**Pre-requisites** 1. Install Dapr CLI 2. .NET 6 SDK installed. 3. Docker Desktop **Create a Web API Publish Service** - Create a ASP.Net Core Web API project with .Net 6.0 framework version. Say name of the project as _publisher_ - Add nuget package _Dapr.AspNetCore_ (I have used version 1.12.0) - Add a directory say _dapr-components_ into your project. Add file _pubsub.yaml_ into the folder, which should look as below ``` apiVersion: dapr.io/v1alpha1 kind: Component metadata: name: myapp-pubsub spec: type: pubsub.redis version: v1 metadata: - name: redisHost value: localhost:6379 - name: redisPassword value: "" scopes: - publisher - subscriber ``` - Add below line of code into your _program.cs_ ``` builder.Services.AddDaprClient(); ``` Your _program.cs_ should look as below ``` var builder = WebApplication.CreateBuilder(args); // Add services to the container. builder.Services.AddControllers(); // Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle builder.Services.AddEndpointsApiExplorer(); builder.Services.AddSwaggerGen(); builder.Services.AddDaprClient(); var app = builder.Build(); // Configure the HTTP request pipeline. if (app.Environment.IsDevelopment()) { app.UseSwagger(); app.UseSwaggerUI(); } app.UseHttpsRedirection(); app.UseAuthorization(); app.MapControllers(); app.Run(); ``` - Add a WebAPI controller, say it as _PublishController.cs_. The code looks as below ``` using Dapr.Client; using Microsoft.AspNetCore.Mvc; using System; namespace Publisher.Controllers { [Route("api/[controller]")] [ApiController] public class PublishController : ControllerBase { private readonly DaprClient daprClient; private readonly ILogger logger; public PublishController(DaprClient daprClient, ILogger logger) { this.daprClient = daprClient; this.logger = logger; } [HttpPost] public async Task Post([FromBody] string value) { await daprClient.PublishEventAsync("myapp-pubsub", "test-dapr-topic", $"{DateTime.Now} - {value}"); logger.LogInformation($"Published data at {DateTime.Now} - {value}"); } } } ``` **Create a Web API Subscribe Service** - Create a ASP.Net Core Web API project with .Net 6.0 framework version. Say name of the project as _subscriber_ - Add nuget package _Dapr.AspNetCore_ (I have used version 1.12.0) - Add a directory say _dapr-components_ into your project. Add file _pubsub.yaml_ into the folder, which should look as below ``` apiVersion: dapr.io/v1alpha1 kind: Component metadata: name: myapp-pubsub spec: type: pubsub.redis version: v1 metadata: - name: redisHost value: localhost:6379 - name: redisPassword value: "" scopes: - publisher - subscriber ``` - Add below two lines of code into your _program.cs_ ``` /* The call to UseCloudEvents adds CloudEvents middleware into to the * ASP.NET Core middleware pipeline. * This middleware will unwrap requests that use the CloudEvents structured * format, so the receiving method can read the event payload directly. */ app.UseCloudEvents(); /* The call to MapSubscribeHandler in the endpoint routing configuration * will add a Dapr subscribe endpoint to the application. * * This endpoint will respond to requests on /dapr/subscribe. * When this endpoint is called, it will automatically find all WebAPI * action methods decorated with the Topic attribute and instruct * Dapr to create subscriptions for them. */ app.MapSubscribeHandler(); ``` your _program.cs_ should look as follows ``` var builder = WebApplication.CreateBuilder(args); // Add services to the container. builder.Services.AddControllers(); // Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle builder.Services.AddEndpointsApiExplorer(); builder.Services.AddSwaggerGen(); var app = builder.Build(); // Configure the HTTP request pipeline. if (app.Environment.IsDevelopment()) { app.UseSwagger(); app.UseSwaggerUI(); } app.UseHttpsRedirection(); app.UseAuthorization(); app.UseCloudEvents(); app.MapSubscribeHandler(); app.MapControllers(); app.Run(); ``` - Add a WebAPI controller, say it as _SubscriberController.cs_. The code looks as below ``` using Dapr; using Microsoft.AspNetCore.Mvc; namespace Subscriber.Controllers { [ApiController] [Route("api/[controller]")] public class SubscriberController : ControllerBase { ILogger logger; public SubscriberController(ILogger logger) { this.logger = logger; } [Topic("myapp-pubsub", "test-dapr-topic")] [HttpPost("subscriber")] public IActionResult Post([FromBody] string value) { logger.LogInformation(value); return Ok(value); } } } ``` **Testing our web api's publish subscribe** - Open docker desktop - Use below command to run publisher `dapr run --app-id publisher --app-port --app-protocol https --dapr-http-port 3608 --resources-path dapr-components -- dotnet run` - Use below command to run subscriber `dapr run --app-id subscriber --app-port --app-protocol https --dapr-http-port 3610 --resources-path dapr-components -- dotnet run` - Test using postman. Hit publisher endpoint. You can see in the logs that publisher published message and subscriber received message ![Image that tested pubsub of dapr](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/u4so2zlev4gra283xip7.png) **Source code** [dapr-publisher](https://github.com/ashwingatadi/dapr-publisher) [dapr-subscriber](https://github.com/ashwingatadi/dapr-subscriber)

ashwingatadi

Dapr - Publish/Subscibe - Using Web APIs

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