Examples

Complete SEA™ DSL examples for common use cases.

Example 1: E-Commerce Orders

@namespace "com.example.ecommerce"
@version "1.0.0"

// Entities
Entity "Customer" in ecommerce
Entity "Order" in ecommerce
Entity "Product" in ecommerce
Entity "Inventory" in ecommerce

// Resources
Resource "Money" USD in ecommerce
Resource "OrderItem" units in ecommerce

// Command Flows
Flow "PlaceOrder"
  @cqrs { "kind": "command" }
  @tx { "transactional": true }
  @idempotency { "enabled": true, "key": "orderId" }
from "Customer" to "Order" quantity 1

Flow "ProcessPayment"
  @cqrs { "kind": "command" }
  @tx { "transactional": true }
from "Customer" to "Inventory"

// Event Flows
Flow "OrderPlaced"
  @cqrs { "kind": "event" }
  @outbox { "mode": "required" }
from "Order" to "EventBus"

// Query Flows
Flow "GetOrderHistory"
  @cqrs { "kind": "query" }
  @read_model { "name": "OrderProjection" }
from "QueryService" to "ReadStore"

// Policies
Policy order_must_have_items
  per Constraint Obligation priority 10
  @rationale "Empty orders are invalid"
as: forall o in entities where o.name = "Order": (o.items > 0)

Policy no_negative_payment
  per Constraint Prohibition priority 10
as: forall f in flows where f.resource = "Money": (f.quantity >= 0)

// Metrics
Metric "daily_orders" as:
  count(o in entities over last 24 "hours" where o.name = "Order": 1)
  @window 24 "hours"
  @threshold 100

Example 2: Authentication

@namespace "com.example.auth"
@version "1.0.0"

// Entities
Entity "User" in auth
Entity "Session" in auth
Entity "TokenStore" in auth

// Resources
Resource "Token" units in auth
Resource "Credential" units in auth

// Roles
Role "Admin" in auth
Role "User" in auth

// Flows
Flow "Login"
  @cqrs { "kind": "command" }
  @tx { "transactional": true }
from "User" to "Session" quantity 1

Flow "IssueToken"
  @cqrs { "kind": "command" }
from "Session" to "TokenStore"

Flow "TokenIssued"
  @cqrs { "kind": "event" }
  @outbox { "mode": "required" }
from "TokenStore" to "EventBus"

Flow "ValidateToken"
  @cqrs { "kind": "query" }
from "Session" to "TokenStore"

// Policies
Policy single_active_session
  per Constraint Obligation priority 10
as: forall u in entities where u.name = "User":
    count(s in entities where s.name = "Session" and s.userId = u.id: 1) <= 1

Policy token_expiry
  per Constraint Obligation priority 10
as: forall t in resources where t.name = "Token": (t.expiresAt > now())

Example 3: Financial Transfers

@namespace "com.example.finance"
@version "1.0.0"

// Dimensions and Units
Dimension "Currency"
Unit "USD" of "Currency" factor 1 base "USD"
Unit "EUR" of "Currency" factor 0.92 base "USD"

// Entities
Entity "Account" in finance
Entity "Ledger" in finance
Entity "AuditLog" in finance

// Resources
Resource "Money" USD in finance

// Flows
Flow "Transfer"
  @cqrs { "kind": "command" }
  @tx { "transactional": true }
  @idempotency { "enabled": true, "key": "transferId" }
from "Account" to "Account"

Flow "TransferCompleted"
  @cqrs { "kind": "event" }
  @outbox { "mode": "required" }
from "Ledger" to "EventBus"

Flow "GetBalance"
  @cqrs { "kind": "query" }
  @read_model { "name": "AccountBalanceProjection" }
from "QueryService" to "Ledger"

// Relations
Relation "AccountDebited"
  subject: "Account"
  predicate: "was debited by"
  object: "Transfer"
  via: flow "Transfer"

// Policies
Policy no_overdraft
  per Constraint Prohibition priority 10
  @rationale "Account balance cannot go negative"
as: forall a in entities where a.name = "Account": (a.balance >= 0)

Policy transfer_audit
  per Constraint Obligation priority 10
as: forall t in flows where t.name = "Transfer":
    exists l in entities where l.name = "AuditLog": (l.transferId = t.id)

// Metrics
Metric "daily_volume" as:
  sum(t in flows over last 24 "hours" where t.name = "Transfer": t.amount)
  @unit "USD"
  @threshold 1000000

Example 4: Kernel (Shared Infrastructure)

@namespace "shared"
@version "1.0.0"

// Core infrastructure entities
Entity "CommandBus" in kernel
Entity "QueryBus" in kernel
Entity "EventBus" in kernel
Entity "UnitOfWork" in kernel
Entity "Repository" in kernel
Entity "OutboxPort" in kernel

// Resources
Resource "ExecuteCommand" units in kernel
Resource "ExecuteQuery" units in kernel
Resource "PublishEvent" units in kernel
Resource "ManageTransaction" units in kernel

// Flows
Flow "ExecuteCommand"
  @cqrs { "kind": "command" }
from "CommandBus" to "CommandBus" quantity 1

Flow "ExecuteQuery"
  @cqrs { "kind": "query" }
from "QueryBus" to "QueryBus" quantity 1

Flow "PublishEvent"
  @cqrs { "kind": "event" }
from "EventBus" to "EventBus" quantity 1

Flow "ManageTransaction"
  @cqrs { "kind": "command" }
from "UnitOfWork" to "UnitOfWork" quantity 1

// Architectural policy
Policy KernelIndependence
  per Constraint Obligation priority 100
  @rationale "Kernel must be runnable without shells (ADR-033)"
  @tags ["kernel", "architecture"]
as: count(entities) >= 6

Last Updated: January 2026