Juner.AspNetCore.Sequence 1.0.0

Juner.AspNetCore.Sequence

Streaming support for record‑oriented JSON formats (NDJSON, JSON Lines, JSON Sequence) in ASP.NET Core MVC and Minimal API.

This package integrates Juner.Sequence with ASP.NET Core, providing:

• Streaming input via SequenceInputFormatter and Sequence<T>
• Streaming output via JsonSequenceResult, JsonLineResult, NdJsonResult, and SequenceResult
• Natural Minimal API integration
• MVC integration through formatters and metadata
• OpenAPI (.NET 10+) support for streaming schemas
• Content negotiation for streaming formats

It enables true end‑to‑end streaming pipelines in ASP.NET Core without buffering entire payloads.

Installation

dotnet add package Juner.AspNetCore.Sequence

Quick Start

Minimal API — Streaming JSON Output

app.MapGet("/events", () =>
    TypedResults.JsonSequence(GetEvents()));

static async IAsyncEnumerable<Event> GetEvents()
{
    while (true)
    {
        yield return new Event { Message = "tick", Time = DateTime.UtcNow };
        await Task.Delay(1000);
    }
}

Minimal API — Streaming JSON Input

app.MapPost("/upload", async (Sequence<MyType> items) =>
{
    await foreach (var item in items)
        Console.WriteLine(item);
});

Sequence<T> is an ASP.NET Core–native type that represents a streaming JSON input,
allowing items to be consumed as they arrive without buffering.

Supported Streaming Formats

Streaming Output

The following return types are supported for streaming responses:

Minimal API Result Types

return TypedResults.JsonSequence(values);
return TypedResults.JsonLine(values);
return TypedResults.NdJson(values);
return TypedResults.Sequence(values); // content negotiation

MVC OutputFormatter

Streaming is enabled when the client sends:

• Accept: application/json-seq
• Accept: application/x-ndjson
• Accept: application/jsonl

Streaming Input

ASP.NET Core actions can accept the following types as streaming input:

Minimal API Example

app.MapPost("/items", async (Sequence<Item> items) =>
{
    await foreach (var item in items)
        Console.WriteLine(item);
});

MVC InputFormatter

Streaming is enabled for:

• application/json-seq
• application/x-ndjson
• application/jsonl

Content Negotiation

SequenceResult<T> automatically selects the best streaming format based on the client's Accept header.

return TypedResults.Sequence(values);

JSON Array (application/json)

JSON arrays are not true streaming formats, as they require full buffering.

SequenceResult<T> can return JSON arrays, but they are fully buffered.

For true streaming, use:

• JsonSequenceResult<T>
• JsonLineResult<T>
• NdJsonResult<T>

OpenAPI Integration (.NET 10+)

Enable OpenAPI support:

services.AddSequenceOpenApi();

Streaming endpoints are annotated with:

• x-streaming: true
• x-itemSchema: { ... }
• Correct content types per format

Both request and response schemas are generated accurately.

Architecture

graph TD;
    A[Juner.Sequence<br/>Core]
    B[Juner.Http.Sequence]
    C[Juner.AspNetCore.Sequence]

    A --> B
    B --> C

    C --> D[InputFormatter<br/>SequenceInputFormatter]
    C --> E[OutputFormatter<br/>JsonSequence / JsonLine / NdJson]
    C --> F[Result Types<br/>JsonSequenceResult / JsonLineResult / NdJsonResult / SequenceResult]
    C --> G[Sequence<T><br/>Minimal API Integration]
    C --> H[OpenAPI (.NET 10+)]

AOT Considerations

ASP.NET Core MVC formatters rely on:

• dynamic code generation
• reflection
• JsonSerializerOptions and TypeInfoResolver

Because of these framework‑level constraints,
MVC streaming (InputFormatter / OutputFormatter) is not AOT‑safe.

However:

✔ Minimal API is AOT‑friendly

When using only:

• Sequence<T> (for streaming input)
• JsonSequenceResult<T>, JsonLineResult<T>, NdJsonResult<T>, SequenceResult<T> (for streaming output)

no MVC formatters are involved, and
Minimal API streaming works under Native AOT.

Summary

Samples

This repository includes two complete samples:

• Minimal API JSON Sequence Streaming Sample
• MVC JSON Sequence Streaming Sample

Both demonstrate:

• Streaming output (JsonSequenceResult)
• Streaming input (Sequence<T>)
• Bidirectional streaming using fetch() with duplex: 'half'
• Browser‑side JSON Sequence parsing (json-seq-stream)
• OpenAPI (.NET 10+) integration

Minimal API Sample

Located at:

../samples/AspNetCore.Sequence/MinimalApiJsonSequenceStreamingSample.cs

MVC Sample

Located at:

../samples/AspNetCore.Sequence/MvcJsonSequenceStreamingSample.cs

License

MIT