Series · 15 parts
An Attendance Platform in ASP.NET Core
Badge gates, WFH timers and shift allowances - the shape of a seven-project intranet attendance platform, the onion it almost is, and the roadmap for fourteen more parts.
Topic
.NET
348 articles filed under this topic.
Series in .NET
Series · 4 parts
An Attendance Platform — The Frontend Chapters
A 6.23 MB JavaScript bundle loaded on every page, a manifest that minifies CSS but concatenates JS, and two copies of jQuery - the first of four frontend chapters the attendance series skipped.
Series · 9 parts
Archive-on-Delete with ArchiveKit
Hard deletes destroy the audit trail; soft deletes clutter live tables forever. Introducing ArchiveKit, a .NET library that intercepts deletions and stores immutable archive snapshots with TTL policies and cascade archiving.
Series · 8 parts
Contract Testing with Pactify
Unit tests mock what you assume, end-to-end tests tell you too late - consumer-driven contract testing closes the gap, and a small open-source .NET library called Pactify is the clearest way I know to learn how it works. Part 1 of a series.
Series · 8 parts
Convey — The Missing Chapters
The 22-part Convey series read the packages; it never once walked the sample system that ships with them. Opening the missing chapters with the trip an order takes through Orders, Pricing and Deliveries — and what the samples quietly teach that no package README does.
Series · 10 parts
Entity Versioning with VersionKit
Rename a property, change a type, ship the release - and every payload you stored last year stops deserialising. Introducing VersionKit, a .NET library that declares schema history as attributes and migrates old data on read.
Series · 17 parts
FastEndpoints in Depth
Controllers grow sideways and Minimal APIs grow into soup. FastEndpoints bets on a third shape - one class per endpoint - and this series reads its source to see how the bet is implemented. Part 1 of FastEndpoints in Depth.
Series · 12 parts
FastEndpoints — The Missing Chapters
Seventeen parts of reading FastEndpoints and the series never once mentioned mappers - the entity-translation layer half the endpoint base classes exist to serve. The Missing Chapters opens with the biggest gap: where mappers live, how they are found, and why they are secretly singletons. Part 1 of FastEndpoints — The Missing Chapters.
Series · 15 parts
Five Modules, One Database Each
Inflow is a modular monolith whose modules agree on their boundaries and disagree about everything inside them - a four-project onion next to a single feature-sliced assembly. Part 1 of a series reading the money-moving half of the estate.
Series · 18 parts
GroupFlights — Tactics in Three Dialects
A teaching repo that implements one airline-charter domain three ways on purpose - CRUD, CRUD-plus-rich, and Clean Architecture - and persists it three ways to match. Part 1 of a source-reading series.
Series · 22 parts
Microservices with Convey
Every team's fifth microservice ships with the same four hundred lines of bootstrap code as the first four. Opening a deep-dive series on Convey, the open-source .NET toolkit that turned that boilerplate into thirty composable packages.
Series · 10 parts
Multi-Tenancy in .NET with EF Core
Database-per-tenant, schema-per-tenant, or packed into a shared database? Kicking off a series on building a multi-tenant platform where one EF Core codebase supports all three isolation strategies behind a single control plane.
Series · 15 parts
Nine Services and a Message Bus
DShop is one e-commerce shop stamped out as nine microservices over RabbitMQ - this series reads the real source to see how the topology holds together and where it drifts. Part 1 of Nine Services and a Message Bus.
Series · 13 parts
No Coding Whatsoever
A 2018 API gateway promises that routing, auth, validation and messaging need no code at all - this series reads the source that makes the promise true, and the places where it is not.
Series · 14 parts
One Process, Three Modules
DevMentors' ModularMonolith sample packs three conference-system modules, a mini-framework and one deliberately broken contract into eighty-four C# files - opening a series that reads all of it, defects included.
Series · 11 parts
Real-Time Feeds with FeedR
A guided tour of FeedR, DevMentors' open-source .NET microservices sample for real-time data feeds - six services, Redis pub/sub, Apache Pulsar and a gRPC stream, and the two-tier eventing model that makes it worth reading. Part 1 of a source-level deep dive.
Series · 9 parts
Sagas with Chronicle
Split one database into five services and the transaction you deleted does not disappear - it goes feral. On sagas, compensation, process managers, and Chronicle, the small open-source .NET library this series reads line by line.
