Restructure IMcpEndpoint, IMcpClient, and IMcpServer (#723)

* Remove `McpEndpoint` & `IMcpClient`

* Revise naming, add abstract classes

* Fix missing renames

* Move extension methods to instance methods

* Add back old API, but obsoleted

* Add back obsoleted factory classes

* Move deprecation attributes

* `SseClientTransport` -> `HttpClientTransport`

* Update src/ModelContextProtocol.Core/Server/AugmentedServiceProvider.cs

Co-authored-by: Stephen Halter <halter73@gmail.com>

* PR feedback

* PR feedback

* Add back dispose lock

* Fix docs projects

* PR feedback

* Undo `docs/*.md` changes

---------

Co-authored-by: Stephen Halter <halter73@gmail.com>
This commit is contained in:
Mackinnon Buck 2025-09-16 13:22:10 -04:00 • committed by GitHub
commit 38b4a26998
No known key found for this signature in database
GPG key ID: B5690EEEBB952194

View file

@ -1,236 +1,49 @@
using Microsoft.Extensions.Logging;
using ModelContextProtocol.Protocol;
using System.Text.Json;
using ModelContextProtocol.Protocol;
namespace ModelContextProtocol.Client;
/// <inheritdoc/>
internal sealed partial class McpClient : McpEndpoint, IMcpClient
/// <summary>
/// Represents an instance of a Model Context Protocol (MCP) client session that connects to and communicates with an MCP server.
/// </summary>
#pragma warning disable CS0618 // Type or member is obsolete
public abstract partial class McpClient : McpSession, IMcpClient
#pragma warning restore CS0618 // Type or member is obsolete
{
private static Implementation DefaultImplementation { get; } = new()
{
Name = DefaultAssemblyName.Name ?? nameof(McpClient),
Version = DefaultAssemblyName.Version?.ToString() ?? "1.0.0",
};
private readonly IClientTransport _clientTransport;
private readonly McpClientOptions _options;
private ITransport? _sessionTransport;
private CancellationTokenSource? _connectCts;
private ServerCapabilities? _serverCapabilities;
private Implementation? _serverInfo;
private string? _serverInstructions;
/// <summary>
/// Gets the capabilities supported by the connected server.
/// </summary>
/// <exception cref="InvalidOperationException">The client is not connected.</exception>
public abstract ServerCapabilities ServerCapabilities { get; }
/// <summary>
/// Initializes a new instance of the <see cref="McpClient"/> class.
/// Gets the implementation information of the connected server.
/// </summary>
/// <param name="clientTransport">The transport to use for communication with the server.</param>
/// <param name="options">Options for the client, defining protocol version and capabilities.</param>
/// <param name="loggerFactory">The logger factory.</param>
public McpClient(IClientTransport clientTransport, McpClientOptions? options, ILoggerFactory? loggerFactory)
: base(loggerFactory)
{
options ??= new();
_clientTransport = clientTransport;
_options = options;
EndpointName = clientTransport.Name;
if (options.Capabilities is { } capabilities)
{
if (capabilities.NotificationHandlers is { } notificationHandlers)
{
NotificationHandlers.RegisterRange(notificationHandlers);
}
if (capabilities.Sampling is { } samplingCapability)
{
if (samplingCapability.SamplingHandler is not { } samplingHandler)
{
throw new InvalidOperationException("Sampling capability was set but it did not provide a handler.");
}
RequestHandlers.Set(
RequestMethods.SamplingCreateMessage,
(request, _, cancellationToken) => samplingHandler(
request,
request?.ProgressToken is { } token ? new TokenProgress(this, token) : NullProgress.Instance,
cancellationToken),
McpJsonUtilities.JsonContext.Default.CreateMessageRequestParams,
McpJsonUtilities.JsonContext.Default.CreateMessageResult);
}
if (capabilities.Roots is { } rootsCapability)
{
if (rootsCapability.RootsHandler is not { } rootsHandler)
{
throw new InvalidOperationException("Roots capability was set but it did not provide a handler.");
}
RequestHandlers.Set(
RequestMethods.RootsList,
(request, _, cancellationToken) => rootsHandler(request, cancellationToken),
McpJsonUtilities.JsonContext.Default.ListRootsRequestParams,
McpJsonUtilities.JsonContext.Default.ListRootsResult);
}
if (capabilities.Elicitation is { } elicitationCapability)
{
if (elicitationCapability.ElicitationHandler is not { } elicitationHandler)
{
throw new InvalidOperationException("Elicitation capability was set but it did not provide a handler.");
}
RequestHandlers.Set(
RequestMethods.ElicitationCreate,
(request, _, cancellationToken) => elicitationHandler(request, cancellationToken),
McpJsonUtilities.JsonContext.Default.ElicitRequestParams,
McpJsonUtilities.JsonContext.Default.ElicitResult);
}
}
}
/// <inheritdoc/>
public string? SessionId
{
get
{
if (_sessionTransport is null)
{
throw new InvalidOperationException("Must have already initialized a session when invoking this property.");
}
return _sessionTransport.SessionId;
}
}
/// <inheritdoc/>
public ServerCapabilities ServerCapabilities => _serverCapabilities ?? throw new InvalidOperationException("The client is not connected.");
/// <inheritdoc/>
public Implementation ServerInfo => _serverInfo ?? throw new InvalidOperationException("The client is not connected.");
/// <inheritdoc/>
public string? ServerInstructions => _serverInstructions;
/// <inheritdoc/>
public override string EndpointName { get; }
/// <remarks>
/// <para>
/// This property provides identification details about the connected server, including its name and version.
/// It is populated during the initialization handshake and is available after a successful connection.
