Attempting to structure the client API with sync and async abstractions

src/main/java/spring/ai/mcp/McpApplication.java

@@ -5,6 +5,7 @@ import java.util.List;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 import spring.ai.mcp.client.McpClient;
+import spring.ai.mcp.client.McpSyncClient;
 import spring.ai.mcp.client.stdio.StdioServerParameters;
 import spring.ai.mcp.client.stdio.StdioServerTransport;
 
@@ -41,7 +42,7 @@ public class McpApplication {
 	}
 
 	@Bean
-	public List<McpFunctionCallback> functionCallbacks(McpClient mcpClient) {
+	public List<McpFunctionCallback> functionCallbacks(McpSyncClient mcpClient) {
 
 		return mcpClient.listTools(null)
 			.tools()
@@ -51,16 +52,17 @@ public class McpApplication {
 	}
 
 	@Bean(destroyMethod = "close")
-	public McpClient clientSession() {
+	public McpSyncClient clientSession() {
 
 		var stdioParams = StdioServerParameters.builder("npx")
 			.args("-y", "@modelcontextprotocol/server-filesystem",
-					"/Users/christiantzolov/Dev/projects/demo/mcp-server/dir")
+					"dir")
 			.build();
 
-		McpClient mcpClient = null;
+		McpSyncClient mcpClient = null;
 		try {			
-			mcpClient = new McpClient(new StdioServerTransport(stdioParams, Duration.ofMillis(100)),
+			mcpClient = McpClient.sync(new StdioServerTransport(stdioParams,
+				Duration.ofMillis(100)),
 					Duration.ofSeconds(10), new ObjectMapper());
 
 			var init = mcpClient.initialize();

src/main/java/spring/ai/mcp/McpFunctionCallback.java

@@ -18,6 +18,7 @@ package spring.ai.mcp;
 import java.util.Map;
 
 import spring.ai.mcp.client.McpClient;
+import spring.ai.mcp.client.McpSyncClient;
 import spring.ai.mcp.spec.McpSchema.CallToolRequest;
 import spring.ai.mcp.spec.McpSchema.CallToolResult;
 import spring.ai.mcp.spec.McpSchema.Tool;
@@ -32,11 +33,12 @@ import org.springframework.ai.model.function.FunctionCallback;
 
 public class McpFunctionCallback implements FunctionCallback {
 
-	private final McpClient mcpClient;
+	// TODO: revisit function calling as well to handle the async case
+	private final McpSyncClient mcpClient;
 
 	private final Tool tool;
 
-	public McpFunctionCallback(McpClient clientSession, Tool tool) {
+	public McpFunctionCallback(McpSyncClient clientSession, Tool tool) {
 		this.mcpClient = clientSession;
 		this.tool = tool;
 	}

