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Send DELETE request when closing a Streamable HTTP session on the client (#501)

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This commit is contained in:
Stephen Halter 2025-06-19 08:40:11 -07:00 • committed by GitHub
commit a4b4edaa2a
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4 changed files with 93 additions and 11 deletions
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4
src/ModelContextProtocol.Core/Client/SseClientSessionTransport.cs
View file

@ -91,7 +91,7 @@ internal sealed partial class SseClientSessionTransport : TransportBase
{
Content = content,
};
StreamableHttpClientSessionTransport.CopyAdditionalHeaders(httpRequestMessage.Headers, _options.AdditionalHeaders);
StreamableHttpClientSessionTransport.CopyAdditionalHeaders(httpRequestMessage.Headers, _options.AdditionalHeaders, sessionId: null, protocolVersion: null);
var response = await _httpClient.SendAsync(httpRequestMessage, cancellationToken).ConfigureAwait(false);
if (!response.IsSuccessStatusCode)
@ -152,7 +152,7 @@ internal sealed partial class SseClientSessionTransport : TransportBase
{
using var request = new HttpRequestMessage(HttpMethod.Get, _sseEndpoint);
request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("text/event-stream"));
StreamableHttpClientSessionTransport.CopyAdditionalHeaders(request.Headers, _options.AdditionalHeaders);
StreamableHttpClientSessionTransport.CopyAdditionalHeaders(request.Headers, _options.AdditionalHeaders, sessionId: null, protocolVersion: null);
using var response = await _httpClient.SendAsync(
request,

37
src/ModelContextProtocol.Core/Client/StreamableHttpClientSessionTransport.cs
View file

@ -30,6 +30,9 @@ internal sealed partial class StreamableHttpClientSessionTransport : TransportBa
private string? _negotiatedProtocolVersion;
private Task? _getReceiveTask;
private readonly SemaphoreSlim _disposeLock = new(1, 1);
private bool _disposed;
public StreamableHttpClientSessionTransport(
string endpointName,
SseClientTransportOptions transportOptions,
@ -138,12 +141,26 @@ internal sealed partial class StreamableHttpClientSessionTransport : TransportBa
public override async ValueTask DisposeAsync()
{
using var _ = await _disposeLock.LockAsync().ConfigureAwait(false);
if (_disposed)
{
return;
}
_disposed = true;
try
{
await _connectionCts.CancelAsync().ConfigureAwait(false);
try
{
// Send DELETE request to terminate the session. Only send if we have a session ID, per MCP spec.
if (!string.IsNullOrEmpty(SessionId))
{
await SendDeleteRequest();
}
if (_getReceiveTask != null)
{
await _getReceiveTask.ConfigureAwait(false);
@ -236,6 +253,22 @@ internal sealed partial class StreamableHttpClientSessionTransport : TransportBa
return null;
}
private async Task SendDeleteRequest()
{
using var deleteRequest = new HttpRequestMessage(HttpMethod.Delete, _options.Endpoint);
CopyAdditionalHeaders(deleteRequest.Headers, _options.AdditionalHeaders, SessionId, _negotiatedProtocolVersion);
try
{
// Do not validate we get a successful status code, because server support for the DELETE request is optional
(await _httpClient.SendAsync(deleteRequest, CancellationToken.None).ConfigureAwait(false)).Dispose();
}
catch (Exception ex)
{
LogTransportShutdownFailed(Name, ex);
}
}
private void LogJsonException(JsonException ex, string data)
{
if (_logger.IsEnabled(LogLevel.Trace))
@ -251,8 +284,8 @@ internal sealed partial class StreamableHttpClientSessionTransport : TransportBa
internal static void CopyAdditionalHeaders(
HttpRequestHeaders headers,
IDictionary<string, string>? additionalHeaders,
string? sessionId = null,
string? protocolVersion = null)
string? sessionId,
string? protocolVersion)
{
if (sessionId is not null)
{

42
tests/ModelContextProtocol.AspNetCore.Tests/StreamableHttpClientConformanceTests.cs
View file

