@saga-bus/transport-inmemory

In-memory transport implementation for testing and development.

Installation

pnpm add @saga-bus/transport-inmemory

Usage

import { InMemoryTransport } from "@saga-bus/transport-inmemory";
import { createBus } from "@saga-bus/core";

const transport = new InMemoryTransport({
  defaultConcurrency: 10,
});

const bus = createBus({
  transport,
  sagas: [...],
});

Features

• Zero external dependencies
• Configurable concurrency via semaphore
• Synchronous message delivery (great for tests)
• No network overhead

Configuration

| Option | Type | Default | Description | |--------|------|---------|-------------| | defaultConcurrency | number | 10 | Max concurrent handlers |

When to Use

Use for:

• Unit and integration tests
• Local development
• Prototyping and demos

Do not use for:

• Production deployments
• Distributed systems
• Multi-process applications

Testing Tips

The in-memory transport processes messages synchronously within the same process, making it ideal for testing:

import { TestHarness } from "@saga-bus/test";
import { InMemoryTransport } from "@saga-bus/transport-inmemory";

// TestHarness uses InMemoryTransport internally
const harness = await TestHarness.create({
  sagas: [{ definition: mySaga, store }],
});

// Messages are processed immediately
await harness.publish({ type: "OrderSubmitted", orderId: "123" });
await harness.waitForIdle();

// State is immediately available
const state = await harness.getSagaState("OrderSaga", "123");

Limitations

• Single process only: Messages are not shared between processes
• No persistence: Messages are lost if not consumed
• No ordering guarantees: Unlike production transports with FIFO support

For production, use @saga-bus/transport-rabbitmq, @saga-bus/transport-sqs, or @saga-bus/transport-kafka.

License

MIT