AWS Messaging Framework Design

[ashovlin]

Context: The AWS .NET team is exploring creating an AWS native framework that simplifies development of .NET message processing applications using AWS services. This PR is to collect feedback on the design document. You can also read the rendered view.

The purpose of the framework would be to reduce the amount of boiler-plate code developers need to write. The primary responsibilities of the proposed framework are:

• Handling the message routing - In a publisher, the framework will handle routing the messages to the correct queue/topic/eventbus. In a consumer process, it will route the particular message type to the appropriate business logic.
• Handling the overall message lifecycle - The framework will handle serializing/deserializing the message to .NET objects, keeping track of the message visibility while it is being processed, and deleting the message when completed.

Here is an example showing a sample publisher and handler for a hypothetical OrderInfo message.

Sample publisher:

[ApiController]
[Route("[controller]")]
public class OrderController : ControllerBase
{
    // See later in the design for how this was configured and mapped to the queue
    private readonly IMessagePublisher _publisher;

    public OrderController(IMessagePublisher publisher)
    {
        _publisher = publisher;
    }

    [HttpPost]
    public async Task Post([FromBody] OrderInfo orderInfo)
    {
        // Add internal metadata to the OrderInfo object 
        // we received, or any other business logic
        orderInfo.OrderTime = DateTime.UtcNow;
        orderInfo.OrderStatus = OrderStatus.Recieved;

        // The updated OrderInfo object will also be serialized as the SQS message
        await _publisher.PublishAsync(orderInfo);
    }
}

Sample handler:

// See later in the design for how this was configured and mapped to the queue
public class OrderInfoHandler : IMessageHandler<OrderInfo>
{
    public async Task<MessageStatus> HandleAsync(MessageEnvelope<OrderReceived> message, CancellationToken cancellationToken = default(CancellationToken))
    {
        // Here we're reading from the message within the metadata envelope
        var productId = message.Message.ProductId;
        
        // Here we can do our business logic based on what is in the message
        await UpdateInventory(productId);
        await PrintShippingLabel(productId, message.Message.CustomerId);

        // Indicate that OrderInfo has been processed successfully
        return MessageStatus.Success;
    }
}

On either this PR or on specific section(s) of the design, please comment with:

• What are your thoughts and feedback on the proposed framework design?
• What are your thoughts on the initial MVP scope?
• Which AWS messaging services do you use?
  • Amazon SQS
  • Amazon SNS
  • Amazon EventBridge
  • Amazon Kinesis
  • Amazon MQ
  • Other (specify which ones) By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.