Series · 8 parts
Service Discovery Without a Service Mesh
Dozens of Azure Functions and Logic Apps need each other's URLs and keys, and there is no Kubernetes, no sidecar, no mesh to hand them out. How a small .NET library turned one Key Vault and a naming convention into a working discovery layer - the consumer side of a registry made of secrets. Part 1 of a new series.
Series · 11 parts
Six Packages and an Empty Test Project
Reading a repository one project at a time hides everything that lives in the edges between them - and in this estate the edges are where the interesting failures are.
Series · 13 parts
The Convey Consumer Tax
Convey sells a microservice in thirty lines, and Pacco builds ten of them - this series reads the whole estate to price what the framework compresses and what every consumer pays for by hand. Part 1 of The Convey Consumer Tax.
Series · 18 parts
The Database Is the Message Bus
Five executables, zero queues - how an attendance platform coordinated a web app, three Azure Functions and a console job through one SQL database, and what that choice bought and cost. Part 1 of the series.
Series · 16 parts
The Framework Before the Framework
DShop.Common is the shared library nine microservices were built on - and the rough draft of a framework its authors later shipped as Convey.
Series · 15 parts
The Framework Underneath
Every modular monolith claims its modules are decoupled. Inflow proves it the only way that counts - by having no project reference between any two of them - and then has to build a whole mini-framework to make that survivable. Part 1 of a source-read through the shared layer.
Series · 15 parts
The Order That Choreographs Itself
Nobody in Pacco approves an order - a vehicle reservation does. A tour of DevMentors' parcel-delivery estate, the domain it models, and the fifteen-part series it earns.
Series · 11 parts
The Repo Is the Lesson
Inflow ships an executable request collection - five .rest files, thirty-seven requests. On a fresh clone nine of them return a 2xx, and eight of those nine are in one file. This series reads the repository itself as the artefact.
Series · 15 parts
Trill — Reading the Services
Trill's Stories service is four projects with a dependency-free domain at the bottom. Its Users service is two projects with everything in one assembly - same author, same week, same estate, opposite answers to what a layer is.
Series · 15 parts
Trill — The Microservices Spine
The DevMentors Trill estate is a nine-service microservices sample spread over eleven sibling repositories with no README, no clone script and no bootstrap tooling - and the only artefact that names the whole system is a Visual Studio solution file.
Coming soon · 1 part
Aspire in Production
What .NET Aspire actually does for a real multi-service system - the AppHost model, service defaults, the dashboard, and the road from F5 to deployment.
Coming soon in .NET
The Dashboard You Get for Free
Wire four services into a .NET Aspire AppHost and run it once - traces, logs, health and environment variables for the whole system, before you have written a single line of observability code. Part 1 of a series on Aspire in production.
Standalone articles
26 Apr 2025
Getting Transactions Right with EF Core
SaveChanges is already a transaction, until it isn't enough. A tour of explicit transactions, TransactionScope, execution strategies and the failure modes that only show up in production.
Everything in .NET
The Wallet That Adds Itself Up
Inflow's Wallet has no balance column - the balance is a fold over the transfer ledger, computed the same way on the write side and the read side. It is the best decision in the module, and it costs more than it looks.
Four Architectures in One Solution
Inflow is a modular monolith whose modules agree on their boundaries and disagree about everything inside them - a four-project onion next to a single feature-sliced assembly. Part 1 of a series reading the money-moving half of the estate.
Seven Lines of CSS for Twenty Components
Trill's Blazor WebAssembly client has twenty Razor components, thirty-seven inline style attributes, two authored class names and one stylesheet containing a single rule - and the thinness is not an oversight, it is the most precise measurement of what a teaching repository is.
Seven Test Projects, Zero Tests
An honest retrospective on Trill's five services and its client - twelve xunit scaffolds with no test files and no project references, a green test script over nothing, and a defect list where almost every entry would have died to a four-line assertion.
An Ad Is a Story With a Flag
Trill's entire advertising product resolves to one boolean on somebody else's entity - a published ad is a Stories-service story with Highlighted set true - and the flag is priced at a hundred units a day while the same field is free on the public endpoint.
Fan-Out on Write, One Round Trip at a Time
Trill's Timeline service stores each story body once and fans out only the identifier into every follower's sorted set - the right hybrid design, executed as a sequential foreach with one Redis round trip per follower and no batching anywhere.
