Latest Posts (15 found)
Martin Fowler 2 weeks ago

Anchoring AI to a reference application

Service templates are a typical building block in the “golden paths” organisations build for their engineering teams, to make it easy to do the right thing. The templates are supposed to be the role models for all the services in the organisation, always representing the most up to date coding patterns and standards. One of the challenges with service templates though is that once a team instantiated a service with one, it’s tedious to feed template updates back to those services. Birgitta Böckeler considers whether GenAI can help with that.

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Martin Fowler 3 weeks ago

To vibe or not to vibe

Birgitta Böckeler examines the risk assessment around when to use vibe coding, using three dimensions of risk: Probability, Impact, and Detectability

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Martin Fowler 1 months ago

Some thoughts on LLMs and Software Development

I’m about to head away from looking after this site for a few weeks (part vacation, part work stuff). As I contemplate some weeks away from the daily routine, I feel an urge to share some scattered thoughts about the state of LLMs and AI. ❄                ❄                ❄                ❄ I’ve seen a few early surveys on the effect AI is having on software development, is it really speeding folks up, does it improve or wreck code quality? One of the big problems with these surveys is that they aren’t taking into account how people are using the LLMs. From what I can tell the vast majority of LLM usage is fancy auto-complete, often using co-pilot. But those I know who get the most value from LLMs reckon that auto-complete isn’t very useful, preferring approaches that allow the LLM to directly read and edit source code files to carry out tasks. My concern is that surveys that ignore the different work-flows of using LLMs will produce data that’s going to send people down the wrong paths. (Another complication is the varying capabilities of different models.) ❄                ❄                ❄                ❄ I’m often asked, “what is the future of programming?” Should people consider entering software development now? Will LLMs eliminate the need for junior engineers? Should senior engineers get out of the profession before it’s too late? My answer to all these questions is “I haven’t the foggiest”. Furthermore I think anyone who says they know what this future will be is talking from an inappropriate orifice. We are still figuring out how to use LLMs, and it will be some time before we have a decent idea of how to use them well, especially if they gain significant improvements. What I suggest, is that people experiment with them. At the least, read about what others are doing, but pay attention to the details of their workflows. Preferably experiment yourself, and do share your experiences. ❄                ❄               ❇                ❄ I’m also asked: “is AI a bubble”? To which my answer is “OF COURSE IT’S A BUBBLE”. All major technological advances have come with economic bubbles, from canals and railroads to the internet. We know with near 100% certainty that this bubble will pop, causing lots of investments to fizzle to nothing. However what we don’t know is when it will pop, and thus how big the bubble will have grown, generating some real value in the process, before that happens. It could pop next month, or not for a couple of years. We also know that when the bubble pops, many firms will go bust, but not all. When the dot-com bubble burst, it killed pets.com, it killed Webvan… but it did not kill Amazon. ❄                ❄                ❄                ❄ I retired from public speaking a couple of years ago. But while I don’t miss the stress of giving talks, I do miss hanging out with my friends in the industry. So I’m looking forward to catching up with many of them at GOTO Copenhagen . I’ve been involved with the GOTO conference series since the 1990s (when it was called JAOO), and continue to be impressed with how they put together a fascinating program. ✢                ❄                ❄                ❄ My former colleague Rebecca Parsons, has been saying for a long time that hallucinations aren’t a bug of LLMs, they are a feature. Indeed they are the feature. All an LLM does is produce hallucinations, it’s just that we find some of them useful. One of the consequences of this is that we should always consider asking the LLM the same question more than once, perhaps with some variation in the wording. Then we can compare answers, indeed perhaps ask the LLM to compare answers for us. The difference in the answers can be as useful as the answers themselves. Certainly if we ever ask a hallucination engine for a numeric answer, we should ask it at least three times, so we get some sense of the variation. Furthermore we shouldn’t ask an LLM to calculate an answer than we can calculate deterministically (yes, I’ve seen this). It is OK to ask an LLM to generate code to calculate an answer (but still do it more than once). ❄                ❄                ❄                ❄ Other forms of engineering have to take into account the variability of the world. A structural engineer builds in tolerance for all the factors she can’t measure. (I remember being told early in my career that the unique characteristic of digital electronics was that there was no concept of tolerances.) Process engineers consider that humans are executing tasks, and will sometimes be forgetful or careless. Software Engineering is unusual in that it works with deterministic machines. Maybe LLMs mark the point where we join our engineering peers in a world on non-determinism. ❄                ❄                ❄                ❄ I’ve often heard, with decent reason, an LLM compared to a junior colleague. But I find LLMs are quite happy to say “all tests green”, yet when I run them, there are failures. If that was a junior engineer’s behavior, how long would it be before H.R. was involved? ❄                ❄                ❄                ❄ LLMs create a huge increase in the attack surface of software systems. Simon Willison described the The Lethal Trifecta for AI agents: an agent that combines access to your private data, exposure to untrusted content, and a way to externally communicate (“exfiltration”). That “untrusted content” can come in all sorts of ways, ask it to read a web page, and an attacker can easily put instructions on the website in 1pt white-on-white font to trick the gullible LLM to obtain that private data. This is particularly serious when it comes to agents acting in a browser. Read an attacker’s web page, and it could trick the agent to go to your bank account in another tab and “buy you a present” by transferring your balance to the kind attacker. Willison’s view is that “the entire concept of an agentic browser extension is fatally flawed and cannot be built safely”.

