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Four Pacco services need customer data and no two agree on how to get it - Orders and Parcels keep id-only replicas fed by events, Availability phones home mid-command, and Pricing pulls the full details document to count one number. One upstream, three consistency stances, five representations of the same entity.
Inside the Customers service a registration completes - and the rest of the estate hears that a customer was created. Three lines of EventMapper perform the best ubiquitous-language translation in Pacco, sitting on top of a lifecycle state machine with one guarded transition and four administrative jumps.
Order.DeleteParcel raises a ParcelDeleted event and never removes the parcel from the set, while Parcels' cancel and delete handlers detach exactly one parcel of many. Two bounded contexts maintain the same association independently, both with bugs, and end up permanently disagreeing about a fact.
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.
Convey's IRejectedEvent gives Pacco an application-level negative acknowledgement - a rejected twin for every command. Reading the four exception-to-message mappers shows the pattern decaying in four different ways, from a failed reserve announced as a failed release to rejection classes nothing ever constructs.
Availability's ResourceReserved event carries no order id, no correlation id, no saga id - just a resource and a date. Orders finds the right order anyway, by treating (vehicleId, deliveryDate) as the correlation key, and the expropriation flow shows exactly when that key stops being unique.
Correlation ids and cascade archiving in ArchiveKit - how one Guid per save turns scattered archive rows into a reconstructable object graph, why cascade happens through the EF change tracker rather than the database, and two honest limits: a naive root heuristic and a CascadeArchive flag the interceptor doesn't read yet. Part 6 of the Archive-on-Delete with ArchiveKit series.
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.
Pacco's flagship flow reconstructed from source - a vehicle is assigned, a reservation lands, an order approves itself, and when a VIP bumps the booking the cancellation ripples through three services with no process manager in sight.
Every transition of Pacco's Order raises the same domain event - OrderStateChanged - and a mapper switches on aggregate status to mint five distinct integration events. A content-based router keyed on state, weighed honestly.
How Convey wraps every command and event handler with template-driven logging using one attribute, a Scrutor decoration — and a reflection trick against Scrutor itself that I admire and would never ship.
Availability's Resource aggregate enforces one real business rule - a higher-priority reservation evicts yours and announces it. The invariant, the struct value object behind it, and the day-integer it becomes on disk.
Lazy migration makes deploys instant but taxes every read of old data. VersionKit's backfill service rewrites stale payloads in scheduled batches until the store converges on the current version - in a host, or from a serverless function. Part 6 of the Entity Versioning with VersionKit series.
services.AddChronicle() registers sagas you never mentioned, and one ProcessAsync call can run five of them in parallel. Inside Chronicle's Scrutor scan, the seeker's dedupe trick, and the ref-counted lock that serializes each saga id.
Same framework, same four-project layout, three maturities - Parcels publishes from handlers, Orders raises events and maps them inline, Availability runs a full pipeline. The lineage made diffable.
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.
FastEndpoints binds a single request DTO from JSON, form, route, query, claims, headers, cookies and permissions - in that order, with compiled setters cached per DTO type. Reading the binder explains every binding surprise I have ever hit. Part 4 of FastEndpoints in Depth.
A retrospective on DShop.Common - the frozen shared-contracts tombstone, a release candidate pinned forever, and a concordance of what Convey kept, renamed, and fixed.
Tenants are data too. The tenant-management database is the one single-tenant database in the whole platform, and its five entities — Tenant, TenantConnection, TenantFeature, DatabaseGroup, TenantMigrationHistory — carry every decision the rest of the series depends on.
A retrospective on nine DShop services - the order aggregate and checkout saga that genuinely work, sitting next to the discount that only prints, the emails that never send, and a currency guard that guards nothing. Part 15 of Nine Services and a Message Bus.
Each concern in DShop.Common builds a throwaway DI container just to read config - nine per service, atop three coexisting container frameworks and a vendored config parser.
Above raw resolution sits a convention layer - an abstract endpoint base class that derives its Key Vault lookup key from its own type name, a template method separating the call from the interpretation, and a generic proxy that routes by name across every endpoint the DI container knows. Part 4 of Service Discovery Without a Service Mesh.
Nine DShop services ship a tests folder and only one of them tests anything - a census where five test projects cannot even see the code they claim to cover and the lone unit test asserts a thing that never happens. Part 14 of Nine Services and a Message Bus.
DShop.Common makes a stateless JWT revocable with a Redis deny-list and a per-request round-trip - plus an iat claim in milliseconds and two validators that disagree.
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.