@ -14,8 +14,10 @@ namespace ModelContextProtocol.AspNetCore.Tests;
public class StreamableHttpClientConformanceTests(ITestOutputHelper outputHelper) : KestrelInMemoryTest(outputHelper), IAsyncDisposable
{
private WebApplication? _app;
private readonly List<string> _deleteRequestSessionIds = [];
private async Task StartAsync()
// Don't add the delete endpoint by default to ensure the client still works with basic sessionless servers.
private async Task StartAsync(bool enableDelete = false)
{
Builder.Services.Configure<JsonOptions>(options =>
{
@ -28,7 +30,7 @@ public class StreamableHttpClientConformanceTests(ITestOutputHelper outputHelper
Services = _app.Services,
});
_app.MapPost("/mcp", (JsonRpcMessage message) =>
_app.MapPost("/mcp", (JsonRpcMessage message, HttpContext context) =>
{
if (message is not JsonRpcRequest request)
{
@ -36,6 +38,12 @@ public class StreamableHttpClientConformanceTests(ITestOutputHelper outputHelper
return Results.Accepted();
}
if (enableDelete)
{
// Add a session ID to the response to enable session tracking
context.Response.Headers.Append("mcp-session-id", "test-session-123");
}
if (request.Method == "initialize")
{
return Results.Json(new JsonRpcResponse
@ -87,6 +95,15 @@ public class StreamableHttpClientConformanceTests(ITestOutputHelper outputHelper
throw new Exception("Unexpected message!");
});
if (enableDelete)
{
_app.MapDelete("/mcp", context =>
{
_deleteRequestSessionIds.Add(context.Request.Headers["mcp-session-id"].ToString());
return Task.CompletedTask;
});
}
await _app.StartAsync(TestContext.Current.CancellationToken);
}
@ -136,6 +153,27 @@ public class StreamableHttpClientConformanceTests(ITestOutputHelper outputHelper
await Task.WhenAll(echoTasks);
}
[Fact]
public async Task SendsDeleteRequestOnDispose()
{
await StartAsync(enableDelete: true);
await using var transport = new SseClientTransport(new()
{
Endpoint = new("http://localhost/mcp"),
TransportMode = HttpTransportMode.StreamableHttp,
}, HttpClient, LoggerFactory);
await using var client = await McpClientFactory.CreateAsync(transport, loggerFactory: LoggerFactory, cancellationToken: TestContext.Current.CancellationToken);
// Dispose should trigger DELETE request
await client.DisposeAsync();
// Verify DELETE request was sent with correct session ID
var sessionId = Assert.Single(_deleteRequestSessionIds);
Assert.Equal("test-session-123", sessionId);
}
private static async Task CallEchoAndValidateAsync(McpClientTool echoTool)
{
var response = await echoTool.CallAsync(new Dictionary<string, object?>() { ["message"] = "Hello world!" }, cancellationToken: TestContext.Current.CancellationToken);

21
tests/ModelContextProtocol.AspNetCore.Tests/Utils/KestrelInMemoryConnection.cs
View file

@ -65,10 +65,21 @@ public sealed class KestrelInMemoryConnection : ConnectionContext
public override bool CanWrite => true;
public override bool CanSeek => false;
public override Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
=> _readStream.ReadAsync(buffer, offset, count, cancellationToken);
public override ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken = default)
=> _readStream.ReadAsync(buffer, cancellationToken);
public override async Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
{
// Normally, Kestrel will trigger RequestAborted when the connectionClosedCts fires causing it to gracefully close
// the connection. However, there's currently a race condition that can cause this to get missed. This at least
// unblocks HttpConnection.SendAsync when it disposes the underlying connection stream while awaiting the _readAheadTask
// as would happen with a real socket. https://github.com/dotnet/aspnetcore/pull/62385
using var linkedTokenSource = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken, connectionClosedCts.Token);
return await _readStream.ReadAsync(buffer, offset, count, linkedTokenSource.Token);
}
public override async ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken = default)
{
using var linkedTokenSource = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken, connectionClosedCts.Token);
return await _readStream.ReadAsync(buffer, linkedTokenSource.Token);
}
public override Task WriteAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
=> _writeStream.WriteAsync(buffer, offset, count, cancellationToken);
@ -81,7 +92,7 @@ public sealed class KestrelInMemoryConnection : ConnectionContext
protected override void Dispose(bool disposing)
{
// Signal to the server the the client has closed the connection, and dispose the client-half of the Pipes.
connectionClosedCts.Cancel();
ThreadPool.UnsafeQueueUserWorkItem(static cts => ((CancellationTokenSource)cts!).Cancel(), connectionClosedCts);
duplexPipe.Input.Complete();
duplexPipe.Output.Complete();
}