Paul Grenyer

I’ve given my Beyond the Code: Designing Services That Stand the Test of Time presentation a few times now. It started as a talk I put together for the ACCU Conference - which wasn’t accepted - and has evolved quite a bit as I’ve presented it to different audiences, and had conversations with people afterwards. The original idea was fairly simple. As software engineers, we spend a lot of time thinking about business logic. We think about the domain model and how to operate on it, the workflows, and the data. These things are obviously important, but a service is more than its business logic. The things around that logic matter too. How the code is structured. Where responsibilities live. How components communicate. How we expose functionality through APIs. How we deal with failures. How we observe what the system is doing. What we test, and how. These decisions can have a significant impact on how easy a service is to understand, maintain and change. Because while almost everything ab...

I really like Lukasz Quilter and his little band, they get into some fantastic scrapes. A Sound Inhuman has a gloriously gory beginning and then builds really nicely. I like a sci-fi story which creates lots of questions, which gradually get answered as the story progresses. This story has that in spades. However, there are two mysteries which go unanswered, and aren’t part of the setup for the next story, which is a shame. There are lots of characters to get your teeth into, which is great as they’re all quite different, and the dynamics between them work well. Personally, I can’t wait for the next Lukasz Quilter story. I hope it will be longer, with more Space Opera. I am a bit biased though, as the author is a long term friend and was kind enough to dedicate this story to me. A Sound Inhuman: A Lukasz Quilter Novel Ray Adams ISBN-13: ‎ 979-8198705548

Surrounded by Idiots: Entertaining, Thought-Provoking, but Don't Take the Colours Too Literally Thomas Erikson's Surrounded by Idiots is one of those books that's easy to see why it became a bestseller. It's funny, engaging and full of memorable examples. It starts well with a sense of humour - the "keep the receipt" joke immediately sets the tone - and throughout the book Erikson has a knack for making behavioural psychology feel approachable rather than academic. One of the first ideas that struck me was his challenge to the Golden Rule. Rather than treating others as you would like to be treated, he argues you should treat people as they would like to be treated. It's a simple shift in thinking, but one with obvious implications for communication, leadership and relationships. The core of the book is the familiar DISC model, expressed as four colours: 🔴 Red – task-oriented extroverts who focus on results and action. 🟡 Yellow – relationship-oriented ex...

In June 2026, a new HTTP request method, or verb, was introduced. RFC 10008 describes Query as: A QUERY requests that the request target process the enclosed content in a safe and idempotent manner and then respond with the result of that processing. This is similar to POST requests, but QUERY requests can be automatically repeated or restarted without concern for partial state changes. But what does that mean and why do we need it? What’s Wrong with GET? When we want to retrieve a resource from a RESTful interface, we use GET. It’s simple. It’s easy to use. A GET request has no defined request body, and it should be idempotent. That means we can make the same request over and over again without changing any state in the service. The response itself might be different if the resource has changed, but the GET request shouldn't be the thing that causes that change. Sometimes we need to add query parameters to a GET request. Perhaps we want to specify the maximum number of resources ...

I’ve been doing a kind of tour with my Beyond the Code: Designing Services That Stand the Test of Time talk. I’ve given it in Oxford, Norwich, Cambridge, London and York*, between February and August this year. I’ve really enjoyed giving it, but what I’ve loved the most is the feedback and the energy (sorry for the cliche) of the audience.  In Oxford they ripped my logging examples to shreds. In Cambridge I couldn’t convince anyone of the merits of sharing data - so I reframed it in terms of caching. In Colchester they were convinced that it was fine to return a success indicator in a HTTP response body - this resulted in me writing, Should HTTP Status Codes Reflect Business Outcomes? . And in London someone started arguing after just the second slide, but they, and the rest of the audience, went on to ask rich and engaging questions. In Norwich, my home city, and off the back of me describing what had gone on in Colchester a few weeks before, a couple of different people asked me...

