Martin Fowler

Partner with the AI, throw away the code

2025-07-31T10:16:00-04:00

Matteo Vaccari shows why the common metric of AI code acceptance has big hole. An LLM can be helpful even if you throw away its code.

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Who is LLM

2025-07-22T13:38:00+05:30

It's become a common habit for developers to give Large Language Models (LLMs) a persona when working with them. I describe four of them, a stubborn donkey, a genie, a slot machine, and Uriah Heep.

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Generative AI in software and essaying

2025-07-21T14:58:00-04:00

Korny Sietsma has a great example of how using an LLM for coding is very helpful but with limitations…

and a thoughtful general essay on why the hype and the immovable skeptics are both missing the train.

While here, a professor of poetry ponders (gift link) on the value and limits of AI with writing:

One of the real challenges here is the way that A.I. undermines the human value of attention, and the individuality that flows from that.

What we stand to lose is not just a skill but a mode of being: the pleasure of invention, the felt life of the mind at work.

Three worthwhile articles yesterday

2025-07-10T10:58:00-04:00

Three articles I enjoyed yesterday:

Stephen O’Grady talks about how Gen AI tools break two common constants with developer tools: they are willing to flit between Gen AI tools and they are willing to pay for them. This implies that it’s not too late for new tools to appear, and that enterprise adoption will be slowed by a lack of consensus on which direction to go.

Pete Hodgson continues his excellent writing on Gen AI by proposing an approach to leading engineers towards an AI-assisted future, centered around a the concept of aligned autonomy. He advocates an explicit experimentation phase, followed by supporting adoption and measuring their impact.

Charity Majors reflects on her career. I really resonated with her words: “I think I’m less interested in my own happiness (whatever that means) than I am interested in doing work that feels worth doing.”

I still care about the code

2025-07-09T10:33:00-04:00

Even with LLMs, Birgitta Böckeler still cares about the code: “LLMs are NOT compilers, interpreters, transpilers or assemblers of natural language, they are inferrers.

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Why Organizations Need Expert Generalists

2025-07-02T10:05:00-04:00

In complex environments, the characteristics of Expert Generalists lead Gitanjali, and I thus complete our article by summarizing the value of them to be particularly valuable in driving tasks to completion. Unmesh, this skill.

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Expert Generalists need specialists (and LLMs)

2025-07-01T09:17:00-04:00

While we've spent this article praising the Expert Generalist, Unmesh, Gitanjali, and I simultaneously do not deny the value of specialist knowledge. To be the most efficient, a team needs some specialist skill. We've also observed that Expert Generalist capabilities are considerably more valuable when working with LLMs.

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Growing Expert Generalists

2025-06-25T08:48:00-04:00

To grow Expert Generalists we need to focus attention on fundamentals rather tools. As an example, Unmesh, Gitanjali, and I describe a workshop we've used to break silos of application development, data engineering, and devops

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LLMs bring new nature of abstraction

2025-06-24T10:02:00-04:00

Like most loudmouths in this field, I’ve been paying a lot of attention to the role that generative AI systems may play in software development. I think the appearance of LLMs will change software development to a similar degree as the change from assembler to the first high-level programming languages. The further development of languages and frameworks increased our abstraction level and productivity, but didn’t have that kind of impact on the nature of programming. LLMs are making that degree of impact, but with the distinction that it isn't just raising the level of abstraction, but also forcing us to consider what it means to program with non-deterministic tools.

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Assessing Expert Generalists

2025-06-24T09:45:00-04:00

We have two crucial checkpoints for spotting — and then nurturing — expert generalists. Unmesh, Gitanjali, and I look at hiring and career progression.

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Expert Generalists: three more characteristics

2025-06-19T08:48:00-04:00

Unmesh, Gitanjali, and I finish our list of characteristics of an Expert Generalist by describing how these folks favor fundamental knowledge in a domain, possess a blend of broad and deep skills, and know how to build a rough, perceptive sense - a sympathy - for related domains.

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Expert Generalists: first three characteristics

2025-06-18T09:13:00-04:00

As computer systems get more sophisticated we've seen a growing trend to value deep specialists. But we've found that our most effective colleagues have a skill that comes from spanning many specialties. We are thus starting to explicitly recognize this as a first-class skill of “Expert Generalist”. This is the first installment of an article detailing how we think about this skill, starting with the first three characteristics of an Expert Generalist.

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Autonomous coding agents: A Codex example

2025-06-04T09:50:00-04:00

In the past few weeks, multiple “autonomous background coding agents” have been released. Birgitta Böckeler tried out giving a task to OpenAI Codex to see what she could learn. Here she describes one particular Codex run, to help us look behind the scenes, and make some observations about its contribution to our work.

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Should I still use analytics?

2025-06-03T09:23:00-04:00

I set up Google Analytics on my site in 2010, and since then use it to track page views to my site. I only care about page views, which I find useful to figure out which pages get the most traffic. It’s interesting data, and sometimes rather useful. But Google collects much more information than just page views, and it’s tracking is more intrusive than I would like. But I had other things I’d rather spend to spend my time on, so doing anything about it never made it high enough up my todo list.

