NServiceBus Full Duplex With LocalStack SQS and SNS

This is a follow up post to NServiceBus Full Duplex With LocalStack SQS and InMemory Persistence, this is a repurposed NServiceBus Full Duplex using SQS and SNS transport instead of using InMemory Persistence.

NServiceBus

NServiceBus is a service bus implementation for .NET. As a developer, it helps you create decoupled applications that are easier to maintain, extend and scale horizontally.

LocalStack

LocalStack is a fully funcational local AWS cloud stack, it provides an easy to use test duoble for developing cloud applications targeting AWS.

Components

The application consists of following components

Shared.Core

Common library with common message types that are exchanged between Client and Server. It also contains a POCO to load configuration from appsettings.

Api.Core

ASP.NET Core 3.1 WebApi application, this acts as NServiceBus client endpoint and sends messages to server. The code to send messages is in MessagesController.cs. It also implements a MessageHandler for DataResponseMessage to receive reply from server.

Server.Core

ASP.NET Core 3.1 console application, this acts as NServiceBus server endpoint. It implements message handler for RequestDataMessage, that handler is invoked by NServiceBus dispatcher when a message arrives in this endpoint’s queue.

Run Sample With LocalStack

Configuration to run with LocalStack

The magic happens in NServiceBusService.cs file in both Api.Core and Server.Core projects in ConfigureEndpoint method. We create an instance of AmazonSQSConfig and set its ServiceURL property if it is set in application configuration.

var amazonSqsConfig = new AmazonSQSConfig();
if (!string.IsNullOrEmpty(this.nServiceBusOptions.SqsServiceUrlOverride))
{
    amazonSqsConfig.ServiceURL = this.nServiceBusOptions.SqsServiceUrlOverride;
}

We use ClientFactory to create AmazonSQSClient with our configuration.

var transport = endpointConfiguration.UseTransport<SqsTransport>();
transport.ClientFactory(() => new AmazonSQSClient(
    new AnonymousAWSCredentials(),
    amazonSqsConfig));

For SNS, we create an instance of AmazonSimpleNotificationServiceConfig and set its ServiceURL property if it is set in application configuration.

var amazonSimpleNotificationServiceConfig = new AmazonSimpleNotificationServiceConfig();
if (!string.IsNullOrEmpty(this.nServiceBusOptions.SnsServiceUrlOverride))
{
    amazonSimpleNotificationServiceConfig.ServiceURL = this.nServiceBusOptions.SnsServiceUrlOverride;
}

We then use ClientFactory to create AmazonSimpleNotificationServiceClient with our configuration.

transport.ClientFactory(() => new AmazonSimpleNotificationServiceClient(
    new AnonymousAWSCredentials(),
    amazonSimpleNotificationServiceConfig));

For S3 storage for large messages, we create an instance of AmazonS3Config by setting ForcePathStyle property to true. This setting is needed as by default the client expects to append the bucket name to the domain name in order to access the bucket, and that would fail to reach our local S3 service running in LocalStack.

var amazonS3Config = new AmazonS3Config
{
    ForcePathStyle = true,
};
if (!string.IsNullOrEmpty(this.nServiceBusOptions.S3ServiceUrlOverride))
{
    amazonS3Config.ServiceURL = this.nServiceBusOptions.S3ServiceUrlOverride;
}

We use ClientFactory to use our configuration.

var s3Configuration = transport.S3("bucketname", "Samples-FullDuplex-Client");
s3Configuration.ClientFactory(() => new AmazonS3Client(
    new AnonymousAWSCredentials(),
    amazonS3Config));

Running the sample

Execute following on a powershell terminal to start up LocalStack and setup sqs queues required to run the sampel

./dev-env.ps1 start

Now you can run both Api.Core and Server.Core by following 1 of the below

• In Visual Studio by starting multiple projects
• In Visual Studio by starting docker-compose.dcproj
• From terminal, by using docker-compose up command

In all 3 cases you should have both applications running and you can open a browser, navigate to Api.Core url and can send messages to Server.Core.

TL;DR

Complete code for the sample with all the changes to run it against LocalStack container can be found in GitHub Repository Branch.

References

In no particular order
NServiceBus
LocalStack
NServiceBus Full Duplex Sample
And many more