@lafken/queue

@lafken/queue simplifies the creation and management of Amazon SQS queues and their integration with AWS Lambda. It provides decorators to define Standard and FIFO queues, configure their properties, and map message attributes and body content directly to your handler parameters.

Installation

npm install @lafken/queue

Configuration

Add the QueueResolver from the @lafken/queue/resolver library to your application configuration.

import { QueueResolver } from '@lafken/queue/resolver';

createApp({
  name: 'awesome-app',
  resolvers: [
    new QueueResolver(),
  ],
  // ...
});

@Queue()
class GreetingQueue {
  // ...
}

const greetingModule = createModule({
  name: 'greeting',
  resources: [
    GreetingQueue
  ]
});

Features

Defining a Queue Resource

Use the @Queue decorator to define a class that contains queue-processing methods.

import { Queue, Standard, Fifo } from '@lafken/queue';

@Queue()
export class NotificationService {
  // ... queue handlers
}

Standard Queues

Use the @Standard decorator to define a handler for a specific Standard SQS queue. You can configure properties such as visibility timeout, delivery delay, and batch size.

@Standard({
  queueName: 'emails',
  visibilityTimeout: 30,
  batchSize: 10,
})
sendEmail(@Event() event: SQSEvent) {
  // Process messages
}

FIFO Queues

Use the @Fifo decorator for FIFO (First-In-First-Out) queues. This ensures that the message order is preserved. You can enable content-based deduplication.

@Fifo({
  queueName: 'orders.fifo',
  contentBasedDeduplication: true,
})
processOrder(@Event() event: SQSEvent) {
  // Process ordered messages
}

Message Handling & Parameter Mapping

@lafken/queue allows you to extract specific data from the SQS message directly into your method parameters using @Param and @Payload.

Accessing Message Body Fields

You can parse the message body (if it's JSON) and inject specific fields.

@Standard({ queueName: 'registrations' })
registerUser(
  @Param({ source: 'body', parse: true, name: 'userId' }) userId: string,
  @Param({ source: 'body', parse: true, name: 'email' }) email: string
) {
  console.log(`Registering user ${userId} with email ${email}`);
}

Accessing Message Attributes

You can also access SQS Message Attributes.

@Standard({ queueName: 'logging' })
logMessage(
  @Param({ source: 'attribute', name: 'TraceId' }) traceId: string,
  @Event() event: any
) {
  // ...
}

Using Payload DTOs

You can use the @Payload decorator to map the entire message body to a typed object.

class UserDto {
  userId: string;
  email: string;
}

@Standard({ queueName: 'users' })
updateUser(@Payload() user: UserDto) {
  // user is fully typed and parsed from the message body
}