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Add Envoy comparison (#17816)

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James Newton-King 2020-04-16 08:38:34 +12:00 committed by GitHub
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aspnetcore/grpc/browser.md
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@ -4,7 +4,7 @@ author: jamesnk
description: Learn how to configure gRPC services on ASP.NET Core to be callable from browser apps using gRPC-Web.
monikerRange: '>= aspnetcore-3.0'
ms.author: jamesnk
ms.date: 02/16/2020
ms.date: 04/15/2020
uid: grpc/browser
---
# Use gRPC in browser apps
@ -23,6 +23,15 @@ By [James Newton-King](https://twitter.com/jamesnk)
It is not possible to call a HTTP/2 gRPC service from a browser-based app. [gRPC-Web](https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-WEB.md) is a protocol that allows browser JavaScript and Blazor apps to call gRPC services. This article explains how to use gRPC-Web in .NET Core.
## gRPC-Web in ASP.NET Core vs. Envoy
There are two choices for how to add gRPC-Web to an ASP.NET Core app:
* Support gRPC-Web alongside gRPC HTTP/2 in ASP.NET Core. This option uses middleware provided by the `Grpc.AspNetCore.Web` package.
* Use the [Envoy proxy's](https://www.envoyproxy.io/) gRPC-Web support to translate gRPC-Web to gRPC HTTP/2. The translated call is then forwarded onto the ASP.NET Core app.
There are pros and cons to each approach. If you're already using Envoy as a proxy in your app's environment, it might make sense to also use it to provide gRPC-Web support. If you want a simple solution for gRPC-Web that only requires ASP.NET Core, `Grpc.AspNetCore.Web` is a good choice.
## Configure gRPC-Web in ASP.NET Core
gRPC services hosted in ASP.NET Core can be configured to support gRPC-Web alongside HTTP/2 gRPC. gRPC-Web does not require any changes to services. The only modification is startup configuration.
@ -94,7 +103,7 @@ The preceding code:
The `GrpcWebHandler` has the following configuration options when created:
* **InnerHandler**: The underlying <xref:System.Net.Http.HttpMessageHandler> that makes the gRPC HTTP request, for example, `HttpClientHandler`.
* **Mode**: An enumeration type that specifies whether the gRPC HTTP request request `Content-Type` is `application/grpc-web` or `application/grpc-web-text`.
* **Mode**: An enumeration type that specifies whether the gRPC HTTP request `Content-Type` is `application/grpc-web` or `application/grpc-web-text`.
* `GrpcWebMode.GrpcWeb` configures content to be sent without encoding. Default value.
* `GrpcWebMode.GrpcWebText` configures content to be base64 encoded. Required for server streaming calls in browsers.
* **HttpVersion**: HTTP protocol `Version` used to set [HttpRequestMessage.Version](xref:System.Net.Http.HttpRequestMessage.Version) on the underlying gRPC HTTP request. gRPC-Web doesn't require a specific version and doesn't override the default unless specified.