Trending Means All-Time and Frozen
Trill's entire ranking engine is thirty-nine lines of OrderByDescending().Take(10) over counters that only ever increase - no time window, no decay, no visibility filter - so once the top ten stabilises it can never change again.
One Format String, Two Meanings
The same .NET format specifier means thirty-two hex digits on a Guid and a grouped decimal on a long - and Trill's timeline writes its sorted-set members one way then reads them the other, so every non-empty timeline throws.
Sign-In Is Impossible If You Capitalise
Trill's User constructor stores the name trimmed but not lower-cased, and the repository looks it up lower-cased. Any account with a capital letter in its name can never be found, which means it can never sign in - and the test fixture is all lowercase.
The Identity Abstraction Nobody Injected
Trill's Stories service ships a complete caller-identity abstraction - context, factory, claims, an IsAdmin flag - registers it in the container, and injects it into nothing, while every endpoint reads the user id out of the request body instead.
A Million Documents for One Integer
Trill's browse endpoint loads every rating document for every story on the page into process memory and sums them in LINQ - while the same codebase already has a server-side SumAsync that returns the number without moving a single document.
An Index With Its Keys Backwards
Trill creates one compound index on its ratings collection, keyed userId then storyId, and every read query in the service filters on storyId alone - so the only index that exists cannot serve the only queries that run.
Six Decorators and One Marker Attribute
Trill wraps every command handler in logging, metrics, tracing and an outbox using Scrutor's TryDecorate - and the whole arrangement only works because a single attribute keeps the decorators out of the assembly scan that registers handlers.
The Refactor That Stopped Halfway
Trill's last commit built a complete domain-event pipeline - dispatcher, mapper, handlers - and migrated one of the two command handlers onto it. The other still constructs its aggregate directly, so one domain event is never raised and a reputation gate can never fire.
The Factory That Doesn't Own Construction
Trill extracts story-text validation into an IStoryTextFactory and leaves the value object's constructor public - plus an implicit conversion from string, so any assignment builds an unvalidated StoryText in one keystroke.
Title and Text, Swapped Since Commit One
StoryDocument.ToEntity passes the body where the title goes and the title where the body goes. It compiles because of one implicit conversion operator, and it has survived since the first commit because the only code path that would notice is dead.
Two Services, Two Architectures
Trill's Stories service is four projects with a dependency-free domain at the bottom. Its Users service is two projects with everything in one assembly - same author, same week, same estate, opposite answers to what a layer is.
Everything Observed, Nothing Survivable
Trill ships Jaeger, Prometheus, Grafana, Seq, Consul and Vault, and contains no circuit breaker, no dead-letter queue, no health check and no alert rule - the closing retrospective on what this estate gets right, what it does not, and when not to build a system this way.
The Second Architecture, Switched Off by Comment
Trill contains a complete synchronous integration architecture - typed gRPC and HTTP clients, a live gRPC server, generated stubs, an options class - that was built, wired and then disabled by commenting out three lines across two repositories.
Two Contracts Drifted, Twelve Did Not
Trill has no shared contracts package - every consumer re-declares the publisher's event class by hand. Diffing all fourteen duplicated contracts shows exactly two have drifted, and the ratio is what makes copy-paste governance feel safe until it isn't.
A Saga That Cannot Compensate
Trill's ad-publication saga implements Compensating Action in five overrides and can reach none of them - the rejection events it subscribes to carry no correlating id, their handlers return Task.CompletedTask, and no handler ever throws.
Every Disconnect Eats a Message
Trill's push service checks its cancellation token after dequeuing rather than before, so a disconnected client wins one more message from the shared queue and destroys it - and the Blazor client that consumes the stream never reconnects.
The Filter That Drops the Future
Trill's push service gates stories on a visibility window and silently discards anything scheduled for later - a Message Filter where a delay was intended, with no scheduler, no delay queue and no re-delivery anywhere in the estate.
A Channel Is Not a Topic
Trill's push service fans stories out with a single System.Threading.Channels queue - which means every connected browser competes for the same message instead of all receiving it, and the class name is plural while the field is not.
The Policy That Was Never Applied
Trill's gateway declares an authenticatedUser authorisation policy exactly once and attaches it to nothing - and its identity middleware returns early when the Authorization header is absent, so a caller with no token at all can publish commands onto the estate's message bus.