Examples

Complete reference

A language reference with all four workflows, ownership, an external system, a chapter, and a hotspot. The name describes syntax coverage, not business completeness.

state_changestate_viewautomationtranslation

The rendered canvas

Generated with emhcl diagram examples/complete.em.hcl. Use the view switcher for Model, Compact, Storming, and Context Map. Click a slice to view its scenarios. The pet clinic folder model splits this model into seven files.

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The source

Source file: examples/complete.em.hcl.

# Complete executable reference for Event Modeling HCL with bounded contexts. team "clinic_team" { title = "Clinic team" } system "partner_system" { title = "Partner system" external = true } actor "clinic_staff" { title = "Clinic staff" auth_required = true } bounded_context "clinic" { title = "Clinic" description = "Pet clinic operations and records." owner = team.clinic_team aggregate "pet" { title = "Pet" description = "A registered animal patient." } aggregate "owner" { title = "Owner" } field_type "pet_id" { cardinality = "Single" type = "UUID" id_attribute = true example = "07917485-4a6b-4e4e-8920-92ce6062a129" } field_type "pet_name" { mapping = "pet.name" schema = "PetName" type = "String" generated = false id_attribute = false optional = false pii = true technical_attribute = false example = "Mochi" } field_type "vaccinated" { type = "Boolean" example = true } field_type "weight" { type = "Double" example = 4.2 } field_type "fee" { type = "Decimal" example = 12.50 } field_type "microchip" { type = "Long" example = 1234567890 } field_type "birth_date" { type = "Date" example = "2020-01-12" } field_type "registered_at" { type = "DateTime" example = "2025-01-12T10:30:00Z" } field_type "pet_profile" { cardinality = "List" type = "Custom" example = [{ id = "07917485-4a6b-4e4e-8920-92ce6062a129" name = "Mochi" }] subfield "id" { type = "UUID" id_attribute = true } subfield "name" { type = "String" } } event "pet_registered" { title = "Pet Registered" description = "Records that a pet was registered." group_id = "registration" tags = ["event", "pet"] aggregate = aggregate.pet aggregate_dependencies = [aggregate.owner] service = null list_element = false prototype = { topic = "clinic.pet_registered" } sketched = false field "pet_id" { type = field_type.pet_id } field "pet_name" { type = field_type.pet_name } field "registered_at" { type = field_type.registered_at } } event "external_pet_imported" { field "pet_id" { type = field_type.pet_id } } event "owner_registered" { } } bounded_context "partner" { title = "Partner" owner = system.partner_system external = true event "pet_received" { title = "Pet Received" field "pet_id" { type = field_type.clinic.pet_id } } } state_change "register_pet" { description = "Register a new pet for an owner." owner = bounded_context.clinic status = "created" screen "pet_screen" { title = "Pet screen" actor = actor.clinic_staff fields = [field_type.clinic.pet_name] to = [command.register_pet_command] field "pet_id" { } } screen_image "pet_form" { title = "Pet form" url = "https://example.test/pet-form.png" } command "register_pet_command" { title = "Register pet" description = "Records a pet." group_id = "registration" tags = ["write", "pet"] aggregate = aggregate.clinic.pet aggregate_dependencies = [aggregate.clinic.owner] api_endpoint = "POST /pets" service = null creates_aggregate = true triggers = ["submit"] list_element = false prototype = { route = "/pets", method = "POST" } sketched = false to = [event.clinic.pet_registered] field "pet_id" { type = field_type.clinic.pet_id } field "pet_name" { type = field_type.clinic.pet_name } field "request_id" { type = "UUID" technical_attribute = true } } table "pets" { title = "Pets" field "pet_id" { type = field_type.clinic.pet_id } } scenario "register_pet_specification" { title = "Register a pet" given { title = "Owner exists" tags = ["setup"] examples = [{ owner_id = 9 }] expect_empty_list = false event = event.clinic.owner_registered } when { title = "Register pet" command = command.register_pet_command field "pet_name" { type = field_type.clinic.pet_name } } then { title = "Pet registered" event = event.clinic.pet_registered } then { title = "Validation error" expect_empty_list = true error = "Pet registration is invalid" } comment { description = "The owner relationship is assumed to exist." } } } state_view "pet_directory" { title = "Pet directory" status = "done" readmodel "pet_summary" { title = "Pet summary" question = "Which pets are registered?" from = [event.clinic.pet_registered] to = [screen.pet_summary_screen] field "pet_profile" { type = field_type.clinic.pet_profile } } screen "pet_summary_screen" { title = "Pet summary screen" actor = actor.clinic_staff } } automation "notify_owner" { title = "Notify owner" status = "in_progress" readmodel "pets_needing_notification" { title = "Pets needing notification" question = "Which pets require an owner notification?" from = [event.clinic.pet_registered] to = [processor.pet_notification] } processor "pet_notification" { title = "Pet notification" to = [command.send_owner_notification] } command "send_owner_notification" { title = "Send owner notification" aggregate = aggregate.clinic.owner to = [event.clinic.external_pet_imported] } } translation "import_partner_pet" { title = "Import partner pet" description = "Translate the partner contract into the clinic language." processor "translate_pet" { title = "Translate partner pet" from = [event.partner.pet_received] to = [command.import_pet] } command "import_pet" { title = "Import pet" to = [event.clinic.external_pet_imported] } } chapter "registration" { title = "Registration" workflows = [workflow.register_pet, workflow.pet_directory, workflow.notify_owner, workflow.import_partner_pet] } hotspot "notification_channel" { status = "open" question = "Which notification channel should be used?" on = processor.notify_owner.pet_notification }