Agile Principles

Relevance’s Perspective on Agile Methods

"Agile" means many different things to different people. At Relevance, there are two primary lenses through which we view and understand agile methods: the Agile Manifesto, and the concept of nested feedback loops. This page explains how we work as seen through those two lenses.

Interpreting the Agile Manifesto

The Agile Manifesto provides very broad guidelines:

We are uncovering better ways of developing software by doing it and helping others do it. Through this work we have come to value:

  • Individuals and interactions over processes and tools
  • Working software over comprehensive documentation
  • Customer collaboration over contract negotiation
  • Responding to change over following a plan

That is, while there is value in the items on the right, we value the items on the left more.

Agile Manifesto »

First of all, don’t stop reading after the list! The things on the right do have value. The manifesto is about what gets priority, not what gets done.

That said, here’s how we put these guidelines into practice:

Individuals and Interactions

No matter what the problem is, it's always a people problem.

—Gerald M. Weinberg in Secrets of Consulting

The first principle of the Agile Manifesto is to value individuals and interactions over processes and tools.

As software developers, we are actually passionate about tools. And we love our processes as well. Both processes and tools help us get things done.

But tools and processes can get in the way of people and relationships. This principle guides us in choosing tools. We choose tools that amplify the individual’s effectiveness, rather than tools that the person has to steer and control. And we choose tools that facilitate collaboration and communication. Here is a short list of examples:

  • Ruby and Clojure, our preferred programming languages, have a lot of power and allow programmers to be expressive and clear, without a lot of ceremony that must be observed.
  • Rails, our preferred web development platform, solves the most common and well-understood problems of web development for us, but gets out of our way when we need to do something unusual.
  • The Git source control system (along with GitHub, the Git-based central repository we use) is designed to facilitate collaboration and experimentation. It also makes switching between tasks very fast and cheap.
  • RSpec allows us to write clean, expressive executable tests that serve as documentation of how the code should work.
  • Our office workspace is designed around pairing stations. They allow two programmers to work together easily on the same problem.
  • In addition to tools, we choose processes that emphasize people and communication. Pair programming is a part of that, and so is the daily standup meeting. We have retrospectives to talk about what went well and what could be improved (and usually people, not tools, are at the core of both of those topics).
Working Software

The second principle of the Agile Manifesto is to value working software over comprehensive documentation.

At Relevance, we keep software working and ready to ship throughout the development lifecycle by:

It's also important to discuss documentation. Historically, in software development, it's been a priority to exhaustively document everything: requirements, design, test suites, correct usage, and so on. But that's expensive; so expensive that often the software itself suffers from the effort devoted to documentation. So we don't write documentation just because; we write documentation when it has value. (And we work with our customers to decide whether it's valuable to them.) Also, we try to write documentation that pays for itself in more than one way.

Occasionally, our customers will want traditional documentation: prose descriptions of architecture, design, or correct usage, with diagrams. We'll happily do that! It becomes a task which is scheduled along with the development tasks, and its priority (as with all tasks) is determined by the customer.

More often, though, that kind of documentation just isn’t a high priority. There are two kinds of documentation that are always really important, though. They are:

  • documentation that helps users understand how to use the software
  • documentation that helps future programmers (maybe even us!) understand how to fix, maintain, and extend the software.

These days, the first problem is usually tackled simply by making the system more usable. When is the last time you read a user manual for a piece of software?

The second problem we solve through tests—executable specifications for how the system (in whole or in part) should work. The tools we use allow us to write specs that read like design documentation to skilled programmers, and some of our specs can be understood and verified by our customers. Both of these techniques have two important advantages over traditional design documentation. First, because they can be used to find errors in the system, they don't cost any extra; they're a part of the development and QA processes. Second, as long as we insist that those test all run successfully (via CI, we know that they aren’t out of date—they still reflect the way the code actually works.

Customer Collaboration

The third principle of the Agile Manifesto, valuing "customer collaboration over contract negotiation"", can seem self-serving when it's a vendor saying the words. But of course, as many customers have learned, contracts can be exploited by both sides, as both shields and weapons. (We've heard other developers say, "They're going to hate it, but we're giving them exactly what the contract specifies.")

Contracts are important and useful, and time spent negotiating them can be well spent. But when that gets in the way of effective collaboration, it's a bad trade. Customer/vendor relationships are much better when the two are working together as partners, and when the sense of safety is built into the way you work.

Here's just one example out of many: One of the many reasons we like to work in iterations is that we can deliver working software to the customer every other week. That means if there's some external reason (like a sudden budget crunch) that they need to cut the project short, they will have still received something valuable from the relationship. And we like to educate our customers about our standards (this website is part of that effort) so that they can see how we work, and hold us to our promises if necessary. GitHub allows our customers to look at the code if they are interested, and especially the specs. Jenkins allows them to watch our test suite grow, and see that we are keeping the tests passing.

Responding to Change

The fourth principle of the Agile Manifesto is to value responding to change over following a plan.

At Relevance, the following practices help teams respond quickly to change:

The principle doesn't devalue planning—just sticking to the plan. Planning is valuable in itself, and because the plan helps us recognize when things have changed; it helps us understand the implications of change, how we need to adjust, and the likely cost. The important thing is that, as we make plans, we understand that the plan may have to change. Planning is an ongoing time-boxed activity that includes

Nested Feedback Loops

We believe that software projects are dominated by change: changing requirements, changing environments, changing interactions with other systems, and changing user communities.

Glenn Vanderburg's paper, Extreme Programming Annealed , explains the structure and workings of agile methods in terms of nested, time- and scale-defined feedback loops. We think that's a great way to understand how agile processes work, and how to tailor them to particular situations.

In order to respond quickly to change, our process includes the following feedback loops. These feedback loops operate on different time scales to facilitate everything from tiny adjustments to wholesale changes in a project's direction.

Feedback Loop
15 minutes
1-2 hours
Every other iteration
1-2 hours
Every other iteration
1-2 hours