Dapr Pub-Sub with .NET Core Sample (without using Dapr Dotnet-SDK)

This sample includes 3 .NET Core WebApi as below:

1 publisher
- Example.Dapr.Publisher
2 subcribers:
- Example.Dapr.FirstSubscriber will subscribe on ProductCreated topic
- Example.Dapr.SecondSubscriber will subscribe on ProductCreated topic

Prerequisites

Install Docker for Desktop
Install Dapr Cli

How to deploy to Kubernetes

Please see the Guide

Run projects with Dapr Cli

Starting Publisher

cd .\source\Example.Dapr.Publisher\

dapr run --app-id example-publisher --app-port 5000 dotnet run

Starting FirstSubscriber

cd .\source\Example.Dapr.FirstSubscriber\

dapr run --app-id example-first-subscriber --app-port 5001 dotnet run

Starting SecondSubscriber

cd .\source\Example.Dapr.SecondSubscriber\

dapr run --app-id example-second-subscriber --app-port 5002 dotnet run

Use the CLI to Publish Messages to Subscribers

dapr publish --topic ProductCreated --payload "{ \"ProductId\": 1, \"Code\":\"this-is-a-test\" }"

Both subscribers which are example-first-subscriber & example-second-subscriber receive a message

Use Visual Studio Code and RestClient extension to publish the message

RestClient extension must be installed within Visual Studio Code
Open vscode-rest-test\create-product.http by Visual Studio Code; then click on Send Request and observe the log

Notes

For Subscribers

Since we subscribe on ProductCreated topic, hence we have to define the endpoint as below

[HttpPost("ProductCreated")]
public IActionResult SubscribeProductCreated(CloudEvent request)

Remember add CloudEventJsonInputFormatter

services
    .AddControllers(opts =>
    {
        opts.InputFormatters.Insert(0, new CloudEventJsonInputFormatter());
    })
    .AddJsonOptions(opts => opts.JsonSerializerOptions.PropertyNameCaseInsensitive = true);

Then expose to Dapr runtime by define the MapGet inside Startup.cs

app.UseEndpoints(endpoints =>
{
    endpoints.MapControllers();
    endpoints.MapGet("/dapr/subscribe", async context =>
    {
        var channels = new[] { "ProductCreated" };
        var toJson = JsonSerializer.Serialize(channels);
        context.Response.ContentType = "application/json";
        await context.Response.WriteAsync(toJson);
    });
});

For Publisher

First, we define the DaprPublisher as Http Client in Startup.cs

services
    .AddHttpClient<DaprPublisher>((provider, client) =>
    {
        var logger = provider.GetRequiredService<ILogger<Startup>>();

        var daprPort = Environment.GetEnvironmentVariable("DAPR_HTTP_PORT") ?? "3500";

        var baseAddress = $"http://localhost:{daprPort}";

        logger.LogInformation($"[{nameof(Startup)}] - Publish Address: {baseAddress}");

        client.BaseAddress = new Uri(baseAddress, UriKind.Absolute);
    });

Then, in order to publish the message to ProductCreated topic, we just simply make a POST request to http://localhost:{DAPR_HTTP_PORT}/v1.0/publish/ProductCreated. See the code at DaprPublisher.cs

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kimcuhoang/dnc-dapr-without-dotnet-sdk