entity-counter

Entity Counter Example

This example demonstrates a simple Counter entity using Durable Entities.

What are Durable Entities?

Durable Entities are stateful objects that can be addressed by a unique ID. They process operations one at a time, ensuring consistency without explicit locks.

Key Concepts

This example demonstrates:

• Defining an entity with TaskEntity<TState>
• Entity operations (add, get, reset)
• Signaling entities from a client (fire-and-forget)
• Getting entity state from a client

Prerequisites

You need a Durable Task-compatible backend. Choose one:

Option 1: DTS Emulator (Recommended for testing)

docker run --name dts-emulator -i -p 8080:8080 -d --rm mcr.microsoft.com/dts/dts-emulator:latest

Option 2: Local Sidecar

Install and run the Durable Task Sidecar or Dapr CLI on localhost:4001.

Running the Example

With DTS Emulator

npm run start:emulator

With Local Sidecar

npm run start

Expected Output

Connecting to endpoint: localhost:8080, taskHub: default
Worker started successfully

--- Signaling entity operations ---
Signaled: add(5)
Signaled: add(3)
Signaled: add(-2)

--- Getting entity state ---
Counter value: 6
Last modified: [timestamp]

--- Resetting counter ---
Signaled: reset()
Counter value after reset: 0

--- Cleaning up ---
Worker stopped