src/main/java/spring/ai/mcp/client/McpAsyncClient.java

@@ -0,0 +1,187 @@
+package spring.ai.mcp.client;
+
+import java.time.Duration;
+import java.util.concurrent.CompletableFuture;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import reactor.core.publisher.Mono;
+import spring.ai.mcp.spec.McpSchema;
+import spring.ai.mcp.spec.McpSession;
+import spring.ai.mcp.spec.McpTransport;
+
+public class McpAsyncClient extends McpAsyncSession {
+
+	public McpAsyncClient(McpTransport transport) {
+		this(transport, Duration.ofSeconds(10), new ObjectMapper());
+	}
+
+	public McpAsyncClient(McpTransport transport, Duration requestTimeout, ObjectMapper objectMapper) {
+		super(requestTimeout, objectMapper, transport);
+	}
+
+
+	/**
+	 * The initialization phase MUST be the first interaction between client and server.
+	 * During this phase, the client and server:
+	 * <ul>
+	 * <li>Establish protocol version compatibility</li>
+	 * <li>Exchange and negotiate capabilities</li>
+	 * <li>Share implementation details</li>
+	 * </ul>
+	 * <br/>
+	 * The client MUST initiate this phase by sending an initialize request containing:
+	 * <ul>
+	 * <li>The protocol version the client supports</li>
+	 * <li>The client's capabilities</li>
+	 * <li>Client implementation information</li>
+	 * </ul>
+	 *
+	 * The server MUST respond with its own capabilities and information:
+	 * {@link McpSchema.ServerCapabilities}. <br/>
+	 * After successful initialization, the client MUST send an initialized notification
+	 * to indicate it is ready to begin normal operations.
+	 *
+	 * <br/>
+	 *
+	 * <a href=
+	 * "https://github.com/modelcontextprotocol/specification/blob/main/docs/specification/basic/lifecycle.md#initialization">Initialization
+	 * Spec</a>
+	 * @return the initialize result.
+	 */
+	public Mono<McpSchema.InitializeResult> initialize() {
+		McpSchema.InitializeRequest initializeRequest = new McpSchema.InitializeRequest(// @formatter:off
+				McpSchema.LATEST_PROTOCOL_VERSION,
+				new McpSchema.ClientCapabilities(null, new McpSchema.ClientCapabilities.RootCapabilities(true), null),
+				new McpSchema.Implementation("mcp-java-client", "0.0.1")); // @formatter:on
+
+		Mono<McpSchema.InitializeResult> result =
+				this.sendRequest("initialize", initializeRequest, new TypeReference<McpSchema.InitializeResult>() {});
+
+		return result.flatMap(initializeResult -> {
+			if (initializeResult.protocolVersion() != McpSchema.LATEST_PROTOCOL_VERSION) {
+				return Mono.error(
+						new McpError("Unsupported protocol version from the server: "
+								+ initializeResult.protocolVersion()));
+			} else {
+				return this.sendNotification("notifications/initialized", null)
+				           .thenReturn(initializeResult);
+			}
+		});
+	}
+
+	/**
+	 * Send a roots/list_changed notification.
+	 */
+	public Mono<Void> sendRootsListChanged() {
+		return this.sendNotification("notifications/roots/list_changed");
+	}
+
+	/**
+	 * Send a synchronous ping request.
+	 */
+	public Mono<Void> ping() {
+		return this.sendRequest("ping", null,
+				new TypeReference<Void>() {});
+	}
+
+	// --------------------------
+	// Tools
+	// --------------------------
+	/**
+	 * Send a tools/call request.
+	 * @param callToolRequest the call tool request.
+	 * @return the call tool result.
+	 */
+	public Mono<McpSchema.CallToolResult> callTool(McpSchema.CallToolRequest callToolRequest) {
+		return this.sendRequest("tools/call", callToolRequest,
+				new TypeReference<McpSchema.CallToolResult>() {});
+	}
+
+	/**
+	 * Send a tools/list request.
+	 * @return the list of tools result.
+	 */
+	public Mono<McpSchema.ListToolsResult> listTools(String cursor) {
+		return this.sendRequest("tools/list", new McpSchema.PaginatedRequest(cursor),
+				new TypeReference<McpSchema.ListToolsResult>() {});
+	}
+
+	// --------------------------
+	// Resources
+	// --------------------------
+
+	/**
+	 * Send a resources/list request.
+	 * @param cursor the cursor
+	 * @return the list of resources result.
+	 */
+	public Mono<McpSchema.ListResourcesResult> listResources(String cursor) {
+		return this.sendRequest("resources/list", new McpSchema.PaginatedRequest(cursor),
+				new TypeReference<McpSchema.ListResourcesResult>() {});
+	}
+
+	/**
+	 * Send a resources/read request.
+	 * @param resource the resource to read
+	 * @return the resource content.
+	 */
+	public Mono<McpSchema.ReadResourceResult> readResource(McpSchema.Resource resource) {
+		return this.readResource(new McpSchema.ReadResourceRequest(resource.uri()));
+	}
+
+	/**
+	 * Send a resources/read request.
+	 * @param readResourceRequest the read resource request.
+	 * @return the resource content.
+	 */
+	public Mono<McpSchema.ReadResourceResult> readResource(McpSchema.ReadResourceRequest readResourceRequest) {
+		return this.sendRequest("resources/read", readResourceRequest,
+				new TypeReference<McpSchema.ReadResourceResult>() {});
+	}
+
+	/**
+	 * Resource templates allow servers to expose parameterized resources using URI
+	 * templates. Arguments may be auto-completed through the completion API.
+	 *
+	 * Request a list of resource templates the server has.
+	 * @param cursor the cursor
+	 * @return the list of resource templates result.
+	 */
+	public Mono<McpSchema.ListResourceTemplatesResult> listResourceTemplates(String cursor) {
+		return this.sendRequest("resources/templates/list", new McpSchema.PaginatedRequest(cursor),
+				new TypeReference<McpSchema.ListResourceTemplatesResult>() {});
+	}
+
+	/**
+	 * List Changed Notification. When the list of available resources changes, servers
+	 * that declared the listChanged capability SHOULD send a notification:
+	 */
+	public Mono<Void> sendResourcesListChanged() {
+		return this.sendNotification("notifications/resources/list_changed");
+	}
+
+	/**
+	 * Subscriptions. The protocol supports optional subscriptions to resource changes.
+	 * Clients can subscribe to specific resources and receive notifications when they
+	 * change.
+	 *
+	 * Send a resources/subscribe request.
+	 * @param subscribeRequest the subscribe request contains the uri of the resource to
+	 * subscribe to.
+	 */
+	public Mono<Void> subscribeResource(McpSchema.SubscribeRequest subscribeRequest) {
+		return this.sendRequest("resources/subscribe", subscribeRequest,
+				new TypeReference<Void>() {});
+	}
+
+	/**
+	 * Send a resources/unsubscribe request.
+	 * @param unsubscribeRequest the unsubscribe request contains the uri of the resource
+	 * to unsubscribe from.
+	 */
+	public Mono<Void> unsubscribeResource(McpSchema.UnsubscribeRequest unsubscribeRequest) {
+		return this.sendRequest("resources/unsubscribe", unsubscribeRequest,
+				new TypeReference<Void>() {});
+	}
+}

