ETDL — Event Tree Definition Language for VS Code

Reliability modeling for event-driven microservices, right in your editor. This extension brings syntax highlighting, live validation, and IEC 62502 / IEC 61025 event tree visualization for the Event Tree Definition Language (.etdl).

ETDL is a declarative, design-time DSL that models causal sequences as event trees (IEC 62502:2010) and failure probability as fault trees (IEC 61025:2006), resolved against AsyncAPI 3.0 contracts — and compiles to code.

Features

🎨 Syntax highlighting

A TextMate grammar overlays the YAML structure with ETDL-specific scopes:

Node types (barrier, operation, consequence)
Fault tree gates (AND, OR, NOT, XOR, VOTING)
Branch outcomes (SUCCESS, FAILURE)
ECEL condition expressions
JSON Pointer references (orders_api#/components/messages/OrderPlaced)
Retry/backoff policies, probabilities, failure rates

✅ Live validation

The embedded ETDL compiler (Rust → WASM, no CLI needed) validates your document on open, edit, and save:

Syntax errors — malformed YAML, missing required sections
Semantic errors — invalid probabilities, barrier branch sums ≠ 1.0, ECEL type errors (V-204), fault tree gate arity, unresolved references
Warnings — non-fatal suspicious patterns

Diagnostics appear in the Problems panel with squiggly underlines. Errors are prefixed with their diagnostic code (E-103, V-204, W-402, …).

📊 Event tree visualization

Render your event trees and fault trees as an interactive diagram:

Barriers as decision diamonds with branch probabilities and ECEL conditions
Operations as rectangles with retry policy, timeout, and failure probability source
Consequences as terminal shapes
Fault trees with top event, gates (AND/OR/NOT/XOR/VOTING), and basic-event probabilities
Zoom in/out, refresh, color-coded by node type

The panel updates live as you edit.

Usage

Open any .etdl file — highlighting activates automatically.
Validate on demand with Command Palette → "ETDL: Validate Document".
Visualize with Command Palette → "ETDL: Visualize Event Tree" or the diagram button in the editor title bar.

AsyncAPI imports

The validator resolves asyncapi_imports (JSON Pointer references into AsyncAPI 3.0 YAML/JSON files). Files referenced by your document are read from your workspace automatically.

Configuration

Setting	Default	Description
`etdl.validation.enable`	`true`	Enable live validation
`etdl.validation.debounce`	`500`	Debounce delay (ms) before revalidating after edits
`etdl.visualization.renderer`	`raaml`	Diagram renderer (`raaml` or `mermaid`)
`etdl.visualization.layoutDirection`	`auto`	Diagram layout (`auto`, `LR`, `TB`)
`etdl.visualization.colorScheme`	`current`	Color scheme (`current`, `theme`, `raaml`)

IntelliSense

The extension wires the compiler's WASM semantic endpoints into native VS Code providers:

Go to definition — jump from a next/onFailure/rootCause reference to its node.
Find references — all references to a node/gate/event.
Hover — semantic details at the cursor.
Outline — event trees, fault trees, nodes, gates, basic events.
Completion — ETDL keywords and values.
Format — canonical document formatting.
Diagnostics — errors/warnings navigate to the exact source location (span positions from the compiler).

Example

etdl: "1.0.0"
info:
  title: "Order Fulfillment"
  version: "2.0.0"
  domain: "FulfillmentContext"

eventTrees:
  OrderFulfillment:
    initiatingEvent:
      id: OrderPlacedTrigger
      message: "orders_api#/components/messages/OrderPlaced"
      next: InventoryCheckBarrier
    nodes:
      InventoryCheckBarrier:
        type: barrier
        branches:
          - outcome: SUCCESS
            condition: "message.payload.items[*].qty > 0"
            probability: 0.95
            next: ProcessPaymentOperation
          - outcome: FAILURE
            condition: "default"
            probability: 0.05
            next: OutOfStockConsequence

faultTrees:
  PaymentGatewayFailure:
    topEvent:
      id: PaymentCaptureFailed
      rootCause: GatewayUnavailableOrRejected
    gates:
      GatewayUnavailableOrRejected:
        type: OR
        inputs: [GatewayUnreachable, ChargeRejected]
    basicEvents:
      GatewayUnreachable:
        probability: 0.008
      ChargeRejected:
        failureRate: 0.00021
        missionTime: 24

Development

The extension bundles etdl-wasm (the ETDL validator compiled to WebAssembly) in pkg/. The pkg/ files are committed, so a fresh checkout works out of the box. To rebuild them from source:

# 1. Rebuild the WASM validation engine
#    (clones the ETDL compiler repo, builds etdl-wasm, copies bindings into ./pkg)
bash scripts/build-wasm.sh

# 2. Compile TypeScript
npm install
npm run compile

# 3. Run unit tests (no GUI required)
npm run test:unit

# 4. Package a .vsix
npm run package

Requirements for step 1: Rust with the wasm32-unknown-unknown target and wasm-bindgen-cli (see scripts/build-wasm.sh).

License

Apache 2.0 — see LICENSE.

ETDL — Event Tree Definition Language

ETDL