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Configuration

All publication configuration can be accessed via the MessagingBusBuilder.Publications fluent API:

services.AddJustSaying(config =>
{
    config.Publications(x =>
    {
        // Configure publications here
    });
});

The Publications builder provides methods to define where and how messages are published in your messaging topology.

Publication Types​

Topic Publications (SNS)​

Topics enable a publish-subscribe pattern where multiple subscribers can receive the same message.

config.Publications(x =>
{
    // Managed topic (naming convention based)
    x.WithTopic<OrderPlacedEvent>();

    // Managed topic with configuration
    x.WithTopic<OrderReadyEvent>(cfg =>
    {
        cfg.WithTag("IsOrderEvent", "true");
    });

    // Existing topic by ARN
    x.WithTopicArn<OrderPlacedEvent>("arn:aws:sns:us-east-1:123456789012:my-topic");
});

Queue Publications (SQS)​

Queues enable point-to-point messaging where only one consumer processes each message.

config.Publications(x =>
{
    // Managed queue (naming convention based)
    x.WithQueue<ProcessPaymentCommand>();

    // Managed queue with configuration
    x.WithQueue<ProcessPaymentCommand>(cfg =>
    {
        cfg.WithQueueName("payment-processing-queue");
    });

    // Existing queue by URL
    x.WithQueueUrl<ProcessPaymentCommand>("https://sqs.us-east-1.amazonaws.com/123456789012/my-queue");
});

Choosing Between Topics and Queues​

Use topics when:

  • Multiple services need to react to the same event
  • You need a fan-out pattern
  • Publishing events that represent something that happened

Use queues when:

  • Only one consumer should process the message
  • You need point-to-point delivery
  • Publishing commands for a specific service

Available Methods​

Topic Methods​

  • WithTopic<T>() - Create/use a topic with name from naming convention
  • WithTopic<T>(Action<TopicPublicationBuilder<T>>) - Configure topic publication
  • WithTopicArn<T>(string) - Publish to existing topic by ARN

Queue Methods​

  • WithQueue<T>() - Create/use a queue with name from naming convention
  • WithQueue<T>(Action<QueuePublicationBuilder<T>>) - Configure queue publication
  • WithQueueArn<T>(string) - Publish to existing queue by ARN
  • WithQueueUrl<T>(string) - Publish to existing queue by URL
  • WithQueueUri<T>(Uri) - Publish to existing queue by URI

Further Reading​