132 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.
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.
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.
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.
Eight parts of source-reading later, the honest retrospective. What Chronicle gets right, the timeout-shaped hole at its centre, how it stacks up against MassTransit and NServiceBus and durable execution - and the cases where a status column beats every saga framework ever written.
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.
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.
Convey's messaging abstraction is two interfaces and an attribute - and the naming conventions underneath them quietly turn your C# class names into a public wire contract.
Chronicle ships two persistence integrations, and reading them against the contract is a masterclass in provider sharp edges: a Redis key built from Type.GetHashCode() that changes on every restart, a Mongo delete-then-insert, and messages that may not survive the round trip.
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.
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.
The retrospective, with the ledger totalled - seven byte-identical MessageBrokers, one AggregateRoot with three meanings, what Convey genuinely optimises, where a Convey.Bootstrap meta-layer should have stood, and what a consumer should copy from this estate.
Delete your controllers and Swashbuckle goes blind. Convey rebuilds the OpenAPI document by hand from its endpoint registry - a document filter, a naming convention, and a few spec violations it hopes you won't notice.
Redis registered in nine services and read in one, discovery stacks in services that never call anyone, an outbox package referenced but never wired, and versions that float by construction - an inventory of everything Pacco wires up and never uses.
A refactoring.guru walk through Pacco's real lines - a flags-enum search that can never match, twin guards, a dead password check, mappers that return null, and an Id that is never assigned - each smell named and each paired with the technique that cures it.
Chronicle's persistence surface is two interfaces - a state repository and an append-only log - and the defaults behind AddChronicle() are two Lists. What the contracts really demand, why the in-memory implementations are sharper than they look, and how to write a provider that holds up.
The self-styled uber AI order maker resolves to FirstOrDefault behind an in-source confession, and its reservation heuristic structurally out-bids every earlier booking - the estate's data-science audit, written up as the short honest piece its eleven lines deserve.
OrderMaker drives a whole order through a Chronicle saga and reports its progress in a single RabbitMQ header - stamped on every publish, forwarded by seven copied MessageBrokers, read back by Operations, and backed by a saga store that forgets everything on restart.
Deliveries maps domain events into integration events that carry facts while Vehicles publishes bare ids straight from its handlers - two event philosophies in one estate, and a vehicle-to-resource mirror that syncs deletes but never creates.
Operations subscribes to eighty estate messages from one hand-maintained JSON file - a shadow copy of every contract in the system that nothing validates, with ghost entries nobody publishes and real rejections it never lists.
Orders and Parcels keep the estate's only cross-service contract honest with Pactify - a pact written to a relative path six directories above the repository, verified against a seeded Huge Weapon, and checked for shape only. Consumer-driven contracts with no broker, read from source.
Nine Pacco repositories run dotnet test against zero test projects and stay vacuously green, while the one repo with a real unit-integration-e2e-performance pyramid is the only one whose Travis config omits the test step.
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.
Pacco models aggregates-per-document honestly across ten Mongo databases, and then creates exactly one index in the whole estate - fire-and-forget, in a scope that has already been disposed - while natural-key scans sit on the message hot path.
The fair part of the ledger - how UseDispatcherEndpoints, self-identifying commands, afterDispatch hooks and snake_case conventions let every Pacco service put its whole HTTP surface in one readable file.
MessageBroker.cs exists in seven Pacco repositories and hashes identically once you substitute the service name - this part inventories the copied glue, finds the double registrations hiding in seventeen-call chains, and weighs copy-paste against a shared kernel.
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.
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.
Convey.WebApi.CQRS wires HTTP verbs straight to command and query dispatchers - one line per endpoint - and publishes your message catalog at /_contracts. A source read of the thinnest HTTP layer I've shipped to production.