But last month I finally did something, having come across some information that did I thought did what I wanted. Essentially I want things set up so that I don’t need to bother with a cookie banner because I only track things that are trackable when someone says “deny all”. Based on some google documentation, I changed my google analytics fragment to:

<script async src="https://www.googletagmanager.com/gtag/js?id=G-6D51F4BDVF"></script>
<script>
  window.dataLayer = window.dataLayer || [];
  function gtag(){dataLayer.push(arguments);}
  gtag('consent', 'default', {
    'ad_user_data': 'denied',
    'ad_personalization': 'denied',
    'ad_storage': 'denied',
    'analytics_storage': 'denied',
    'wait_for_update': 500,
  });
  gtag('js', new Date());

  gtag('config', 'G-6D51F4BDVF');
</script>

As I understand the documentation, this should turn off the most problematic tracking, but still send a page view event. I took a look at it the following day, and everything seemed to be ok, but now, a couple of weeks later, page views reported by Google Analytics have dropped drastically. Not to zero, but to near zero.

I’ve spent a bit of time trying to figure out what’s happening. I used google tag assistant and it indicates the page view events are being sent correctly. But that doesn’t explain why I’m not seeing the page views in my Google data.

I’m not sure what to do next. I don’t want to spend too much time on this, after all I’d rather work on writing and editing. I did consider other services to do the tracking, but it looks we’re talking about $100s a month - and it’s just not worth that much to me. There are open source setups I could try an configure on my server, but again that’s effort I don’t really want to go into. Maybe I just live without analytics data.

Bliki: Say Your Writing

2025-05-28T09:50:00-04:00

Here's one of the best tips I know for writers, which was told to me by Bruce Eckel.

Once you've got a reasonable draft, read it out loud. By doing this you'll find bits that don't sound right, and need to fix. Interestingly, you don't actually have to vocalize (thus making a noise) but your lips have to move. ¹

This advice is for those who, like me, strive to get a conversational tone to their writings. A lot of people are taught to write in a different way than they speak, but I find prose much more engaging with this conversational tone. I imagine I'm sitting in pub, explaining the concepts to my companions. I've heard people say that when reading my work, they can hear me speaking it - which is exactly the effect I'm after.

Too often I read prose that feels flabby. Two kinds of flab stand out: corporate prose and academic prose. I often tell people that if they read their prose and it sounds like it could have come from Accenture ² , then they are doing it wrong. And, of course, the passive voice is rarely preferred. Speaking makes this flab noticeable, so we can cut it out.

In my case I find I constantly (silently) speak the words as I'm writing.

Notes

1: I suspect what matters here is that you need to trigger the part of your brain that processes spoken word as opposed to written word - and that part is sensitive to blandness.

2: I pick on Accenture since they are a big consulting company, and thus do all the things needed to sound blandly corporate. The worst case I ran into was many years ago when some sparkling prose by a colleague of mine was turned by editors at Microsoft into a tasteless pudding. There is a perceptible corporate way of writing, often learned subconsciously, that is rife and ruinous.

Interviewed by James Lewis at goto Copenhagen

2025-05-23T13:48:00-04:00

At goto copenhagen last year, my friend James Lewis interviewed me and Goto have just released the video. I talk about when I learned about iterative design from Kent Beck, the dangers of product owners interfering with business-developer communication, and writing the agile manifesto. During this he specifically asked about my essay Is Design Dead. There's also a some audience questions asking if pair programming is a bad thing for introverts like us (no), and (inevitably) the role of LLMs for programmers today.

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Refresh of Agile Threat Modeling

2025-05-20T09:20:00-04:00

Threat modeling is a systems engineering practice where teams examine how data flows through systems to identify what can go wrong - a deceptively simple act that reveals security risks that automated tools cannot anticipate. Often this is done by security analysts as a separate or upfront activity, but Jim Gumbley wrote an article in 2020 explaining how it could be done by teams through small and regular work.

Now Gayathri Mohan has joined Jim to rewrite the article, incorporating what both have them learned about doing and teaching this practice in the last few years. In particular they have extended their approach to perform threat modeling with platform teams.

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Building Custom Tooling with LLMs

2025-05-14T10:10:00-04:00

Tools that treat diagrams as code, such as PlantUML, are invaluable for communicating complex system behavior. But Unmesh Joshi often wished for an extension to walk through these diagrams step-by-step. Yet, extending established tools like PlantUML often involves significant initial setup - parsing hooks, build scripts, viewer code, packaging - enough “plumbing” to deter rapid prototyping.

He narrates now he used an LLM to build a small extension adding step-wise playback to PlantUML sequence diagrams. This illustrates how syntax design, parsing, SVG generation, build automation, and an HTML viewer were iteratively developed through a conversation with an LLM - turning tedious tasks into manageable steps.

