Configuring EventBus adapters

MemoryEventBusAdapter

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

./samples/memory-event-bus-adapter.ts

import { MemoryEventBusAdapter } from "eridu-tech/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:

./samples/memory-event-bus-adapter-with-emitter.ts

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

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

Pass any ITransactionHooks (like a TransactionContext, MultiTransactionHooks) as the transactionHooks setting to make the adapter transaction aware. Events dispatch immediately outside a transaction, and inside transaction events dispatch after commit:

./samples/transaction-context.ts

import { ExecutionContext } from "eridu-tech/execution-context";
import { AlsExecutionContextAdapter } from "eridu-tech/execution-context/als-execution-context-adapter";
import { contextToken } from "eridu-tech/execution-context/contracts";
import { TransactionContext } from "eridu-tech/transaction-context";
import { KyselyTransactionAdapter } from "eridu-tech/transaction-context/kysely-transaction-adapter";
import Sqlite from "better-sqlite3";
import { Kysely, SqliteDialect } from "kysely";

const database = new Kysely<any>({
    dialect: new SqliteDialect({
        database: new Sqlite("DATABASE_NAME.db"),
    }),
});

export const transactionContext = new TransactionContext<Kysely<any>>({
    // The token the active transaction is stored under
    token: contextToken("sqlite-transaction"),

    // You can choose the adapter to use
    adapter: new KyselyTransactionAdapter({ database }),

    // The execution context that tracks the active transaction across scopes
    executionContext: new ExecutionContext(new AlsExecutionContextAdapter()),
});

./samples/memory-event-bus-adapter-transaction-aware.ts

import { MemoryEventBusAdapter } from "eridu-tech/event-bus/memory-event-bus-adapter";
import { transactionContext } from "./transaction-context.js";

const eventBusAdapter = new MemoryEventBusAdapter({
    // Immediately outside a transaction, after commit inside transaction
    transactionHooks: transactionContext,
});

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

./samples/redis-pub-sub-event-bus-adapter.ts

import { RedisPubSubEventBusAdapter } from "eridu-tech/event-bus/redis-pub-sub-event-bus-adapter";
import { Serde } from "eridu-tech/serde";
import { SuperJsonSerdeAdapter } from "eridu-tech/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,
});

Pass any ITransactionHooks (like a TransactionContext, MultiTransactionHooks) as the transactionHooks setting to make the adapter transaction aware. Events dispatch immediately outside a transaction, and inside transaction events dispatch after commit:

./samples/redis-pub-sub-event-bus-adapter-transaction-aware.ts

import { RedisPubSubEventBusAdapter } from "eridu-tech/event-bus/redis-pub-sub-event-bus-adapter";
import { Serde } from "eridu-tech/serde";
import { SuperJsonSerdeAdapter } from "eridu-tech/serde/super-json-serde-adapter";
import { Redis } from "ioredis";
import { transactionContext } from "./transaction-context.js";

const client = new Redis("YOUR_REDIS_CONNECTION_STRING");
const serde = new Serde(new SuperJsonSerdeAdapter());
const eventBusAdapter = new RedisPubSubEventBusAdapter({
    client,
    serde,
    // Immediately outside a transaction, after commit inside transaction
    transactionHooks: transactionContext,
});

NoOpEventBusAdapter

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

./samples/no-op-event-bus-adapter.ts

import { NoOpEventBusAdapter } from "eridu-tech/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.

Further information

For further information refer to eridu-tech/event-bus API docs.