Tutorial: the pet store

The pet store is the YAPS shop of the Java EE 7 sample (agoncal-application-petstore-ee7), rebuilt as ElastiCORE 3.0 + Spring Boot 4, hexagonal Java. It is a sample module of the ElastiCORE repository - generated, compiled and run on every generator change - and the public demo.

Try it	petstore.elasticore.io - sign in as user / user, or as the administrator xsko / xsko. The data resets when the server restarts
The source	elasticore-project/elasticore-sample-petstore
The DSL	src/main/resources/blueprint/petstore/ - env.yml, model/entity.yml, enum.yml, dto.yml, metrics.yml
API docs	/swagger-ui.html
The DSL next to the code	/dsl-guide.html ("DSL Guide" in the shop's header) - per business area: the rule, the DSL, the answers checked, what was hand-written, what the DSL cannot do

What the DSL says

Business rule	DSL
anyone browses the catalog, only the administrator edits it	@access(read=public)
an order is the signed-in customer's; reading and cancelling it are theirs, shipping the administrator's	@owner(customerId) @access(read=owner, create=user, cancel=owner)
a customer cannot make themselves an administrator	role: UserRole @access(admin)
passwords as hashes only; sign-in	password: string(255)! @password, login: ... @login, @signin
an order is placed, then shipped or cancelled; a shipped order cannot be cancelled	states: status: { initial: PLACED, ship: PLACED -> SHIPPED, cancel: PLACED -> CANCELLED }
a line's price is the price when ordered	unitCost: money(10.2) @snapshot(item.unitCost)
subtotals and the total	@compute(unitCost * quantity), @compute(sum(lines.subTotal))
the card number is never answered; an address's required fields answer 400	the value objects' @writeonly and !
a home address and a card are required	homeAddress: Address! @Embedded, creditCard: CreditCard! @Embedded

What was written by hand

File	What
domain/model/PurchaseOrder.java	the VAT and discount policy (from settings), the home address as the default delivery address
application/PurchaseOrderService.java	the policy values injected; place() when an order is first saved
adapter/in/web/shop/AccountController.java	sign up and be signed in at once (sign-in, sign-out and me are generated)
DemoAccounts.java, PetstoreApplication.java	the demo accounts, two beans

Everything else - entities, DTOs, mapper, repositories, services, controllers, access checks, state transitions, price calculation, the TypeScript client - is generated. The screen (web/src) uses the generated client's labels (OrderStatusLabel), validation (validateAddress), server errors (ApiError.fieldErrors) and button checks (canCancel).

Running it

From a clone of the ElastiCORE repository:

./gradlew :elasticore-project:elasticore-sample-petstore:test       # MockMvc flow tests
./gradlew :elasticore-project:elasticore-sample-petstore:webBuild   # the screen (Node.js needed)
./gradlew :elasticore-project:elasticore-sample-petstore:run        # http://localhost:8080

Locally the demo accounts are user / user and admin / admin (petstore.demo-accounts=false turns them off). The database is an in-memory H2, filled from data.sql at start-up.

The steps

1. The catalog - categories, products, items: public reading, search, sorting, money with a rule.
2. Customers who sign in - value objects, @password, @signin, a role only the administrator sets, sign-up.
3. Orders - the lifecycle, prices kept and summed, the shop's own policy.
4. The back office, events, metrics and messages - shipping, the events, the measures for BI, Korean error messages, the screen.
5. Evolving a generated project - a change request on a finished shop: stock, reviews, a courier API, BI measures - measured with Claude Code and the agent kit.

The build file of the sample, abridged:

build.gradle (elasticore-sample-petstore)

elasticore {
	architecture = 'hexagonal'
	language = 'java'
	// Read off the Spring Boot Gradle plugin in a project; this build's
	// Gradle predates the Boot 4 plugin, so it is said here.
	springBoot = '4'
	// The model as an Apache Ossie semantic model too: blueprint/semantic_model.yml
	rules = ['ossie-export']
}