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Coding Assistants Threaten the Software Supply Chain

2025-05-13T09:11:00-04:00

We have long recognized that developer environments represent a weak point in the software supply chain. Jim Gumbley and Lilly Ryan explore how agentic coding assistants expand the attack surface of software supply chains and what measures we need to do to safeguard security when using them.

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Function calling using LLMs

2025-05-06T09:02:00-04:00

While LLMs excel at generating cogent text based on their training data, they may also need to interact with external systems. Kiran Prakash describes how we get them to construct external function calls to do this. The LLM does not execute these calls directly, instead it creates a data structure that describes the call, passing that to a separate program for execution and further processing. The LLM's prompt includes details about possible function calls and when they should be used.

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Building TMT Mirror Visualization with LLM

2025-04-30T09:54:00-04:00

Creating a user interface that visualizes a real-world structure — like the Thirty Meter Telescope's mirror — might seem like a task that demands deep knowledge of geometry, D3.js, and SVG graphics. But with a Large Language Model (LLM) like Claude or ChatGPT, you don't need to know everything upfront. Unmesh Joshi describes how working with an LLM gave him a working prototype even when he's unfamiliar with the underlying tech.

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Additional explanatory material for the Deepseek Overview

2025-04-21T09:07:00-04:00

A couple of months ago, my colleague Shayan Mohanty published a technical overview of the series of papers describing the deepseek AI models. He's now gone through that article, adding more explanations to make it more digestible for those of us who don't have a background in building these kinds of models.

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Guiding an LLM for Robust Java ByteBuffer Code

2025-04-17T09:39:00-04:00

AI editors like Cursor can generate code with remarkable speed using LLMs, handling boilerplate and providing functional snippets for various tasks. However, when building robust systems, functional correctness is only the starting point. Code must also be safe, predictable, maintainable, and free from subtle side effects. Unmesh Joshi demonstrates, through a dialogue between a developer and an LLM, how expert guidance is crucial to transform an initial, potentially unsafe code snippet into a robust, system-ready component.

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Updating yesterday's post on social media engagement

2025-04-04T14:32:00-04:00

Some people asked about how many people clicked through the links on these social media posts. I've added some more to the article, partly to explain why I don't have that information, and partly to show overall source data for traffic to the site.

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Social Media Engagement in Early 2025

2025-04-03T09:41:00-04:00

A few years ago, whenever I published a new article here, I would just announce it on Twitter, but since the Muskover its importance has declined, and now I post updates to several services. To compare engagement on these services, I've looked at reposts, likes, and replies to two dozen of my recent posts.

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I've been kidnapped by Robert Caro

2025-04-01T17:22:00-04:00

I've always enjoyed reading, and for most of my life I've particularly enjoyed reading history. I've head many great things about Robert Caro's books, but was deterred by their size. Finally, with his first book newly available as an ebook, I decided to dip my toes in. The books are too good for me to escape.

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The role of developer skills in agentic coding

2025-03-25T10:39:00-04:00

As agentic coding assistants get more capable, Birgitta Böckeler is trying them to change existing codebases. This has led to some impressive collaboration sessions, but she's needed to intervene, correct and steer all the time. In her latest post, she describes examples of these interventions, giving ideas of the types of skills we currently need to correct the tools' missteps.

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Commenting on removing "X" on US passports

2025-02-26T11:49:00-05:00

The new US administration has decided to eliminate the “X” option for gender/sex on passports. I have several non-binary friends, and I don’t see why they should have to select an option that makes no sense for them. I also don’t see how an “X” option on identity documents causes a material problem for anyone else. There’s not much I can do to object to this change, but one little thing is to add a comment on the Federal Register for such rule changes. There are three such pages:

DS-11 new passport application: (deadline 3/17/25) https://www.federalregister.gov/documents/2025/02/14/2025-02648/30-day-notice-of-proposed-information-collection-application-for-a-us-passport

DS-82 passport renewal: (deadline 3/20/25) https://www.federalregister.gov/documents/2025/02/18/2025-02697/30-day-notice-of-proposed-information-collection-us-passport-renewal-application-for-eligible

DS-5504 name change or data corrections: (deadline 3/20/25) https://www.federalregister.gov/documents/2025/02/18/2025-02696/30-day-notice-of-proposed-information-collection-application-for-a-us-passport-for-eligible

It didn’t take me more than a few minutes to make a brief comment (essentially the first three sentences of this post) on all three. Pretty inconsequential compared to the problems facing my non-binary friends.

GenAI Patterns: Fine Tuning

2025-02-25T07:20:00-05:00

While RAG is the most common way to focus a foundation model on material outside its training set, Bharani Subramaniam and I now finish our current batch of patterns by examining our experience with Fine Tuning where we learned to prioritize curating high-quality data.

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GenAI Patterns: Guardrails and RAG overview

2025-02-19T07:02:00+07:00

Gen AI systems are gullible, and can easily be tricked into responding in ways that are contrary to an enterprise's policies or leak confidential information. Bharani Subramaniam and I describe how we can counter this by adding guardrails at the boundaries of the request/response flow. We also conclude our discussion of RAG with an overview of how all the RAG component patterns fit together.

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