EventBus adapters

Using EventBus adapters

MemoryEventBusAdapter

To use the MemoryEventBusAdapter you only need to create instance of it.

import { MemoryEventBusAdapter } from "@daiso-tech/core/event-bus/memory-event-bus-adapter";

const eventBusAdapter = new MemoryEventBusAdapter();

You can also provide an EventEmitter that will be used for dispatching the events in memory:

import { MemoryEventBusAdapter } from "@daiso-tech/core/event-bus/memory-event-bus-adapter";
import { EventEmitter } from "node:events";

const eventEmitter = new EventEmitter<any>();
const eventBusAdapter = new MemoryEventBusAdapter(eventEmitter);

info

MemoryEventBusAdapter lets you test your app without external dependencies like Redis, ideal for local development, unit tests, integration tests and fast E2E test for the backend application.

RedisPubSubEventBusAdapter

To use the RedisPubSubEventBusAdapter, you'll need to:

1. Install the required dependency: ioredis package
2. Provide a string serializer (ISerde)

• We recommend using SuperJsonSerdeAdapter for this purpose

import { RedisPubSubEventBusAdapter } from "@daiso-tech/core/event-bus/redis-pub-sub-event-bus-adapter";
import { Serde } from "@daiso-tech/core/serde";
import { SuperJsonSerdeAdapter } from "@daiso-tech/core/serde/super-json-serde-adapter";
import Redis from "ioredis";

const client = new Redis("YOUR_REDIS_CONNECTION_STRING");
const serde = new Serde(new SuperJsonSerdeAdapter());
const eventBusAdapter = new RedisPubSubEventBusAdapter({
    client,
    serde,
});

NoOpEventBusAdapter

The NoOpEventBusAdapter is a no-operation implementation, it performs no actions when called.

import { NoOpEventBusAdapter } from "@daiso-tech/core/event-bus/no-op-event-bus-adapter";

const noEventBusAdapter = new NoOpEventBusAdapter();

info

The NoOpEventBusAdapter is useful when you want to mock out or disable your EventBus class.

Creating EventBus adapters

Implementing your custom IEventBusAdapter

In order to create an adapter you need to implement the IEventBusAdapter contract.

Testing your custom IEventBusAdapter

We provide a complete test suite to verify your event bus adapter implementation. Simply use the eventBusAdapterTestSuite function:

• Preconfigured Vitest test cases
• Standardized event bus behavior validation
• Common edge case coverage

Usage example:

// filename: MyEventBusAdapter.test.ts

import { describe, test, beforeEach, expect } from "vitest";
import { eventBusAdapterTestSuite } from "@daiso-tech/core/event-bus/test-utilities";
import { MyEventBusAdapter } from "./MyEventBusAdapter.js";

describe("class: MyEventBusAdapter", () => {
    eventBusAdapterTestSuite({
        createAdapter: () => new MyEventBusAdapter(),
        test,
        beforeEach,
        expect,
        describe,
    });
});

Implementing your custom IEventBus class

In some cases, you may need to implement a custom EventBus class to optimize performance for your specific technology stack. You can then directly implement the IEventBus contract.

Testing your custom IEventBus class

We provide a complete test suite to verify your custom event bus class implementation. Simply use the eventBusTestSuite function:

• Preconfigured Vitest test cases
• Standardized event bus behavior validation
• Common edge case coverage

Usage example:

// filename: MyEventBus.test.ts

import { describe, test, beforeEach, expect } from "vitest";
import { eventBusTestSuite } from "@daiso-tech/core/event-bus/test-utilities";
import { MyEventBus } from "./MyEventBus.js";

describe("class: EventBus", () => {
    eventBusTestSuite({
        test,
        expect,
        describe,
        beforeEach,
        createEventBus: () => new MyEventBus(),
    });
});

Further information

For further information refer to @daiso-tech/core/event-bus API docs.