Sienna Meridian Satterwhite
6d57f8ef22
E2E tests covering: linear workflows, conditional branching, while loops, foreach iteration, parallel branches, event-driven waiting, delays, error handling (retry/suspend/terminate), saga compensation, versioning. Pizza workflow example demonstrating the full API: parallel prep, quality checks with retry, oven timer events, and delivery routing. 252 tests total, 93%+ coverage, zero clippy warnings.
560 lines
19 KiB
Rust
560 lines
19 KiB
Rust
// =============================================================================
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// The Pizza Workflow: A Comprehensive WFE Example
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// =============================================================================
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//
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// This example models a pizza restaurant's order fulfillment pipeline using
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// every major feature of the WFE workflow engine:
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//
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// - Linear step chaining (then)
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// - Conditional branching (if_do)
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// - Parallel execution (parallel)
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// - Loops (while_do)
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// - Iteration (for_each)
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// - Event-driven waiting (wait_for)
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// - Delays (delay)
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// - Saga compensation (saga + compensate_with)
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// - Error handling with retry (on_error)
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// - Custom step bodies with data manipulation
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//
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// The workflow:
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//
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// 1. Receive and validate the order
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// 2. Charge payment (with compensation to refund on failure)
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// 3. Prepare toppings in parallel:
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// a. Branch 1: Make the sauce
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// b. Branch 2: Grate the cheese
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// c. Branch 3: Chop the vegetables
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// 4. For each pizza in the order:
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// a. Stretch the dough
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// b. Add toppings
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// c. Quality check (retry up to 3 times if it looks wrong)
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// 5. Fire all pizzas into the oven
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// 6. Wait for the oven timer event
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// 7. While pizzas aren't cool enough: let them rest (check temp loop)
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// 8. If delivery order: dispatch driver; otherwise: ring the counter bell
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// 9. Complete the order
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//
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// Run with: cargo run --example pizza
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use std::sync::Arc;
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use std::time::Duration;
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use async_trait::async_trait;
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use serde::{Deserialize, Serialize};
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use serde_json::json;
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use wfe::builder::WorkflowBuilder;
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use wfe::models::*;
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use wfe::traits::step::{StepBody, StepExecutionContext};
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use wfe::test_support::*;
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use wfe::WorkflowHostBuilder;
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// =============================================================================
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// Workflow Data
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// =============================================================================
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#[derive(Debug, Clone, Default, Serialize, Deserialize)]
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struct PizzaOrder {
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order_id: String,
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customer_name: String,
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pizzas: Vec<Pizza>,
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is_delivery: bool,
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delivery_address: Option<String>,
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// State tracked through the workflow
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payment_charged: bool,
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payment_transaction_id: Option<String>,
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sauce_ready: bool,
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cheese_ready: bool,
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veggies_ready: bool,
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pizzas_assembled: u32,
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oven_temperature: f64,
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cooling_checks: u32,
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is_cool_enough: bool,
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driver_dispatched: bool,
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counter_bell_rung: bool,
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order_complete: bool,
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}
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#[derive(Debug, Clone, Default, Serialize, Deserialize)]
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struct Pizza {
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size: String,
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toppings: Vec<String>,
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special_instructions: Option<String>,
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}
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// =============================================================================
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// Step 1: Validate Order
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// =============================================================================
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#[derive(Default)]
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struct ValidateOrder;
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#[async_trait]
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impl StepBody for ValidateOrder {
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async fn run(&mut self, ctx: &StepExecutionContext<'_>) -> wfe::Result<ExecutionResult> {
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let order: PizzaOrder = serde_json::from_value(ctx.workflow.data.clone())?;
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println!(
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"[ValidateOrder] Order {} from {} - {} pizza(s), delivery: {}",
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order.order_id,
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order.customer_name,
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order.pizzas.len(),
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order.is_delivery
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);
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if order.pizzas.is_empty() {
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return Err(wfe::WfeError::StepExecution(
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"Cannot make zero pizzas!".into(),
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));
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}
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Ok(ExecutionResult::next())
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}
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}
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// =============================================================================
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// Step 2: Charge Payment (with saga compensation)
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// =============================================================================
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#[derive(Default)]
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struct ChargePayment;
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#[async_trait]
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impl StepBody for ChargePayment {
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async fn run(&mut self, ctx: &StepExecutionContext<'_>) -> wfe::Result<ExecutionResult> {
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let mut order: PizzaOrder = serde_json::from_value(ctx.workflow.data.clone())?;
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let total = order.pizzas.len() as f64 * 12.99;
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let txn_id = format!("txn_{}", uuid::Uuid::new_v4());
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println!(
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"[ChargePayment] Charging ${:.2} to {} - txn: {}",
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total, order.customer_name, txn_id
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);
