Three Ages of a Domain Model
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.
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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.
Idempotency Aspired, Not Enforced
DShop runs competing consumers over an at-least-once bus with no message-id dedup, so a redelivered reservation decrements stock twice - the estate aspires to idempotency and enforces none of it. Part 9 of Nine Services and a Message Bus.
One Orchestrator Subscribes to Everything
Operations subscribes to every command and event in the estate by reflection and routes them through two open-generic handlers - a neat trick with one dead limb the wiring can never light. Part 8 of Nine Services and a Message Bus.
One Shop, Two Front Doors
DShop's gateway reads over HTTP and writes over a message bus - two dispatch mechanisms behind one controller. Reading it shows how a gateway can be a router and a publisher at the same time.
The Retry Path Nobody Took
A complete broker-requeue retry implementation sits in DShop.Common's subscriber, fully written and never called - and its comment explains exactly why.
Rejected Events — a Two-Lane Error Taxonomy
DShop.Common decides a message's fate from the type of exception a handler throws - domain failures become events, infrastructure failures get retried.
Swap the Dispatcher for a Bus
The monolith and the microservices share the same command names. Decomposition here was one substitution - resolve a local handler, or publish to a broker - and reading both dispatchers shows exactly what changes.
OrderCreated in Three Shapes
The same event is declared three times across DShop, and one copy quietly drops a field - here is the contract drift in the real source and the canonical-model cure that would have caught it. Part 3 of Nine Services and a Message Bus.
Command or Event, Enforced by Convention
In DShop.Common a command and an event are published by identical code - the difference between them is a marker interface and a promise nothing enforces.
Queue Names Are the Whole Topology
One naming class in DShop.Common decides every exchange, routing key and queue in the estate - the message topology is a string-formatting problem.
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.
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.