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JSON has become an essential part of virtually all modern .NET applications and in many cases even surpassed the usage of XML. However, .NET hasn't had a (great) built-in way to deal with JSON. Instead we've relied on Json.NET which continues to serve the .NET ecosystem well.
Moving forward, we plan on making some changes to our JSON support:
Below are more details around this plan.
The need for high-performance JSON APIs
The requirements for the .NET stack have changed a bit since the arrival of .NET Core. Historically, .NET has valued usability and convenience. With .NET Core, we've added a focus on performance, and we've made significant investments to serve high performance needs. And the improvements we made in the popular TechEmpower benchmark are a testament to that.
With .NET Core 2.1, we've added a brand new primitive called Span<T> that allows us to represent native memory and arrays in a uniform way. With this type, we've also added a set of parsing and encoding APIs that are much more memory efficient without having to resort to unsafe code.
Part of the work of minimizing allocations is to avoid having to transcode UTF-8 payloads into UTF-16 strings, purely for parsing reasons. Currently, Json.NET is implemented by reading UTF-16. We need the ability to read (and write) JSON documents directly in UTF-8 because most network protocols (including HTTP) use UTF-8.
During .NET Core 2.1 we've learned that updating our existing APIs to leverage
Based on these experiences we believe in order to support JSON parsing, we'll need to expose a new set of JSON APIs that are specifically geared for high-performance scenarios.
You might wonder why we can't just update Json.NET to include support for parsing JSON using
Move Json.NET integration into a separate NuGet package
Today, you cannot use ASP.NET Core without Json.NET because it is a dependency of ASP.NET Core itself. Over the years, we've received feedback that the dependency can conflict with other libraries that have their own dependency on a different version of Json.NET. In the past, we've considered addressing this issue by using a private copy of Json.NET in ASP.NET. However, this would create problems when developers want to configure Json.NET (for instance, in order to control how the serializer behaves when formatting JSON objects).
Moving forward we'd like to:
So the existing integration between ASP.NET Core and Json.NET will continue to be supported, but will be moving out of the platform and into a separate package. However, since the integration is then designed to sit on top of the platform, it will also allow customers to update Json.NET to later versions.
Furthermore, customers who need more performance can also choose to use the new JSON APIs, at the expense of the rich feature set that Json.NET offers.
For a discussion, please go to https://github.com/dotnet/corefx/issues/33115.