first used to describe a lightweight approach to performing project development after the original term, Extreme Programming (XP),1 failed to inspire legions of managers entrusted to oversee development projects. Basically, agile refers to a loosely integrated set of principles and practices focused on getting the software development job done in an economical and efficient fashion.
This chapter begins by considering why we need agile approaches to software development and then discusses agile in the context of real-time and embedded systems. It then turns to the advantages of agile development processes as compared to more traditional approaches.
The Agile Manifesto
A good place to start to understand agile methods is with the agile manifesto.2 The manifesto is a public declaration of intent by the Agile Alliance, consisting of 17 signatories including Kent Beck, Martin Fowler, Ron Jeffries, Robert Martin, and others. Originally drafted in 2001, this manifesto is summed up in four key priorities:
- Individuals and interactions over processes and tools
- Working software over comprehensive documentation
- Customer collaboration over contract negotiation
- Responding to change over following a plan
To support these statements, they give a set of 12 principles. I’ll state them here to set the context of the following discussion:
- Our highest priority is to satisfy the customer through early and continuous delivery of valuable software.
- Welcome changing requirements, even late in development. Agile processes harness change for the customer’s competitive advantage.
- Deliver working software frequently, from a couple of weeks to a couple of months, with a preference to the shorter timescale.
- Business people and developers must work together daily throughout the project.
- Build projects around motivated individuals. Give them the environment and support they need, and trust them to get the job done.
- The most efficient and effective method of conveying information to and within a development team is face-to-face conversation.
- Working software is the primary measure of progress.
- Agile processes promote sustainable development. The sponsors, developers, and users should be able to maintain a constant pace indefinitely.
- Continuous attention to technical excellence and good design enhances agility.
- Simplicity—the art of maximizing the amount of work not done—is essential.
- The best architectures, requirements, and designs emerge from self-organizing teams.
- At regular intervals, the team reflects on how to become more effective, then tunes and adjusts its behavior accordingly.
Agile methods have their roots in the XP (Extreme Programming3) movement based largely on the work of Kent Beck and Ward Cunningham. Both agile and XP have been mostly concerned with IT systems and are heavily code-based. In this book, I will focus on how to effectively harness the manifesto’s statements and principles in a different vertical market—namely, real-time and embedded—and how to combine them with modeling to gain the synergistic benefits of model-driven development (MDD) approaches.4