The Machine Crusade is mostly another middle of the road science fiction story, like The Butlerian Jihad , however what saves it are moments of brilliance from time to time and the ending, which accelerates considerably and keeps you wanting more. There are many characters, and I wish I’d made a note of who was who and where they came from and how they were related at the start. However, the characters are quite rich, making this a more enjoyable read. This felt a bit more like a Frank Herbert story, as most of the characters were selfish, narcissists driven by power and wealth. The robots are more believable than before, but the story is starting to date when you consider it in the context of modern AI. I’m pleased I read it. I’m looking forward to the third and final instalment. Let’s see where this goes. Brian Herbert, Kevin J Anderson ISBN-13 ‏ : ‎ 978-1848943414

I don’t usually enjoy ‘art’, however I’m often in museums as my wife enjoys it. We’re on the Victoria and Albert Museum (V&A) mailing list - mostly because my wife wants tickets for the David Bowie exhibition - and an email about the new Bharti Kher (https://bhartikher.com/) exhibition: Hybrid forms and lived realities: the sculpture of Bharti Kher  looked like her sort of thing, so we went. It consists of four sculptures, one outside at the front of the museum and three intermingled with other sculptures in one of the main concourses. My initial thought was that we’d gone all that way, and it was just four sculptures, and I should have read the V&A article properly. The thing is though, they were really good, imaginative and right up my street. I particularly liked Warrior with Cloak and Shield: and even though Ghost looked like a statue that had got out of the shower and taken the shower curtain with it, I really liked it: Animus Mundi: and Gaia were equally impressive....

There’s something about Software Crafters Cambridge - and it’s not just that I can never remember the order the words go in the name. They’re a quiet group of software professionals, but the talks and workshops are always interesting, and it quickly becomes apparent that there’s a lot of knowledge and experience in the room. I’ve known Carl Farmer for several years. I helped him set up SyncIpswich back in the mid-teens. However, I hadn’t seen him for ages, so I was keen to come along and hear what he had to say. I wasn’t disappointed. Carl works in AI at Microsoft as an AI Solutions Engineer - sales, basically - so he’s seen it all. He took us expertly through how to measure the real ROI of AI. It turns out it’s the same way we measured it with human engineers; we just mustn’t forget to keep doing it that way. Carl then explored ways of working with AI, how to get the most out of prompts, and how to minimise costs. I came away with a lot of notes and useful tips. The part that resona...

I hadn’t written a line of C++ since 2011 before I read this book, and that was just for fun. I hadn’t written a line professionally since 2006. Introducing C++ made me want to write some C++ again, so I did. Early in the book, Frances tells us that prior knowledge of another programming language is useful when reading the book. A lot of what I had forgotten about C++ came back very quickly - I think I would have struggled without prior programming knowledge. However, if you don’t know another language, or C++, already, don’t let that put you off picking it up - give it a try! Introducing C++ is very easy to read throughout, and that is its biggest strength. The introduction to the language is gentle until about the final quarter. There is a great introduction to class basics, and then the pace picks up considerably. The example code is introduced a little at a time and used to build a trading game throughout the book. This worked really well for me. The book certainly left me wanting ...

We saw Skunk Anansie just over a year ago and I haven’t seen Garbage since the Version 2.0 tour in 90s - the best time to have seen them in my opinion. When the opportunity to see them both together came up, of course Charlotte wanted to go - despite it being half way across the country. Soon after we bought the tickets, Garbage announced a gig at the Roundhouse, which would have been closer, cheaper and far more convenient. Support came from Ian Davies and Du Blonde. We eventually figured out that the DJ playing when we arrived was Ian Davies, he had some good tunes, especially when he kept to the 90s.  Du Blonde was quite good, the sort of Indie Rock band which were common in the 90s, singing about similar themes, such as the music industry. Probably the best which can be said about Garbage is they were good. The two guitarists were lackluster, but of course Shirley Manson was great, marching around, in bright red boots, like she owned the stage - which of course she did. Great ...