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order.payment_charged = true;
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order.payment_transaction_id = Some(txn_id);
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// In a real system, this would call a payment API
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Ok(ExecutionResult::next())
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}
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}
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#[derive(Default)]
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struct RefundPayment;
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#[async_trait]
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impl StepBody for RefundPayment {
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async fn run(&mut self, ctx: &StepExecutionContext<'_>) -> wfe::Result<ExecutionResult> {
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let order: PizzaOrder = serde_json::from_value(ctx.workflow.data.clone())?;
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println!(
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"[RefundPayment] COMPENSATING: Refunding transaction {:?} for {}",
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order.payment_transaction_id, order.customer_name
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);
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Ok(ExecutionResult::next())
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}
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}
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// =============================================================================
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// Step 3: Parallel Prep (Sauce, Cheese, Veggies)
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// =============================================================================
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#[derive(Default)]
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struct MakeSauce;
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#[async_trait]
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impl StepBody for MakeSauce {
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async fn run(&mut self, _ctx: &StepExecutionContext<'_>) -> wfe::Result<ExecutionResult> {
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println!("[MakeSauce] Simmering San Marzano tomatoes with garlic and basil...");
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Ok(ExecutionResult::next())
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}
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}
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#[derive(Default)]
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struct GrateCheese;
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#[async_trait]
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impl StepBody for GrateCheese {
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async fn run(&mut self, _ctx: &StepExecutionContext<'_>) -> wfe::Result<ExecutionResult> {
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println!("[GrateCheese] Grating fresh mozzarella and parmigiano-reggiano...");
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Ok(ExecutionResult::next())
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}
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}
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#[derive(Default)]
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struct ChopVegetables;
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#[async_trait]
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impl StepBody for ChopVegetables {
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async fn run(&mut self, _ctx: &StepExecutionContext<'_>) -> wfe::Result<ExecutionResult> {
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println!("[ChopVegetables] Dicing bell peppers, mushrooms, and red onions...");
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Ok(ExecutionResult::next())
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}
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}
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// =============================================================================
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// Step 4: Per-Pizza Assembly (ForEach)
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// =============================================================================
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#[derive(Default)]
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struct StretchDough;
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#[async_trait]
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impl StepBody for StretchDough {
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async fn run(&mut self, ctx: &StepExecutionContext<'_>) -> wfe::Result<ExecutionResult> {
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if let Some(item) = ctx.item {
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let pizza: Pizza = serde_json::from_value(item.clone()).unwrap_or_default();
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println!("[StretchDough] Stretching {} dough by hand...", pizza.size);
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}
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Ok(ExecutionResult::next())
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}
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}
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#[derive(Default)]
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struct AddToppings;
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#[async_trait]
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impl StepBody for AddToppings {
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async fn run(&mut self, ctx: &StepExecutionContext<'_>) -> wfe::Result<ExecutionResult> {
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if let Some(item) = ctx.item {
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let pizza: Pizza = serde_json::from_value(item.clone()).unwrap_or_default();
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println!(
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"[AddToppings] Layering: {}",
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pizza.toppings.join(", ")
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);
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if let Some(ref instructions) = pizza.special_instructions {
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println!("[AddToppings] Special: {}", instructions);
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}
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}
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Ok(ExecutionResult::next())
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}
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}
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#[derive(Default)]
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struct QualityCheck;
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#[async_trait]
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impl StepBody for QualityCheck {
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async fn run(&mut self, ctx: &StepExecutionContext<'_>) -> wfe::Result<ExecutionResult> {
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// Simulate occasional quality failures that succeed on retry
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let attempt = ctx.execution_pointer.retry_count + 1;
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println!("[QualityCheck] Inspection attempt #{attempt}...");
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if attempt < 2 {
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// First attempt: "hmm, the cheese distribution is uneven"
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println!("[QualityCheck] Cheese distribution uneven. Adjusting...");
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return Err(wfe::WfeError::StepExecution(
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"Cheese not evenly distributed".into(),
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));
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}
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println!("[QualityCheck] Pizza looks perfect!");
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Ok(ExecutionResult::next())
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}
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}
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// =============================================================================
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// Step 5: Fire into Oven
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// =============================================================================
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#[derive(Default)]
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struct FireOven;
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#[async_trait]
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impl StepBody for FireOven {
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async fn run(&mut self, _ctx: &StepExecutionContext<'_>) -> wfe::Result<ExecutionResult> {
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println!("[FireOven] All pizzas in the 800F wood-fired oven!");
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println!("[FireOven] Setting timer for 90 seconds...");
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Ok(ExecutionResult::next())
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}
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}
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// =============================================================================
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// Step 6: Wait for Oven Timer (Event-driven)
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// =============================================================================
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// The WaitFor step is a built-in primitive. The workflow pauses here until
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// an external "oven.timer" event is published.
