Software development is a young profession, and we are still learning the techniques and building the tools to do it effectively. I've been involved in this activity for over three decades and in the last two I've been writing on this website about patterns and practices that make it easier to build useful software. The site began as a place to put my own writing, but I also use it to publish articles by my colleagues.

In 2000, I joined ThoughtWorks, where my role is to learn about the techniques that we've learned to deliver software for our clients, and pass these techniques on to the wider software industry. As this site has developed into a respected platform on software development, I've edited and published articles by my colleagues, both ThoughtWorkers and others, to help useful writing reach a wider audience.

photo of Martin Fowler

photo: Christopher Ferguson

Martin Fowler

A website on building software effectively

If there's a theme that runs through my work and writing on this site, it's the interplay between the shift towards agile thinking and the technical patterns and practices that make agile software development practical. While specifics of technology change rapidly in our profession, fundamental practices and patterns are more stable. So writing about these allows me to have articles on this site that are several years old but still as relevant as when they were written.

As software becomes more critical to modern business, software needs to be able to react quickly to changes, allowing new features to be be conceived, developed and put into production rapidly. The techniques of agile software development began in the 1990s and became steadily more popular in the last decade. They focus on a flexible approach to planning, which allows software products to change direction as the users' needs change and as product managers learn more about how to make their users effective. While widely accepted now, agile approaches are not easy, requiring significant skills for a team, but more importantly a culture of open collaboration both within the team and with a team's partners.

This need to respond fluently to changes has an important impact upon the architecture of a software system. The software needs to be built in such a way that it is able to adapt to unexpected changes in features. One of the most important ways to do this is to write clear code, making it easy to understand what the program is supposed to do. This code should be divided into modules which allow developers to understand only the parts of the system they need to make a change. This production code should be supported with automated tests that can detect any errors made when making a change while providing examples of how internal structures are used. Large and complex software efforts may find the microservices architectural style helps teams deploy software with less entangling dependencies.

Creating software that has a good architecture isn't something that can be done first time. Like good prose, it needs regular revisions and programmers learn more about what the product needs to do and how best to design the product to achieve its goals. Refactoring is an essential technique to allow a program to be changed safely. It consists of making small changes that don't alter the observable behavior of the software. By combining lots of small changes, developers can revise the software's structure supporting significant modifications that weren't planned when the system was first conceived.

Software that runs only on a developer's machine isn't providing value to the customers of the software. Traditionally releasing software has been a long and complicated process, one that hinders the need to evolve software quickly. Continuous Delivery uses automation and collaborative workflows to remove this bottleneck, allowing teams to release software as often as the customers demand. For Continuous Delivery to be possible, we need to build in a solid foundation of Testing, with a range of automated tests that can give us confidence that our changes haven't introduced any bugs. This leads us to integrate testing into programming, which can act to improve our architecture.

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Melrose, MA (2020)

Data Management

There are many kinds of software out there, the kind I'm primarily engaged is Enterprise Applications. One of the enduring problems we need to tackle in this world is data management. The aspects of data managment I've focused on here are how to migrate data stores as their applications respond to changing needs, coping with different contexts across a large enterprise, the role of NoSQL databases, and the broader issues of coping with data that is both Big and Messy.

Domain-Specific Languages

A common problem in complex software systems is how to capture complicated domain logic in a way that programmers can both easily manipulate and also easily communicate to domain experts. Domain-Specific Languages (DSLs) create a custom language for a particular problem, either with custom parsers or by conventions within a host language.

Books

I've written seven books on software development, including Refactoring, Patterns of Enterprise Application Architecture, and UML Distilled. I'm also the editor of a signature series for Addison-Wesley that includes five jolt award winners.

My Books Page...

Conference Talks

I'm often asked to give talks at conferences, from which I've inferred that I'm a pretty good speaker - which is ironic since I really hate giving talks. You can form your own opinion of my talks by watching videos of some my conference talks.

My Videos Page...

Board Games

I've long been a fan of board games, I enjoy a game that fully occupies my mind, clearing out all the serious thoughts for a bit, while enjoying the company of good friends. Modern board games saw dramatic improvement in the 1990's with the rise of Eurogames, and I expect many people would be surprised if they haven't tried any of this new generation. I also appear regularly on Heavy Cardboard.

My Board Games page...

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The Lies that can Undermine Democracy

Tue 12 Jan 2021 09:56 EST

Like many Americans, I was transfixed and horrified by the recent assault on the Capitol. Much of this anger originates in lies perpetrated by irresponsible politicians and spread through media agencies. Lies like this can destroy democracies, and while we must have free speech we must not be free of the consequences of that speech

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Distributed Systems Pattern: Consistent Core

Tue 05 Jan 2021 09:43 EST

Unmesh has a few more of his Patterns of Distributed Systems ready to share with the world. In this one he looks at the problem of a large cluster, one that is too large to effectively maintain strong consistency, yet needs to maintain some data in a strongly consistent way. It can do this by using a smaller cluster, which he calls a Consistent Core.

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Maximizing Developer Effectiveness

Tue 05 Jan 2021 09:40 EST

My colleague Tim Cochran has helped many software engineering organizations transform to respond faster to changing market needs. Often companies struggle with these transformations and a primary reason for these problems is that engineering organization has neglected to provide developers with an effective working environment. The key to to developing an effective environment is to concentrate on feedback loops.

In this first installment, Tim contrasts a developer's day between high-effectiveness and low-effectiveness environments, using this contrast to show that poor organizations need to remove the common frictions that make developers feel unproductive .

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My favorite musical discoveries of 2020

Tue 22 Dec 2020 12:56 EST

Like most people, I'm looking forward to seeing 2020 in the rear-view mirror, but even this ugly year has brought some good things. For the last three decades I've regularly bought a few albums every month, and I thought I'd pick out a half-dozen favorites in the hope that they lead some readers to share at least a bit of my musical tastes. I've been doing most of my musical buying on Bandcamp, so you can easily sample them.

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Data Mesh Principles and Logical Architecture

Thu 03 Dec 2020 10:27 EST

Last year, my colleague Zhamak Dehghani introduced the notion of the Data Mesh, shifting from the notion of a centralized data lake to a distributed vision of data. Based on more thinking, and the lessons of a year's worth working with clients, she's now written an article outlining four foundational principles of a data mesh, and how they drive a logical architecture.

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Don't put data science notebooks into production

Wed 18 Nov 2020 10:25 EST

We've come across many clients who are interested in taking the computational notebooks developed by their data scientists, and putting them directly into the codebase of production applications. My colleague David Johnston points out that while data science ideas do need to move out of notebooks and into production, trying to deploy that notebooks as a code artifact breaks a multitude of good software practices. Predictably, that results in a number of observed pain points. This behavior is a symptom of a deeper problem: a lack of collaboration between data scientists and software developers.

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