I Asked an AI to Build Me a Bank Data Platform. Here's What Happened. Claude wrote this post for me and we reviewed and revised it together. I know this won't be popular with at least a few of my regular readers, but it felt like the right thing to do given the project it's describing.  Lambdas don't play well with RDS databases. Connection pooling, VPC cold starts, idle timeouts — it's a well-documented headache. But a Lambda is the obvious choice for a cloud-native Open Banking API implementation. And RDS is usually the best choice when you want to query and analyse data. I'd hit this tension before and never resolved it cleanly. So I wanted to see if Apache Iceberg could be the answer. It works with Lambdas (just write Parquet files to S3), and it can be queried like a relational database via Spark or Athena. I was also keen to see what the Lambda integration actually looked like in practice. I decided to pair with Claude Code on the build — treating it...

I have been reviewing Fran Buontempo's new C++ book , and somewhere between the chapters on modern idioms and the bits where she nudges you to actually do something with the language, I caught the itch. I have not written any C++ in more than twenty years, and the book reminded me how much the language has moved on without me. I wanted to host something small, written in modern C++, on a URL I could share. This project is the result. The brief I gave myself was deliberately tiny. A single HTTP endpoint that returns `Hello, World!`, built in C++, deployed somewhere real, with the whole thing reproducible from a fresh checkout. The point was not to ship a product. For the HTTP layer I picked  Crow , a header-only framework with a Flask-shaped API. Header-only matters here because it keeps the build simple The whole server is twelve lines: #include <crow.h> int main() {     crow::SimpleApp app;     CROW_ROUTE(app, "/")([]{         return ...

Sometimes, even when you’re close to your team, patterns or underlying issues emerge over time. Some of these are insights you may wish you had recognised earlier. The important thing is to talk to your team and work on a solution together. Sometimes, together you resolve one challenge and enhance something else at the same time Like many teams, we’ve been through many Pull Request (PR) process evolutions. We started with requests in Microsoft Teams chats - they often got lost. We tried automated notifications in  Teams, but they were only possible in an odd place - so they got ignored, and lost. Then we created a chat for our team just for PRs, with a strict no chat policy, and an emoji system so engineers can see someone is looking at their PR, when there are comments, when it’s approved, and the engineer can even mark it as urgent if necessary.  It worked really well, until something unforeseen happened. The Challenge I realised that one of my engineers was taking on the ma...

  On Tuesday this week, I was back at AWS on Holborn Viaduct learning about Apache Iceberg with a colleague. Iceberg is a table format standard for managing large-scale datasets and their metadata. The AWS-managed approach is to store the data in S3, meaning you only pay for storage and bandwidth. Other tools, such as Apache Spark , can then be used on top to build a data warehouse - or in this case, a Lakehouse. AWS also supports self-hosting, but this requires you to configure and manage aspects such as maintenance yourself. One of the major advantages Iceberg has over other data warehouses is its support for True ACID transactions, and its table format standard means you don’t have to run a database engine. Anything which wants to access the data can go straight to S3. As a software engineer with a background in object orientation, this feels potentially brittle and a coupling nightmare, but I am sure it works in practice.   The pre-workshop presentations made Iceberg feel...

I’ve delivered my Beyond the Code: Services Which Stand the Test of Time presentation a handful of times this year. Toward the end of the first half, I take a stronger stance and talk more directly about the design of RESTful interfaces. Most of the material in the presentation is framed as guidelines rather than hard rules. However, the RESTful section leans much more strongly toward rules, and there’s one rule in particular that I consider non-negotiable: Never, EVER, use a field in a response to indicate success! Then I show this example on the next slide of why you shouldn’t do it: Just in case it isn’t immediately obvious, there is a conflict here between the HTTP status code of 200 , indicating everything is OK, and the success field in the response body saying that it isn’t. Usually this gets a knowing, sometimes uncomfortable laugh from the audience, but not tonight in Digital Colchester. One audience member challenged this stance with a question I’ve been thinking about since...