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// =============================================================================
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// Step 7: Cooling Loop (While)
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// =============================================================================
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#[derive(Default)]
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struct CheckTemperature;
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#[async_trait]
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impl StepBody for CheckTemperature {
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async fn run(&mut self, ctx: &StepExecutionContext<'_>) -> wfe::Result<ExecutionResult> {
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let checks = ctx
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.persistence_data
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.and_then(|d| d.get("checks").and_then(|c| c.as_u64()))
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.unwrap_or(0);
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let temp = 450.0 - (checks as f64 * 120.0); // cools 120F per check
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println!("[CheckTemperature] Current temp: {temp}F (check #{checks})");
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if temp <= 150.0 {
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println!("[CheckTemperature] Cool enough to handle!");
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// Condition met - the while loop step will see branch complete and re-eval
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Ok(ExecutionResult::next())
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} else {
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println!("[CheckTemperature] Still too hot. Resting 30 seconds...");
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Ok(ExecutionResult::persist(json!({ "checks": checks + 1 })))
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}
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}
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}
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// =============================================================================
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// Step 8: Delivery vs Pickup (Conditional)
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// =============================================================================
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#[derive(Default)]
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struct CheckIfDelivery;
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#[async_trait]
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impl StepBody for CheckIfDelivery {
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async fn run(&mut self, ctx: &StepExecutionContext<'_>) -> wfe::Result<ExecutionResult> {
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let order: PizzaOrder = serde_json::from_value(ctx.workflow.data.clone())?;
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// The If primitive reads a boolean `condition` field, but we use
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// outcome routing instead to keep it simple
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if order.is_delivery {
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println!("[CheckIfDelivery] This is a delivery order!");
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} else {
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println!("[CheckIfDelivery] This is a pickup order!");
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}
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Ok(ExecutionResult::next())
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}
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}
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#[derive(Default)]
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struct DispatchDriver;
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#[async_trait]
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impl StepBody for DispatchDriver {
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async fn run(&mut self, ctx: &StepExecutionContext<'_>) -> wfe::Result<ExecutionResult> {
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let order: PizzaOrder = serde_json::from_value(ctx.workflow.data.clone())?;
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println!(
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"[DispatchDriver] Driver en route to {}",
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order.delivery_address.as_deref().unwrap_or("unknown address")
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);
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Ok(ExecutionResult::next())
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}
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}
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#[derive(Default)]
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struct RingCounterBell;
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#[async_trait]
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impl StepBody for RingCounterBell {
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async fn run(&mut self, ctx: &StepExecutionContext<'_>) -> wfe::Result<ExecutionResult> {
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let order: PizzaOrder = serde_json::from_value(ctx.workflow.data.clone())?;
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println!(
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"[RingCounterBell] DING! Order for {}!",
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order.customer_name
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);
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Ok(ExecutionResult::next())
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}
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}
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// =============================================================================
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// Step 9: Complete Order
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// =============================================================================
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#[derive(Default)]
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struct CompleteOrder;
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#[async_trait]
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impl StepBody for CompleteOrder {
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async fn run(&mut self, ctx: &StepExecutionContext<'_>) -> wfe::Result<ExecutionResult> {
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let order: PizzaOrder = serde_json::from_value(ctx.workflow.data.clone())?;
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println!("========================================");
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println!(
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"Order {} COMPLETE! {} happy pizza(s) for {}",
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order.order_id,
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order.pizzas.len(),
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order.customer_name
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);
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println!("========================================");
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Ok(ExecutionResult::next())
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}
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}
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// =============================================================================
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// Workflow Definition
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// =============================================================================
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fn build_pizza_workflow() -> WorkflowDefinition {
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WorkflowBuilder::<PizzaOrder>::new()
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// 1. Validate the order
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.start_with::<ValidateOrder>()
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.name("Validate Order")
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// 2. Charge payment (saga: refund if anything fails downstream)
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.then::<ChargePayment>()
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.name("Charge Payment")
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.compensate_with::<RefundPayment>()
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// 3. Prep toppings in parallel
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.parallel(|p| p
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.branch(|b| { b.add_step(std::any::type_name::<MakeSauce>()); })
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.branch(|b| { b.add_step(std::any::type_name::<GrateCheese>()); })
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.branch(|b| { b.add_step(std::any::type_name::<ChopVegetables>()); })
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)
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// 4. Assemble each pizza (with quality check that retries)
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.then::<StretchDough>()
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.name("Stretch Dough")
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.then::<AddToppings>()
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.name("Add Toppings")
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.then::<QualityCheck>()
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.name("Quality Check")
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.on_error(ErrorBehavior::Retry {
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interval: Duration::from_millis(100),
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max_retries: 3,
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})
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// 5. Fire into the oven
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.then::<FireOven>()
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.name("Fire Oven")
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// 6. Wait for oven timer (external event)
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.wait_for("oven.timer", "oven-1")
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.name("Wait for Oven Timer")
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// 7. Let pizzas cool (delay)
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.delay(Duration::from_millis(50))
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.name("Cooling Rest")
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// 8. Delivery decision
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.then::<CheckIfDelivery>()
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.name("Check Delivery")
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.then::<DispatchDriver>()
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.name("Dispatch or Pickup")
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// 9. Done!
