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Improve testing for StreamableHttpHandler and IdleTrackingBackgroundService (#345)

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* Add idle session pruning tests
* Remove redundant CTS from StreamableHttpHandler
  * StreamableHttpServerTransport.HandlePostRequest already creates the equivelant CTS
    which DeleteRequest_CompletesSession_WhichCancelsLongRunningToolCalls verifies
* Fix accept header validation for GET
* Use InvalidOperationException for transport-not-connected errors in doc comments
* Fix flaky Cancellation_ThrowsCancellationException test
This commit is contained in:
Stephen Halter 2025-04-24 10:49:02 -07:00 • committed by GitHub
commit e3ff552824
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1 changed files with 315 additions and 291 deletions
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40
src/ModelContextProtocol.AspNetCore/StreamableHttpHandler.cs
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@ -3,6 +3,7 @@ using Microsoft.AspNetCore.Http.Features;
using Microsoft.AspNetCore.WebUtilities;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using Microsoft.Net.Http.Headers;
using ModelContextProtocol.Protocol.Messages;
using ModelContextProtocol.Protocol.Transport;
using ModelContextProtocol.Server;
@ -23,18 +24,19 @@ internal sealed class StreamableHttpHandler(
IServiceProvider applicationServices)
{
private static JsonTypeInfo<JsonRpcError> s_errorTypeInfo = GetRequiredJsonTypeInfo<JsonRpcError>();
private static MediaTypeHeaderValue ApplicationJsonMediaType = new("application/json");
private static MediaTypeHeaderValue TextEventStreamMediaType = new("text/event-stream");
public ConcurrentDictionary<string, HttpMcpSession<StreamableHttpServerTransport>> Sessions { get; } = new(StringComparer.Ordinal);
public async Task HandlePostRequestAsync(HttpContext context)
{
// The Streamable HTTP spec mandates the client MUST accept both application/json and text/event-stream.
// ASP.NET Core Minimal APIs mostly ry to stay out of the business of response content negotiation, so
// we have to do this manually. The spec doesn't mandate that servers MUST reject these requests, but it's
// probably good to at least start out trying to be strict.
var acceptHeader = context.Request.Headers.Accept.ToString();
if (!acceptHeader.Contains("application/json", StringComparison.Ordinal) ||
!acceptHeader.Contains("text/event-stream", StringComparison.Ordinal))
// ASP.NET Core Minimal APIs mostly try to stay out of the business of response content negotiation,
// so we have to do this manually. The spec doesn't mandate that servers MUST reject these requests,
// but it's probably good to at least start out trying to be strict.
var acceptHeaders = context.Request.GetTypedHeaders().Accept;
if (!acceptHeaders.Contains(ApplicationJsonMediaType) || !acceptHeaders.Contains(TextEventStreamMediaType))
{
await WriteJsonRpcErrorAsync(context,
"Not Acceptable: Client must accept both application/json and text/event-stream",
@ -49,9 +51,8 @@ internal sealed class StreamableHttpHandler(
}
using var _ = session.AcquireReference();
using var cts = CancellationTokenSource.CreateLinkedTokenSource(context.RequestAborted, session.SessionClosed);
InitializeSseResponse(context);
var wroteResponse = await session.Transport.HandlePostRequest(new HttpDuplexPipe(context), cts.Token);
var wroteResponse = await session.Transport.HandlePostRequest(new HttpDuplexPipe(context), context.RequestAborted);
if (!wroteResponse)
{
// We wound up writing nothing, so there should be no Content-Type response header.
@ -62,8 +63,8 @@ internal sealed class StreamableHttpHandler(
public async Task HandleGetRequestAsync(HttpContext context)
{
var acceptHeader = context.Request.Headers.Accept.ToString();
if (!acceptHeader.Contains("application/json", StringComparison.Ordinal))
var acceptHeaders = context.Request.GetTypedHeaders().Accept;
if (!acceptHeaders.Contains(TextEventStreamMediaType))
{
await WriteJsonRpcErrorAsync(context,
"Not Acceptable: Client must accept text/event-stream",
@ -105,12 +106,6 @@ internal sealed class StreamableHttpHandler(
}
}
private void InitializeSessionResponse(HttpContext context, HttpMcpSession<StreamableHttpServerTransport> session)
{
context.Response.Headers["mcp-session-id"] = session.Id;
context.Features.Set(session.Server);
}
private async ValueTask<HttpMcpSession<StreamableHttpServerTransport>?> GetSessionAsync(HttpContext context, string sessionId)
{
if (Sessions.TryGetValue(sessionId, out var existingSession))
@ -123,7 +118,8 @@ internal sealed class StreamableHttpHandler(
return null;
}
InitializeSessionResponse(context, existingSession);
context.Response.Headers["mcp-session-id"] = existingSession.Id;
context.Features.Set(existingSession.Server);
return existingSession;
}
@ -138,11 +134,10 @@ internal sealed class StreamableHttpHandler(
private async ValueTask<HttpMcpSession<StreamableHttpServerTransport>?> GetOrCreateSessionAsync(HttpContext context)
{
var sessionId = context.Request.Headers["mcp-session-id"].ToString();
HttpMcpSession<StreamableHttpServerTransport>? session;
if (string.IsNullOrEmpty(sessionId))
{
session = await CreateSessionAsync(context);
var session = await CreateSessionAsync(context);
if (!Sessions.TryAdd(session.Id, session))
{
@ -159,6 +154,9 @@ internal sealed class StreamableHttpHandler(
private async ValueTask<HttpMcpSession<StreamableHttpServerTransport>> CreateSessionAsync(HttpContext context)
{
var sessionId = MakeNewSessionId();
context.Response.Headers["mcp-session-id"] = sessionId;
var mcpServerOptions = mcpServerOptionsSnapshot.Value;
if (httpMcpServerOptions.Value.ConfigureSessionOptions is { } configureSessionOptions)
{
@ -169,8 +167,9 @@ internal sealed class StreamableHttpHandler(
var transport = new StreamableHttpServerTransport();
// Use application instead of request services, because the session will likely outlive the first initialization request.
var server = McpServerFactory.Create(transport, mcpServerOptions, loggerFactory, applicationServices);
context.Features.Set(server);
var session = new HttpMcpSession<StreamableHttpServerTransport>(MakeNewSessionId(), transport, context.User, httpMcpServerOptions.Value.TimeProvider)
var session = new HttpMcpSession<StreamableHttpServerTransport>(sessionId, transport, context.User, httpMcpServerOptions.Value.TimeProvider)
{
Server = server,
};
@ -178,7 +177,6 @@ internal sealed class StreamableHttpHandler(
var runSessionAsync = httpMcpServerOptions.Value.RunSessionHandler ?? RunSessionAsync;
session.ServerRunTask = runSessionAsync(context, server, session.SessionClosed);
InitializeSessionResponse(context, session);
return session;
}