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Martin Fowler 1 months ago

From Black Box to Blueprint

A common enterprise problem: crucial legacy systems become “black boxes”—key to operations but opaque and risky to touch. Thiyagu Palanisamy and Chandirasekar Thiagarajan worked with a client to use AI-assisted reverse engineering to reconstruct functional specifications from UI elements, binaries, and data lineage to overcome analysis paralysis. They developed a methodical “multi-lens” approach—starting from visible artifacts, enriching incrementally, triangulating logic, and always preserving lineage. Human validation remains central to ensure accuracy and confidence in extracted functionality. This engagement revealed that turning a system from black box to blueprint empowers modernization decisions and accelerates migration efforts.

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Martin Fowler 1 months ago

Research, Review, Rebuild: Intelligent Modernisation with MCP and Strategic Prompting

The Bahmni open-source hospital management system was began over nine years ago with a front end using AngularJS and an OpenMRS REST API. Rahul Ramesh wished to convert this to use a React + TypeScript front end with an HL7 FHIR API. In exploring how to do this modernization he used a structured prompting workflow of Research, Review, and Rebuild - together with Cline, Claude 3.5 Sonnet, Atlassian MCP server, and a filesystem MCP server. Changing a single control would normally take 3–6 days of manual effort, but with these tools was completed in under an hour at a cost of under $2.

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Martin Fowler 1 months ago

Building your own CLI Coding Agent with Pydantic-AI

CLI coding agents are a fundamentally different tool to chatbots or autocomplete tools - they're agents that can read code, run tests, and update a codebase. Ben O'Mahony explains that while commercial tools are impressive, they don't understand the particular context of our environment and the eccentricities of our specific project. Instead we can build our own coding agent by assembling open source tools, using our specific development standards for: testing, documentation production, code reasoning, and file system operations.

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Martin Fowler 1 months ago

Chatting with Unmesh about building language with LLMs

A few weeks ago, Unmesh Joshi and I started having a conversation about how he likes to grow a language of abstractions when working with an LLM. We thought this was a conversation that others might find interesting so we turned it into an article. We talk about how programming is about both building and applying abstractions and how the LLM helps us in different ways with each activity.

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Martin Fowler 1 months ago

Bliki: Expansion Joints

Back in the days when I did live talks, one of my abilities was to finish on time, even if my talk time was cut at the last moment (perhaps due to the prior speaker running over). The key to my ability to do this was to use Expansion Joints - parts of the talk that I'd pre-planned so I could cover them quickly or slowly depending on how much time I had. The way I'd do this would be to plan for some topics to be optional. The talk would work if I skipped over them, but I could also witter on about them for five (or ten) minutes. Ideally, each of these topics would get one slide, usually with a bunch of key phrases on it - the headings of what I'd talk about should I be talking about it. When I got to the slide, I'd look at how time was going with the talk. If (as was usually the case) I was running short of time, I could cover the slide in about thirty seconds, saying something like: “in doing this, there's a bunch of things you need to consider, but they are out of scope for today's talk”. If, however, I did have time, I could then spend some time talking about them. The slide would be simple, and not provide much of a Visual Channel , but that wasn't so important, after all this material was optional in the first place. The single flex-slide was my favorite Expansion Joint, as it was easy to use. Sometimes however my optional topic required a proper visual channel, necessitating dedicated slides. My solution here was good control over slide handling. Presentation tools include the ability to skip over slides while I'm talking, and I made sure I practiced how to use them so I could skip a bunch of slides without the audience knowing. It's crucial here that it's invisible to the audience, I find it looks sloppy if anyone says “in the interests of time I'll skip over these slides”. To do this, however, I do need access to my laptop while presenting, venues that only provide a clicker while loading the slides on some other machine lack that control. That started to happen in my last couple of years, much to my annoyance. When creating talks, I was always worried that I would run out of things to say, even though experience told me I reliably crammed more stuff in than I could possibly cover. Expansion Joints helped with this, I could aggressively trim the core talk to less than I needed, and rely on the Expansion Joints to fill the gap. In practice I usually didn't need the Expansion Joints anyway, but their presence helped my confidence. Using Expansion Joints was particularly important for me as I never rehearsed my talks. I was always someone whose ability to present was driven by adrenaline. Talking to a rubber duck just didn't work, the duck was clearly every bit as bored as I was. Consequently the first time I gave a talk, I was hazy as to how long it would take. Yet with Expansion Joints in place, I was able to finish a talk right on time. Expansion Joints enabled me to give the same talk to different time slots. Sometimes I'd have thirty minutes, sometimes forty-five. With Expansion Joints, I didn't need to change my slides, particularly handy if a time cut (or more rarely a time increase) appeared at the last moment. (Although in my later years, I handled this by doing a Suite Of Talks .) Talks that encourage audience interaction need these because we can never predict how much time the interaction will use up. Sometimes we get a steady stream of questions, other times (particularly in Scandinavia, or upper-Midwest America) a lack of questions had me blasting through the agenda. Any such talk needed a double-dose of this temporal ballast. Expansion Joints are at their most useful in later parts of the talk, as it's then that I have the most information on how much time I have. Earlier ones can still be handy, particularly if they come after an interactive section when I'd like to rebase my timing. The name was coined by Neal Ford, Matthew McCullough, and Nathaniel Schutta in their excellent book Presentation Patterns .

