MediatR-RPC
MediatR-RPC is an extension library for MediatR which aims automatically expose endpoints for corresponding Requests objects. Examples for an Http environment:
| Request | Http Endpoint |
|---|---|
| GetUser | /api/getuser |
| WriteLoan | /api/writeloan |
| ApprovePost | /api/approvepost |
Configuration
MediatR-RPC in its core is about matching a name with a corresponding request type that can be constructed and process by MediatR. This core feature is then applied on different hosting applications.
When configurating MediatR-RPC all configurations needs to be explicitly set. This way it is more clear for the reader what is going and what the expected behaviors are. Altought there are no implicit defaults there are some predefined configurations helpers available ready to use.
Getting started in ASP.NET Core
In ASP.NET Core MediatR-RPC will configure itself as an EndpointMiddleware with a single templated route, example:
https://localhost:44393/rpc/{requestName}
Install package from Nuget:
Install-Package MediatR.Extensions.RPC.AspNetCore
First register MediatR-RPC (and MediatR) when configurating the service by using the .AddMediatrRpc(...) extension method on the service collection:
public void ConfigureServices(IServiceCollection services)
{
// Additional configuration
var targetAssembly = this.GetType().Assembly;
services.AddMediatR(targetAssembly);
services.AddMediatrRpc(o =>
{
o.ScanRequests(targetAssembly);
o.UseExactRequestTypeNameMatchingConvention();
});
// Additional configuration
}In ASP.NET Core MediatR-RPC configures an EndpointMiddleware by applying the .MapRpc(...) extension method on the endpoints configuration:
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
// Additional configuration
app.UseEndpoints(endpoints =>
{
endpoints.MapControllers();
endpoints.MapRpc(o =>
{
var jsonSerializationOptions = new System.Text.Json.JsonSerializerOptions
{
PropertyNameCaseInsensitive = true
};
o.Path = "rpc";
o.UseSystemJsonForDeserializeBody(jsonSerializationOptions);
o.UseSystemJsonForOkOrNotFoundResult(jsonSerializationOptions);
});
});
// Additional configuration
}Getting started in Azure Functions
In Azure Function v3 MediatR-RPC will not be able to automatically add an Http triggered function, but it will instead provide a facade object for processing HttpRequests as Rpc calls.
First create an Azure Function v3 project with a Http trigger function, for example via Visual Studio.
Install package from Nuget:
Install-Package MediatR.Extensions.RPC.Azure.Functions
To be able to register MediatR-RPC the project needs to enable dependency injection by creating a FunctionStartup.
Once created, register MediatR-RPC (and MediatR) when configurating the service by using the .AddMediatrRpc(...) and .AddMediatrRpcHttp(...) extension methods on the service collection:
public void Configure(IWebJobsBuilder builder)
{
var targetAssembly = this.GetType().Assembly;
builder.Services
.AddMediatR(targetAssembly)
.AddMediatrRpc(o =>
{
o.ScanRequests(targetAssembly);
o.UseExactRequestTypeNameMatchingConvention();
})
.AddMediatrRpcHttp(o =>
{
o.UseNewtonsoftJsonForDeserializeBody();
o.UseOkorNotFoundActionResults();
});
}Configure the Http trigger function to be the RPC-endpoint by injecting the IRpcHttpFunction object and call it from the function:
public class RpcFunction
{
private readonly IRpcHttpFunction rpcFunction;
private readonly ILogger<RpcFunction> logger;
public RpcFunction(IRpcHttpFunction rpcFunction, ILogger<RpcFunction> logger)
{
this.rpcFunction = rpcFunction;
this.logger = logger;
}
[FunctionName("rpc")]
public async Task<IActionResult> Run(
[HttpTrigger(AuthorizationLevel.Function, "post", Route = "{requestName}")] HttpRequest req,
string requestName,
CancellationToken cancellationToken)
{
this.logger.LogDebug("Processing request: {RequestName}", requestName);
return await this.rpcFunction.ProcessHttpRequest(requestName, req, cancellationToken);
}
}
