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
Two Flags, Four Systems, One That Stalls
Two booleans govern Inflow's messaging spine. Taking their product gives four behaviours - one shipped and working, two working differently, and one that throws a NullReferenceException every second forever because the component that would prevent it only exists in another cell.
The Outbox That Commits Somewhere Else
Inflow ships a complete transactional outbox - table, poller, cleanup jobs, type registry - and one CreateScope() call means the outbox row commits on a different DbContext from the state change it is supposed to be atomic with.
Nine Lines Stop a Stack Overflow
Inflow registers every handler by assembly scan and then wraps them in decorators. Those two techniques are incompatible unless something tells the scanner to skip the decorators - and in this codebase that something is a marker attribute with no tests and no comment explaining what it prevents.
One Assignment Freezes Every Trace
Inflow carries request identity across its async message boundary in a static AsyncLocal. The line that populates it uses null-coalescing assignment inside a long-lived loop, so every message after the first runs under the first one's correlation id, trace id and user.
The Bus That Never Leaves the Process
Inflow's message broker is eighty-eight lines with a three-way branch, backed by an unbounded channel and a single background reader. Reading it shows where the delivery guarantee actually is - and that on shutdown, whatever is still queued is discarded without a log line.
Four of Eighteen Copies Are Checked
Inflow's boot-time contract verifier is excellent and almost unused. A census of every consumer-side type copy in the estate shows four protected and fourteen not - and the two failure modes are a startup crash and a silently null property.
The Round Trip That Copies Every Message
Inflow isolates modules by serialising every message to JSON bytes and deserialising it into the receiver's own type - once per receiver. It is the Message Translator done well, and the byte array in the signature tells you exactly which transport it was built for.
Local Contracts, Verified at Boot
Inflow lets each module own a private copy of every event it consumes, then type-checks those copies against the producer at application start. It is consumer-driven contract testing with no broker, no schema registry and about 280 lines - and the check is weaker than the ceremony suggests.
A Namespace Segment Is a Routing Key
One method in Inflow returns the third segment of a type's namespace, lower-cased. Four subsystems route on that string, and nothing anywhere validates it - a namespace rename is a silent behavioural change across the estate.
Your Type Name Is the Wire Contract
Inflow has no subscribe call and no topic string. A module receives an event by declaring a class with the same simple name, and a single attribute decides whether the delivery is allowed - with a cache that changes the decision, not just its speed.
The Bootstrapper Is Seventy-Six Lines
Inflow's host knows nothing about its five modules - it finds them by scanning DLL filenames and reflecting for an interface. Reading the loader shows why the whole estate is that small, and where a missing settings file silently deletes a module.
Five Modules That Cannot See Each Other
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.
The Tests That Document the Bug
Inflow has nine tests, all in one module, and the most interesting one asserts a defect as if it were the specification. The honest retrospective on five modules, four architectures and what the estate actually teaches.
Compensation That Cannot Fire
Inflow's one real saga has four compensation methods and no message that can ever trigger them. Its state lives in memory, its ordering rests on an undocumented property of a background service, and its failure mode is a denied bonus recorded as success.
A Saga Held Together by a String
Inflow's withdrawal flow is a three-module round trip with a compensating branch and no saga class. The correlation between the halves is a magic string declared three times and a JSON blob written by hand on one side and deserialised on the other.
Lock the Customer, Half the Estate Notices
Locking a customer flips a flag in three of the four modules that hold one. Wallets has Lock and Unlock methods on its Owner entity and nothing in the estate ever calls them - so the module that moves money is the module that never hears.
One Guid, Five Customers
A single Guid minted at sign-up becomes a user, a customer, a payments customer, a wallet owner and a saga id - four Postgres schemas, five field names, zero foreign keys and nothing that declares the equality.
Onion Versus Folder
Wallets is four projects, Payments is one, and the same author wrote both in the same week. Three claims are usually made for the extra assemblies - one is true and verifiable in XML, one is weaker than it looks, and one is provably false.
The Read Side the Layers Lost
Wallets abstracts its queries behind a storage interface that returns aggregates and maps in memory. Payments injects the DbContext and projects in SQL. On the read path the layered module is the slower and more coupled one.
Money Without a Currency
Inflow models money as an Amount that wraps a bare decimal and a Currency that lives beside it on the entity. The two never travel together, nothing rounds, and the column is unconstrained numeric.
The Version That Counts to Two
Inflow's aggregate root increments its Version at most once per instance lifetime. As a concurrency token that is correct; as a version number it is a lie - and the one unit test that touches it documents the latch instead of catching it.
A Setter on the Ledger
Inflow's Wallet guards its transfers behind a private HashSet and then exposes a public setter for it. Assigning an empty list zeroes any balance with no exception, no version bump and no trace - and Entity Framework never needed the setter.
The Reference That Points at Itself
Each half of an Inflow transfer stores a referenceId in its metadata. On both legs that reference is the leg's own id - so the two halves of a transfer cannot be joined from the data they persist.
Two Aggregates, One Method
Wallet.TransferFunds mutates a second aggregate root inside the first one's method - the textbook DDD violation, committed for a good reason. The reason survives the domain layer and does not survive the handler.
A Million Is Where the Wallet Breaks
Inflow's Amount value object rejects anything above one million, and the wallet balance is an Amount. Two legal credits of six hundred thousand leave a wallet that can still take money in and can never be read or spent again.