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Sampling capability (#7)

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Peder Holdgaard Pedersen 2025-01-05 20:05:32 +01:00 • committed by GitHub
commit 8c6dfd53c8
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2 changed files with 370 additions and 9 deletions
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5
src/mcpdotnet/Client/IMcpClient.cs
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@ -25,6 +25,11 @@ public interface IMcpClient : IAsyncDisposable
/// </summary>
Implementation? ServerInfo { get; }
/// <summary>
/// Gets or sets the handler for the server's sampling requests.
/// </summary>
Func<CreateMessageRequestParams, Task<CreateMessageResult>>? SamplingHandler { get; set; }
/// <summary>
/// Establishes a connection to the server.
/// </summary>

64
src/mcpdotnet/Client/McpClient.cs
View file

@ -7,6 +7,8 @@ using McpDotNet.Protocol.Messages;
using System.Diagnostics;
using System.Text.Json;
using McpDotNet.Utils.Json;
using System.Text;
using System.Threading;
/// <inheritdoc/>
internal class McpClient : IMcpClient
@ -15,6 +17,7 @@ internal class McpClient : IMcpClient
private readonly McpClientOptions _options;
private readonly ConcurrentDictionary<RequestId, TaskCompletionSource<IJsonRpcMessage>> _pendingRequests;
private readonly ConcurrentDictionary<string, List<Func<JsonRpcNotification,Task>>> _notificationHandlers;
private readonly Dictionary<string, Func<JsonRpcRequest, Task<object>>> _requestHandlers = new();
private int _nextRequestId;
private bool _isInitialized;
private Task? _messageProcessingTask;
@ -42,6 +45,17 @@ internal class McpClient : IMcpClient
_pendingRequests = new();
_notificationHandlers = new();
_nextRequestId = 1;
if (options.Capabilities?.Sampling != null)
{
SetRequestHandler<CreateMessageRequestParams, CreateMessageResult>("sampling/createMessage",
async (request) => {
if (SamplingHandler == null)
throw new McpClientException("Sampling handler not configured");
return await SamplingHandler(request);
});
}
}
/// <inheritdoc/>
@ -271,7 +285,7 @@ internal class McpClient : IMcpClient
{
await foreach (var message in _transport.MessageReader.ReadAllAsync(cancellationToken).ConfigureAwait(false))
{
await HandleMessageAsync(message).ConfigureAwait(false);
await HandleMessageAsync(message, cancellationToken).ConfigureAwait(false);
}
}
catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
@ -284,10 +298,39 @@ internal class McpClient : IMcpClient
}
}
private async Task HandleMessageAsync(IJsonRpcMessage message)
private async Task HandleMessageAsync(IJsonRpcMessage message, CancellationToken cancellationToken)
{
switch (message)
{
case JsonRpcRequest request:
if (_requestHandlers.TryGetValue(request.Method, out var handler))
{
try
{
var result = await handler(request);
await _transport.SendMessageAsync(new JsonRpcResponse
{
Id = request.Id,
JsonRpc = "2.0",
Result = result
}, cancellationToken);
}
catch (Exception ex)
{
// Send error response
await _transport.SendMessageAsync(new JsonRpcError
{
Id = request.Id,
JsonRpc = "2.0",
Error = new JsonRpcErrorDetail
{
Code = -32000, // Implementation defined error
Message = ex.Message
}
}, cancellationToken);
}
}
break;
case IJsonRpcMessageWithId messageWithId:
if (_pendingRequests.TryRemove(messageWithId.Id, out var tcs))
{
@ -298,11 +341,11 @@ internal class McpClient : IMcpClient
case JsonRpcNotification notification:
if (_notificationHandlers.TryGetValue(notification.Method, out var handlers))
{
foreach (var handler in handlers)
foreach (var notificationHandler in handlers)
{
try
{
await handler(notification).ConfigureAwait(false);
await notificationHandler(notification).ConfigureAwait(false);
}
catch (Exception ex)
{
@ -383,6 +426,18 @@ internal class McpClient : IMcpClient
}
}
public Func<CreateMessageRequestParams, Task<CreateMessageResult>>? SamplingHandler { get; set; }
private void SetRequestHandler<TRequest, TResponse>(string method, Func<TRequest, Task<TResponse>> handler)
{
_requestHandlers[method] = async (request) => {
// Convert the params JsonElement to our type using the same options
var jsonString = JsonSerializer.Serialize(request.Params);
var typedRequest = JsonSerializer.Deserialize<TRequest>(jsonString, _jsonOptions);
return await handler(typedRequest);
};
}
private async Task CleanupAsync()
{
_cts?.Cancel();
@ -419,3 +474,4 @@ internal class McpClient : IMcpClient
GC.SuppressFinalize(this);
}
}