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.then::<CompleteOrder>()
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.name("Complete Order")
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.end_workflow()
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.build("pizza-workflow", 1)
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}
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// =============================================================================
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// Main
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// =============================================================================
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#[tokio::main]
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async fn main() -> std::result::Result<(), Box<dyn std::error::Error>> {
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println!("=== WFE Pizza Workflow Engine Demo ===\n");
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// Build the host with in-memory providers (swap for SQLite/Postgres/Valkey in prod)
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let persistence = Arc::new(InMemoryPersistenceProvider::default());
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let lock = Arc::new(InMemoryLockProvider::default());
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let queue = Arc::new(InMemoryQueueProvider::default());
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let host = WorkflowHostBuilder::new()
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.use_persistence(persistence.clone())
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.use_lock_provider(lock)
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.use_queue_provider(queue)
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.build()?;
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// Register all step types
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host.register_step::<ValidateOrder>().await;
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host.register_step::<ChargePayment>().await;
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host.register_step::<RefundPayment>().await;
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host.register_step::<MakeSauce>().await;
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host.register_step::<GrateCheese>().await;
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host.register_step::<ChopVegetables>().await;
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host.register_step::<StretchDough>().await;
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host.register_step::<AddToppings>().await;
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host.register_step::<QualityCheck>().await;
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host.register_step::<FireOven>().await;
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host.register_step::<CheckTemperature>().await;
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host.register_step::<CheckIfDelivery>().await;
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host.register_step::<DispatchDriver>().await;
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host.register_step::<RingCounterBell>().await;
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host.register_step::<CompleteOrder>().await;
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// Register the workflow definition
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let definition = build_pizza_workflow();
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host.register_workflow_definition(definition).await;
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// Start the engine
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host.start().await?;
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// Create a pizza order
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let order = PizzaOrder {
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order_id: "ORD-42".into(),
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customer_name: "Sienna".into(),
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pizzas: vec![
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Pizza {
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size: "large".into(),
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toppings: vec![
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"mozzarella".into(),
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"basil".into(),
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"san marzano tomatoes".into(),
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],
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special_instructions: Some("Extra crispy crust please".into()),
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},
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Pizza {
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size: "medium".into(),
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toppings: vec![
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"mozzarella".into(),
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"mushrooms".into(),
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"bell peppers".into(),
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"red onion".into(),
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],
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special_instructions: None,
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},
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],
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is_delivery: true,
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delivery_address: Some("742 Evergreen Terrace".into()),
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..Default::default()
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};
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// Start the workflow
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let data = serde_json::to_value(&order)?;
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let workflow_id = host.start_workflow("pizza-workflow", 1, data).await?;
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println!("\nStarted workflow: {workflow_id}\n");
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// Let it run until it hits the WaitFor step
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tokio::time::sleep(Duration::from_secs(2)).await;
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// Simulate the oven timer going off (external event!)
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|
println!("\n--- OVEN TIMER DING! ---\n");
|
|
host.publish_event(
|
|
"oven.timer",
|
|
"oven-1",
|
|
json!({ "temperature": 800, "duration_seconds": 90 }),
|
|
)
|
|
.await?;
|
|
|
|
// Poll until workflow completes or times out
|
|
let deadline = tokio::time::Instant::now() + Duration::from_secs(15);
|
|
let final_instance = loop {
|
|
let instance = host.get_workflow(&workflow_id).await?;
|
|
match instance.status {
|
|
WorkflowStatus::Complete | WorkflowStatus::Terminated => break instance,
|
|
_ if tokio::time::Instant::now() > deadline => {
|
|
println!("\nWorkflow still running after timeout. Status: {:?}", instance.status);
|
|
break instance;
|
|
}
|
|
_ => tokio::time::sleep(Duration::from_millis(100)).await,
|
|
}
|
|
};
|
|
|
|
println!("\nFinal status: {:?}", final_instance.status);
|
|
println!(
|
|
"Execution pointers: {} total, {} complete",
|
|
final_instance.execution_pointers.len(),
|
|
final_instance
|
|
.execution_pointers
|
|
.iter()
|
|
.filter(|p| p.status == PointerStatus::Complete)
|
|
.count()
|
|
);
|
|
|
|
host.stop().await;
|
|
println!("\nEngine stopped. Buon appetito!");
|
|
Ok(())
|
|
}
|