Module io.modelcontextprotocol.sdk.mcp

Package io.modelcontextprotocol.spec

Class McpClientSession

java.lang.Object

io.modelcontextprotocol.spec.McpClientSession

All Implemented Interfaces:

McpSession

public class McpClientSession
extends Object
implements McpSession

Default implementation of the MCP (Model Context Protocol) session that manages bidirectional JSON-RPC communication between clients and servers. This implementation follows the MCP specification for message exchange and transport handling.

The session manages:

• Request/response handling with unique message IDs
• Notification processing
• Message timeout management
• Transport layer abstraction

Author:

Christian Tzolov, Dariusz Jędrzejczyk, Yanming Zhou

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	McpClientSession.NotificationHandler	Functional interface for handling incoming JSON-RPC notifications.
static interface	McpClientSession.RequestHandler<T>	Functional interface for handling incoming JSON-RPC requests.

Constructor Summary

Constructors

Constructor	Description
McpClientSession(Duration requestTimeout, McpClientTransport transport, Map<String,McpClientSession.RequestHandler<?>> requestHandlers, Map<String,McpClientSession.NotificationHandler> notificationHandlers)	Deprecated. Use McpClientSession(Duration, McpClientTransport, Map, Map, Function)
McpClientSession(Duration requestTimeout, McpClientTransport transport, Map<String,McpClientSession.RequestHandler<?>> requestHandlers, Map<String,McpClientSession.NotificationHandler> notificationHandlers, Function<? super reactor.core.publisher.Mono<Void>,? extends org.reactivestreams.Publisher<Void>> connectHook)	Creates a new McpClientSession with the specified configuration and handlers.

Method Summary

Modifier and Type	Method	Description
void	close()	Closes the session immediately, potentially interrupting pending operations.
reactor.core.publisher.Mono<Void>	closeGracefully()	Closes the session gracefully, allowing pending operations to complete.
reactor.core.publisher.Mono<Void>	sendNotification(String method, Object params)	Sends a JSON-RPC notification.
<T> reactor.core.publisher.Mono<T>	sendRequest(String method, Object requestParams, com.fasterxml.jackson.core.type.TypeReference<T> typeRef)	Sends a JSON-RPC request and returns the response.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface io.modelcontextprotocol.spec.McpSession

sendNotification

Constructor Details

McpClientSession

@Deprecated
public McpClientSession(Duration requestTimeout,
 McpClientTransport transport,
 Map<String,McpClientSession.RequestHandler<?>> requestHandlers,
 Map<String,McpClientSession.NotificationHandler> notificationHandlers)

Deprecated.

Use McpClientSession(Duration, McpClientTransport, Map, Map, Function)

Creates a new McpClientSession with the specified configuration and handlers.

Parameters:

requestTimeout - Duration to wait for responses

transport - Transport implementation for message exchange

requestHandlers - Map of method names to request handlers

notificationHandlers - Map of method names to notification handlers

McpClientSession

public McpClientSession(Duration requestTimeout,
 McpClientTransport transport,
 Map<String,McpClientSession.RequestHandler<?>> requestHandlers,
 Map<String,McpClientSession.NotificationHandler> notificationHandlers,
 Function<? super reactor.core.publisher.Mono<Void>,? extends org.reactivestreams.Publisher<Void>> connectHook)

Creates a new McpClientSession with the specified configuration and handlers.

Parameters:

requestTimeout - Duration to wait for responses

transport - Transport implementation for message exchange

requestHandlers - Map of method names to request handlers

notificationHandlers - Map of method names to notification handlers

connectHook - Hook that allows transforming the connection Publisher prior to subscribing

Method Details

sendRequest

public <T> reactor.core.publisher.Mono<T> sendRequest(String method,
 Object requestParams,
 com.fasterxml.jackson.core.type.TypeReference<T> typeRef)

Sends a JSON-RPC request and returns the response.

Specified by:

sendRequest in interface McpSession

Type Parameters:

T - The expected response type

Parameters:

method - The method name to call

requestParams - The request parameters

typeRef - Type reference for response deserialization

Returns:

A Mono containing the response

sendNotification

public reactor.core.publisher.Mono<Void> sendNotification(String method,
 Object params)

Sends a JSON-RPC notification.

Specified by:

sendNotification in interface McpSession

Parameters:

method - The method name for the notification

params - The notification parameters

Returns:

A Mono that completes when the notification is sent

closeGracefully

public reactor.core.publisher.Mono<Void> closeGracefully()

Closes the session gracefully, allowing pending operations to complete.

Specified by:

closeGracefully in interface McpSession

Returns:

A Mono that completes when the session is closed

close

public void close()

Closes the session immediately, potentially interrupting pending operations.

Specified by:

close in interface McpSession