/// </para>
/// <para>
/// This information can be useful for logging, debugging, compatibility checks, and displaying server
/// information to users.
/// </para>
/// </remarks>
/// <exception cref="InvalidOperationException">The client is not connected.</exception>
public abstract Implementation ServerInfo { get; }
/// <summary>
/// Asynchronously connects to an MCP server, establishes the transport connection, and completes the initialization handshake.
/// Gets any instructions describing how to use the connected server and its features.
/// </summary>
public async Task ConnectAsync(CancellationToken cancellationToken = default)
{
_connectCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
cancellationToken = _connectCts.Token;
try
{
// Connect transport
_sessionTransport = await _clientTransport.ConnectAsync(cancellationToken).ConfigureAwait(false);
InitializeSession(_sessionTransport);
// We don't want the ConnectAsync token to cancel the session after we've successfully connected.
// The base class handles cleaning up the session in DisposeAsync without our help.
StartSession(_sessionTransport, fullSessionCancellationToken: CancellationToken.None);
// Perform initialization sequence
using var initializationCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
initializationCts.CancelAfter(_options.InitializationTimeout);
try
{
// Send initialize request
string requestProtocol = _options.ProtocolVersion ?? McpSession.LatestProtocolVersion;
var initializeResponse = await this.SendRequestAsync(
RequestMethods.Initialize,
new InitializeRequestParams
{
ProtocolVersion = requestProtocol,
Capabilities = _options.Capabilities ?? new ClientCapabilities(),
ClientInfo = _options.ClientInfo ?? DefaultImplementation,
},
McpJsonUtilities.JsonContext.Default.InitializeRequestParams,
McpJsonUtilities.JsonContext.Default.InitializeResult,
cancellationToken: initializationCts.Token).ConfigureAwait(false);
// Store server information
if (_logger.IsEnabled(LogLevel.Information))
{
LogServerCapabilitiesReceived(EndpointName,
capabilities: JsonSerializer.Serialize(initializeResponse.Capabilities, McpJsonUtilities.JsonContext.Default.ServerCapabilities),
serverInfo: JsonSerializer.Serialize(initializeResponse.ServerInfo, McpJsonUtilities.JsonContext.Default.Implementation));
}
_serverCapabilities = initializeResponse.Capabilities;
_serverInfo = initializeResponse.ServerInfo;
_serverInstructions = initializeResponse.Instructions;
// Validate protocol version
bool isResponseProtocolValid =
_options.ProtocolVersion is { } optionsProtocol ? optionsProtocol == initializeResponse.ProtocolVersion :
McpSession.SupportedProtocolVersions.Contains(initializeResponse.ProtocolVersion);
if (!isResponseProtocolValid)
{
LogServerProtocolVersionMismatch(EndpointName, requestProtocol, initializeResponse.ProtocolVersion);
throw new McpException($"Server protocol version mismatch. Expected {requestProtocol}, got {initializeResponse.ProtocolVersion}");
}
// Send initialized notification
await this.SendNotificationAsync(
NotificationMethods.InitializedNotification,
new InitializedNotificationParams(),
McpJsonUtilities.JsonContext.Default.InitializedNotificationParams,
cancellationToken: initializationCts.Token).ConfigureAwait(false);
}
catch (OperationCanceledException oce) when (initializationCts.IsCancellationRequested && !cancellationToken.IsCancellationRequested)
{
LogClientInitializationTimeout(EndpointName);
throw new TimeoutException("Initialization timed out", oce);
}
}
catch (Exception e)
{
LogClientInitializationError(EndpointName, e);
await DisposeAsync().ConfigureAwait(false);
throw;
}
}
/// <inheritdoc/>
public override async ValueTask DisposeUnsynchronizedAsync()
{
try
{
if (_connectCts is not null)
{
await _connectCts.CancelAsync().ConfigureAwait(false);
_connectCts.Dispose();
}
await base.DisposeUnsynchronizedAsync().ConfigureAwait(false);
}
finally
{
if (_sessionTransport is not null)
{
await _sessionTransport.DisposeAsync().ConfigureAwait(false);
}
}
}
[LoggerMessage(Level = LogLevel.Information, Message = "{EndpointName} client received server '{ServerInfo}' capabilities: '{Capabilities}'.")]
private partial void LogServerCapabilitiesReceived(string endpointName, string capabilities, string serverInfo);
[LoggerMessage(Level = LogLevel.Error, Message = "{EndpointName} client initialization error.")]
private partial void LogClientInitializationError(string endpointName, Exception exception);
[LoggerMessage(Level = LogLevel.Error, Message = "{EndpointName} client initialization timed out.")]
private partial void LogClientInitializationTimeout(string endpointName);
[LoggerMessage(Level = LogLevel.Error, Message = "{EndpointName} client protocol version mismatch with server. Expected '{Expected}', received '{Received}'.")]
private partial void LogServerProtocolVersionMismatch(string endpointName, string expected, string received);
}
/// <remarks>
/// <para>
/// This property contains instructions provided by the server during initialization that explain
/// how to effectively use its capabilities. These instructions can include details about available
/// tools, expected input formats, limitations, or any other helpful information.
/// </para>
/// <para>
/// This can be used by clients to improve an LLM's understanding of available tools, prompts, and resources.
/// It can be thought of like a "hint" to the model and may be added to a system prompt.
/// </para>
/// </remarks>
public abstract string? ServerInstructions { get; }
}