AspNetCore.Docs/aspnetcore/grpc/migration.md

title	author	description	monikerRange	ms.author	ms.date	no-loc	uid
Migrate gRPC from C-core to gRPC for .NET	jamesnk	Learn how to move an existing C-core based gRPC app to run on top of gRPC for .NET.	>= aspnetcore-3.0	jamesnk	01/18/2022	Home Privacy Kestrel appsettings.json ASP.NET Core Identity cookie Cookie Blazor Blazor Server Blazor WebAssembly Identity Let's Encrypt Razor SignalR	grpc/migration

Migrate gRPC from C-core to gRPC for .NET

Due to the implementation of the underlying stack, not all features work in the same way between C-core-based gRPC apps and gRPC for .NET. This document highlights the key differences for migrating between the two stacks.

[!IMPORTANT] gRPC C-core is in maintenance mode and will be deprecated in favor of gRPC for .NET. gRPC C-core is not recommended for new apps.

Platform support

gRPC C-core and gRPC for .NET have different platform support:

• gRPC C-core: A C++ gRPC implementation with its own TLS and HTTP/2 stacks. The Grpc.Core package is a .NET wrapper around gRPC C-core and contains a gRPC client and server. It supports .NET Framework, .NET Core, and .NET 5 or later.
• gRPC for .NET: Designed for .NET Core 3.x and .NET 5 or later. It uses TLS and HTTP/2 stacks built into modern .NET releases. The Grpc.AspNetCore package contains a gRPC server that is hosted in ASP.NET Core and requires .NET Core 3.x or .NET 5 or later. The Grpc.Net.Client package contains a gRPC client. The client in Grpc.Net.Client has limited support for .NET Framework using xref:System.Net.Http.WinHttpHandler.

For more information, see xref:grpc/supported-platforms.

gRPC service implementation lifetime

In the ASP.NET Core stack, gRPC services, by default, are created with a scoped lifetime. In contrast, gRPC C-core by default binds to a service with a singleton lifetime.

A scoped lifetime allows the service implementation to resolve other services with scoped lifetimes. For example, a scoped lifetime can also resolve DbContext from the DI container through constructor injection. Using scoped lifetime:

• A new instance of the service implementation is constructed for each request.
• It isn't possible to share state between requests via instance members on the implementation type.
• The expectation is to store shared states in a singleton service in the DI container. The stored shared states are resolved in the constructor of the gRPC service implementation.

For more information on service lifetimes, see xref:fundamentals/dependency-injection#service-lifetimes.

Add a singleton service

To facilitate the transition from a gRPC C-core implementation to ASP.NET Core, it's possible to change the service lifetime of the service implementation from scoped to singleton. This involves adding an instance of the service implementation to the DI container:

public void ConfigureServices(IServiceCollection services)
{
    services.AddGrpc();
    services.AddSingleton(new GreeterService());
}

However, a service implementation with a singleton lifetime is no longer able to resolve scoped services through constructor injection.

Configure gRPC services options

In C-core-based apps, settings such as grpc.max_receive_message_length and grpc.max_send_message_length are configured with ChannelOption when constructing the Server instance.

In ASP.NET Core, gRPC provides configuration through the GrpcServiceOptions type. For example, a gRPC service's the maximum incoming message size can be configured via AddGrpc. The following example changes the default MaxReceiveMessageSize of 4 MB to 16 MB:

public void ConfigureServices(IServiceCollection services)
{
    services.AddGrpc(options =>
    {
        options.MaxReceiveMessageSize = 16 * 1024 * 1024; // 16 MB
    });
}

For more information on configuration, see xref:grpc/configuration.

Logging

C-core-based apps rely on the GrpcEnvironment to configure the logger for debugging purposes. The ASP.NET Core stack provides this functionality through the Logging API. For example, a logger can be added to the gRPC service via constructor injection:

public class GreeterService : Greeter.GreeterBase
{
    public GreeterService(ILogger<GreeterService> logger)
    {
    }
}

For more information on gRPC logging and diagnostics, see xref:grpc/diagnostics.

HTTPS

::: moniker range=">= aspnetcore-5.0" C-core-based apps configure HTTPS through the Server.Ports property. A similar concept is used to configure servers in ASP.NET Core. For example, Kestrel uses endpoint configuration for this functionality. ::: moniker-end

::: moniker range="< aspnetcore-5.0" C-core-based apps configure HTTPS through the Server.Ports property. A similar concept is used to configure servers in ASP.NET Core. For example, Kestrel uses endpoint configuration for this functionality. ::: moniker-end

gRPC Interceptors vs Middleware

ASP.NET Core middleware offers similar functionalities compared to interceptors in C-core-based gRPC apps. ASP.NET Core middleware and interceptors are conceptually similar. Both:

• Are used to construct a pipeline that handles a gRPC request.
• Allow work to be performed before or after the next component in the pipeline.
• Provide access to HttpContext:
  • In middleware the HttpContext is a parameter.
  • In interceptors the HttpContext can be accessed using the ServerCallContext parameter with the ServerCallContext.GetHttpContext extension method. Note that this feature is specific to interceptors running in ASP.NET Core.

gRPC Interceptor differences from ASP.NET Core Middleware:

• Interceptors:
  • Operate on the gRPC layer of abstraction using the ServerCallContext.
  • Provide access to:
    • The deserialized message sent to a call.
    • The message being returned from the call before it is serialized.
  • Can catch and handle exceptions thrown from gRPC services.
• Middleware:
  • Runs before gRPC interceptors.
  • Operates on the underlying HTTP/2 messages.
  • Can only access bytes from the request and response streams.

Additional resources

• xref:grpc/index
• xref:grpc/basics
• xref:grpc/aspnetcore
• xref:tutorials/grpc/grpc-start