I really enjoyed Foundation’s Edge and I had great expectations of Foundation and Earth.  I was disappointed. About 90% of the story just plods on. Then the last 10% is really good, but goes super fast. I think part of the problem is that Asimov was told to write longer books and this has resulted in padding in the form of the character constantly discussing and rediscussing the same points. More frustratingly, it doesn’t finish the psychohistory story and there are no further books in the series. Written only six years before the author's death and followed by two sequels, perhaps there just wasn’t enough time. Some of the sexism from the earlier books is back. It’s very much a book of its time and Asimov's apparent attitude. With Foundation done, I’ll be progressing to Asimov's robot books. Isaac Asimov ISBN-13: 978-0008117535

Great Band. Great Set. Great Venue. Great Sound! Need I say more? I will… We loved the Shepherd's Bush Empire the first time we went in December 2023 for Paradise Lost and My Dying Bride, so we were really excited to be going back. It didn’t disappoint. We had some good seats in the balcony and the sound was so much clearer than a lot of other venues we have been to over the last few years (I’m looking at you, The Roundhouse!) The openers were a French three-piece metal band called Lizzard, who were completely new to me. They were progressive, heavy enough, and incredibly tight. Their songs were long, with extended instrumental sections, which I really enjoyed. I loved it! I’ll definitely be listening to more. I’ve been into The Gathering since I heard Nighttime birds. I like all of their albums, but my favorites are the Anneke van Giersbergen era including Mandylion, How to Measure a Planet, If Then Else and Souvenirs. I first saw them around the time of How To Measure a Planet, s...

I’m currently working on a new piece of writing that I’m hoping to present next year, and I’d really value your input.  To support this research, I’ve created a short survey to gather perspectives, experiences, and insights. Whether you’ve got strong opinions or just a few minutes to spare, your response would make a genuine difference. Why take part? Your feedback will directly contribute to real research It only takes a few minutes to complete You’ll be helping shape something meaningful and (hopefully!) impactful I’m aiming to build a deeper understanding of the topic, and every response helps create a clearer, more balanced picture. Take the survey here:   https://forms.gle/VCqJdJz248awjyjNA Thank you so much for your time and support, it’s greatly appreciated!

For a book divided into small, discrete and easily absorbable chapters, there’s a lot of Clean Architecture.  Its strengths are the discussion of the SOLID Principles, Compensation and insistence on abstract interfaces, encapsulated concrete interfaces, loose coupling and cohesion - every software engineer should read it just for these. Its weaknesses are the verbosity and its heavy bias towards object orientation and dependency injection, but then it’s a book of its time. The open minded reader will see through this and realise that Clean Architecture is applicable and applicable everywhere. There’s a long appendix which, although quite self indulgent, is actually really interesting and I’m glad I persevered with it. Clean Architecture: A Craftsman's Guide to Software Structure and Design: A Craftsman's Guide to Software Structure and Design (Robert C. Martin Series) Robert Martin ISBN-13: 978-0134494166

When One Beyond invited me to take part in the London Tech Leaders Summit, I wasn’t quite sure what to expect. What I definitely wasn’t expecting was a seven‑foot robot interrupting the opening welcome. As the doors flung open, the robot ducked to fit through, marched to the side of the stage, interrupted the speaker, and proceeded to continue the welcome itself. It was initially a little unsettling, but to be fair, its jokes were better. What followed was a full day of presentations, panels, roundtable discussions, and workshops. All were framed through a leadership lens and all centred on AI. I know what you’re thinking: not another AI conference. But this one really stood out. Rather than theoretical hype, it was software leaders - many in similar roles to mine - openly sharing what they’ve learned from using AI, where it’s taken them, and how it’s shaping their organisations. There were several highlights. Hywel Carver , CEO of Skiller Whale , made a particularly memorable point:...