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Martin Fowler 2 months ago

Team OKRs in Action

OKRs have become a popular way to connect strategy with execution in large organizations. But when they are set in a top‑down cascade, they often lose their meaning. Teams receive objectives they didn’t help create, and the result is weak commitment and little real change. Paulo Caroli describes how high‑performing teams can work in another way. They define their own objectives in an organization that uses a collaborative process to align the team’s OKRs with the broader strategy. With these Team OKRs in place, they create a shared purpose and become the base for a regular cycle of planning, check‑ins, and retrospectives.

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Martin Fowler 2 months ago

Impact Intelligence, addressing common objections

Sriram Narayan concludes his article in impact intelligence by addressing five common objections to this activity, including slowing down, lack of agility and collaboration, and the unpredictability of innovation.

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Martin Fowler 2 months ago

Quick but worthwhile links

Abi Noda observes Just met with a 2000+ eng company. Their developers are saving 2+ hours per week thanks to Copilot. But they’re also losing: AI is not a silver bullet. Nik Malykhin found it useful to get an AI assistant to write its own coding rules by analyzing his code, and then asking it to refine them as worked with it. the central paradox of using AI assistants effectively: to offload cognitive work to an AI, you must first do the meta-cognitive work of codifying your own development philosophy and collaboration style. I agree with Charity Majors that there is a valuable distinction between disposable versus durable code , and that makes a difference in how we use AI with it. The difference between disposable code and durable code is not about whether the code was generated by AI or written by a human, or even how difficult it was to write. The cost is defined by the standards you are building to, and the rest of the software development lifecycle: how well you expect to maintain it, extend it, migrate it, understand its behavior, or fix it when it breaks. This is the expensive part of software development, the type that requires deep expertise and familiarity with your language and environment. Disposable code is cheap because you don’t even try to maintain it. Jim Highsmith thinks that we should think of AI as Alternative Intelligence It’s not fake intelligence, or artificial empathy, or HAL 9000 with manners. It’s something else. Something that thinks differently, not defectively. Rod Johnson asserts that we know that memory is important to AI systems, but we forget that Domain Models are an important form of memory Event Sourcing provides perfect episodic memory by storing the complete history of domain changes as immutable events. Every decision, every state transition, every business event is preserved with full context. Repository patterns offer domain-focused memory interfaces that understand business concepts. A CustomerRepository knows how to retrieve customer information in ways that preserve business meaning, not just raw data. Bounded contexts from Domain-Driven Design partition memory into semantic boundaries, preventing the concept pollution that plagues pure vector-based approaches. Aggregates function as cohesive memory clusters with consistency boundaries—exactly what we need for reliable agent behavior.

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Martin Fowler 2 months ago

Actions to improve impact intelligence

Sriram Narayan continues his article on impact intelligence by outlining five actions that can be done to improve impact intelligence: introduce robust demand management, pay down measurement debt introduce impact validation, offer your CFO/COO an alternative to ROI, equip your teams.

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Martin Fowler 2 months ago

The Reformist CTO’s Guide to Impact Intelligence

The productivity of knowledge workers is hard to quantify and often decoupled from direct business outcomes. The lack of understanding leads to many initiatives, bloated tech spend, and ill-chosen efforts to improve this productivity. Sriram Narayan begins an article that looks at how to avoid this by developing an intelligence of the business impact of their work across a network connecting output to proximate and downstream impact.

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Martin Fowler 2 months ago

How far can we push AI autonomy in code generation?

Birgitta Böckeler reports on a series of experiments we did to explore how far Generative AI can currently be pushed toward autonomously developing high-quality, up-to-date software without human intervention. As a test case, we created an agentic workflow to build a simple Spring Boot application end to end. We found that the workflow could ultimately generate these simple applications, but still observed significant issues in the results—especially as we increased the complexity. The model would generate features we hadn't asked for, make shifting assumptions around gaps in the requirements, and declare success even when tests were failing. We concluded that while many of our strategies — such as reusable prompts or a reference application — are valuable for enhancing AI-assisted workflows, a human in the loop to supervise generation remains essential.

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Martin Fowler 2 months ago

Partner with the AI, throw away the code

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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