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 as 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.

Photostream

Cape Cod, MA (2017)

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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Recent Changes

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Bliki: Periodic Face-to-Face

Tue 27 Feb 2024 09:17 EST

Improvements in communications technology have led an increasing number of teams that work in a Remote-First style, a trend that was boosted by the forced isolation of Covid-19 pandemic. But a team that operates remotely still benefits from face-to-face gatherings, and should do them every few months.

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Improving my Emacs experience with completion

Thu 25 Jan 2024 13:20 EST

I’ve been using Emacs for many years, using it for any writing for my website, writing my books, and most of my programming. (Exceptions have been IntellJ IDEA for Java and RStudio for R.) As such I’ve been happy to see a lot of activity in the last few years to improve Emacs’s capabilities, making it feel rather less than a evolutionary dead end. One of the biggest improvements to my Emacs experience is using regexs for completion lists.

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Bottlenecks of Scaleups #06: Onboarding

Tue 23 Jan 2024 09:13 EST

The last year has been a hard one for the technology industry, which faced its greatest waves of cutbacks and layoffs since the dotcom crash at the beginning of the century. As 2024 begins, we're seeing the early signs of a turn-around, which hopefully means technology organizations will soon be thinking of hiring again. Should such happy days return, firms will again run into the common problem of taking too long for new hires to become effective. Tim Cochran and Premanand Chandrasekaran address this in the sixth part of our series on the bottlenecks of scaleups. In this first installment, Tim and Prem look the signs that a growing organization is running into this bottleneck.

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A major revision of Continuous Integration

Thu 18 Jan 2024 10:01 EST

At the turn of the century, I was lucky to involved in several projects that developed the practice of Continuous Integration. I wrote up our lessons from this work in article on my website, where it continues to be a oft-referenced resource for this important practice. Late last year a colleague contacted me to say that the article, now nearly twenty years old, was still useful, but was showing its age. He sent me some suggested revisions, and I used this as a trigger to do a thorough revision of the article, considering every section in the original, and adding new ones to deal with issues that have appeared in the last two decades.

During those decades Feature Branching has been widely adopted in the industry. Many colleagues of mine feel that Continuous Integration is a better fit for many teams, I hope this article will help readers assess if this is the case, and if so, how to implement Continuous Integration effectively.

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Bliki: Legacy Seam

Thu 04 Jan 2024 09:13 EST

When working with a legacy system it is valuable to identify and create seams: places where we can alter the behavior of the system without editing source code. Once we've found a seam, we can use it to break dependencies to simplify testing, insert probes to gain observability, and redirect program flow to new modules as part of legacy displacement.

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