Class McpOperationHandler

java.lang.Object

dev.langchain4j.mcp.client.transport.McpOperationHandler

public class McpOperationHandler
extends Object

Handles incoming messages from the MCP server.

A transport calls onMessage(String) for every message it receives, and expectResponse(Long, java.util.concurrent.CompletableFuture) before sending a request, to register the id whose response it is waiting for.

Constructor Summary

Constructors

Constructor	Description
McpOperationHandler(Map<Long, CompletableFuture<String>> pendingOperations, Supplier<List<McpRoot>> roots, McpTransport transport, Consumer<McpLogMessage> logMessageConsumer, Runnable onToolListUpdate, Runnable onResourceListUpdate, Runnable onPromptListUpdate, Consumer<String> onResourceUpdate, McpProgressHandler progressHandler, Runnable onServerPing, Runnable onServerRootsList, BiConsumer<Long,String> onServerCancelled, BiConsumer<Long, Map<String,Object>> onSubscriptionAcknowledged)
McpOperationHandler(Map<Long, CompletableFuture<String>> pendingOperations, Supplier<List<McpRoot>> roots, McpTransport transport, Consumer<McpLogMessage> logMessageConsumer, Runnable onToolListUpdate, Runnable onResourceListUpdate, Runnable onPromptListUpdate, Consumer<String> onResourceUpdate, McpProgressHandler progressHandler, Runnable onServerPing, Runnable onServerRootsList, BiConsumer<Long,String> onServerCancelled, BiConsumer<Long, Map<String,Object>> onSubscriptionAcknowledged, @Nullable Consumer<McpServerMessageContext> onServerMessage)

Method Summary

Modifier and Type	Method	Description
void	cancelAllPendingOperations(String reason)
void	expectResponse(Long id, CompletableFuture<String> future)	Registers a client-initiated request whose response is awaited; the future is completed with the response as unparsed JSON text.
void	onMessage(String json)	Handles an inbound message from the server, taken exactly as it arrived on the wire, so that a transport does not have to parse it first.

Methods inherited from class Object

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

Constructor Details

McpOperationHandler

public McpOperationHandler(Map<Long, CompletableFuture<String>> pendingOperations,
 Supplier<List<McpRoot>> roots,
 McpTransport transport,
 Consumer<McpLogMessage> logMessageConsumer,
 Runnable onToolListUpdate,
 Runnable onResourceListUpdate,
 Runnable onPromptListUpdate,
 Consumer<String> onResourceUpdate,
 McpProgressHandler progressHandler,
 Runnable onServerPing,
 Runnable onServerRootsList,
 BiConsumer<Long,String> onServerCancelled,
 BiConsumer<Long, Map<String,Object>> onSubscriptionAcknowledged)

McpOperationHandler

public McpOperationHandler(Map<Long, CompletableFuture<String>> pendingOperations,
 Supplier<List<McpRoot>> roots,
 McpTransport transport,
 Consumer<McpLogMessage> logMessageConsumer,
 Runnable onToolListUpdate,
 Runnable onResourceListUpdate,
 Runnable onPromptListUpdate,
 Consumer<String> onResourceUpdate,
 McpProgressHandler progressHandler,
 Runnable onServerPing,
 Runnable onServerRootsList,
 BiConsumer<Long,String> onServerCancelled,
 BiConsumer<Long, Map<String,Object>> onSubscriptionAcknowledged,
 @Nullable Consumer<McpServerMessageContext> onServerMessage)

Parameters:

onServerMessage - called with every request and notification from the server, before it's handled

Method Details

onMessage

public void onMessage(String json)

Handles an inbound message from the server, taken exactly as it arrived on the wire, so that a transport does not have to parse it first.

Valid JSON that is not a JSON-RPC object - a batch array, a scalar, a bare null - is ignored. Text that is not valid JSON at all throws, so that the transport can decide: fail the pending operation, or log and keep reading.

Throws:

IllegalArgumentException - if the message is not valid JSON, or JsonException from a codec that reports the typed exceptions.

expectResponse

public void expectResponse(Long id,
 CompletableFuture<String> future)

Registers a client-initiated request whose response is awaited; the future is completed with the response as unparsed JSON text. Cancelling the future removes its registration.

cancelAllPendingOperations

public void cancelAllPendingOperations(String reason)