203 articles filed under this topic.
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.
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.
Most repositories ship code and a README - this one ships four ADRs with a named approver, a context map, a domain message flow and a methodology poster. Part 1 of a series that reads the strategic half of DevMentors' GroupFlights.
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.
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.
Every modular monolith promises you can extract a module later. Inflow has a branch where someone actually did it - one module lifted into its own process behind a gateway and a real broker. This series reads that branch line by line.
DevMentors built the same e-commerce shop twice - once as a monolith, once as nine services - with two gateways and two frontends. This series reads the whole estate as one artefact.
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.
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.
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.
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.
DevMentors shipped Trill as nine microservice repos, then rebuilt the identical product as a modular monolith three months later - giving us a controlled experiment in architecture that almost never exists in public.
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.
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.
Thirteen repositories, one umbrella that runs twelve of them, two interchangeable API gateways and a service that watches everything - the Pacco estate read as a system of systems, and the fifteen-part series it earns.
Convey's real manifest is not Program.cs — it is the config file. Reading the Orders sample's appsettings.json as a single artifact: the section-per-package convention, the fleet of enabled:false switches, and what the defaults quietly tell you about production.
Convey.Persistence.OpenStack.OCS is the package the whole first series skipped — a hand-rolled Swift object-storage client with Keystone auth, an operation-result pattern, a server-side COPY verb, and a re-authentication habit worth learning from.
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.
Pactify.AspNetCore in one sitting: an attribute, an assembly scan, and a /pacts/{provider} endpoint that serves your contract classes as live JSON - plus what a runtime contracts endpoint is really for.
The series retrospective - what a thirty-file library taught me that a full-featured one couldn't, Pactify's honest limit list versus PactNet, the broker maturity ladder, and the org-shaped question hiding under the tooling.
A line-by-line read of Pactify's matching engine - top-level-only body comparison, header names that ignore your casing option, nested objects that can never match, and two format-string bugs that crash the error path.
How a pact travels from the consumer's pipeline to the provider's - Pactify's file and HTTP publishers, Pact Broker URL anatomy, and the unchecked response status that makes a failed publish silently pass your build.
The provider side of Pactify - how CreateFor<Startup> hosts your whole API in memory with TestServer, why interactions verify concurrently, the SmartFormat trick behind endpoint templating, and the discovery that Given(...) never runs.
An annotated tour of the JSON document Pactify produces - the serializer settings that shape it, the snake_case field inherited from Pact v1, and the unusual decision to ship the consumer's matching options inside the contract itself.
A walk through Pactify's PactMaker fluent API - the two-interface builder trick that hides Build() from you, why the consumer test always passes, and the uninitialized-object surprise inside WithBody<T>().
The retrospective: after ten parts inside DevMentors' real-time feeds sample, the honest scorecard - five decisions worth stealing for real systems, the sharp edges catalogued in one place, and the concrete backlog that separates this teaching codebase from a production deployment. Part 11 closes the FeedR deep dive.
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.
FeedR ships three ways to run its six services - pm2, Project Tye, and a deliberately split pair of docker compose files - plus per-service Dockerfiles and an environment-keyed configuration layer that lets the same build run on localhost and inside a compose network. Part 10 of the FeedR deep dive.
FeedR threads a correlation ID from a YARP transform through HTTP middleware and into Pulsar message metadata - and quietly loses it at the Redis hop in the middle. Tracing exactly where the chain holds and where it breaks is the best observability lesson in the sample. Part 8 of the FeedR deep dive.
How do you assert that an endpoint published an event when publishing is a side effect with no return channel? FeedR's end-to-end test answers with WebApplicationFactory, a real Redis round-trip, and a TaskCompletionSource - plus the timeout and determinism traps the sample leaves open. Part 9 of the FeedR deep dive.
Where FeedR's data graduates from tick to fact: the aggregator's pricing handler, a second messaging seam with envelopes and metadata, Apache Pulsar as the durable tier, and the notifier's acknowledge-as-you-go consume loop. Part 7 of the FeedR deep dive.
FeedR pushes live prices to clients through a gRPC server stream: a four-message proto contract, fixed-point decimals, dual Kestrel endpoints, and an event-to-stream bridge that busy-spins - plus the channel-based rewrite it's asking for. Part 5 of the FeedR deep dive.
FeedR's weather feed is the pattern for every external integration: poll a REST API inside an IAsyncEnumerable, guard it with a typed HttpClient and Polly retries, translate its JSON at the boundary, and republish it as a push. Plus the retry clause I can't defend and a hard-coded API key with a lesson in it. Part 6 of the FeedR deep dive.
FeedR moves every tick between services through a two-method streaming abstraction with a no-op default and a Redis implementation - which, despite the namespace, is pub/sub rather than streams. What that seam buys, how DI last-wins overrides it, and what you lose when nobody is listening. Part 4 of the FeedR deep dive.
How FeedR's quotes feed decouples a microsecond HTTP endpoint from an hours-long price generator: System.Threading.Channels as a command queue, marker records as the protocol, and an Interlocked flag for idempotent start/stop. Part 3 of the FeedR deep dive.
FeedR's API gateway is a YARP reverse proxy whose entire routing table lives in appsettings.json - prefix-stripping routes, per-environment cluster overrides, and a one-line transform that starts every distributed trace. Part 2 of the FeedR deep dive.
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.
How Convey stitched one Jaeger trace across HTTP, a command handler and a RabbitMQ hop years before OpenTelemetry - and the six-line catch block in its tracing plugin that can silently eat your failures.
Closing the series with an honest audit of the chassis - which of Convey's ideas still earn their keep in 2026, which ones the platform absorbed, and what I would build differently today.
Convey ships two metrics packages that answer the same question from different eras - a push-flavored App.Metrics stack and a lean prometheus-net scrape endpoint - and the choice between them is a history lesson.