src/main/java/spring/ai/mcp/client/McpAsyncSession.java

@@ -0,0 +1,112 @@
+package spring.ai.mcp.client;
+
+import java.time.Duration;
+import java.util.Map;
+import java.util.UUID;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.TimeUnit;
+
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import reactor.core.publisher.Mono;
+import reactor.core.publisher.MonoSink;
+import reactor.core.publisher.Sinks;
+import spring.ai.mcp.spec.McpSchema;
+import spring.ai.mcp.spec.McpSession;
+import spring.ai.mcp.spec.McpTransport;
+
+public class McpAsyncSession {
+
+	private final ConcurrentHashMap<Object, MonoSink<McpSchema.JSONRPCResponse>> pendingResponses
+			= new ConcurrentHashMap<>();
+
+	private final Duration requestTimeout;
+
+	private final ObjectMapper objectMapper;
+
+	private final McpTransport transport;
+
+	public McpAsyncSession(Duration requestTimeout,
+			ObjectMapper objectMapper,
+			McpTransport transport) {
+		this.requestTimeout = requestTimeout;
+		this.objectMapper = objectMapper;
+		this.transport = transport;
+
+		this.transport.setMessageHandler(message -> {
+			switch (message) {
+				case McpSchema.JSONRPCResponse response -> {
+					var sink = pendingResponses.remove(response.id());
+					if (sink == null) {
+						System.out.println("Unexpected response for unkown id " + response.id());
+					} else {
+						sink.success(response);
+					}
+				}
+				case McpSchema.JSONRPCRequest request -> {
+					System.out.println("Client does not yet support server requests");
+				}
+				case McpSchema.JSONRPCNotification notification -> {
+					System.out.println("Notifications not yet supported");
+				}
+			}
+		});
+
+		this.transport.setErrorHandler(error -> System.out.println("Error received " + error));
+
+		this.transport.start();
+	}
+
+	public <T> Mono<T> sendRequest(String method, Object requestParams, TypeReference<T> typeRef) {
+		String requestId = UUID.randomUUID().toString();
+
+		return Mono.<McpSchema.JSONRPCResponse>create(sink -> {
+			this.pendingResponses.put(requestId, sink);
+			McpSchema.JSONRPCRequest jsonrpcRequest = new McpSchema.JSONRPCRequest(McpSchema.JSONRPC_VERSION, method, requestId, requestParams);
+			try {
+				// TODO convert the transport to non-blocking as well
+				this.transport.sendMessage(jsonrpcRequest);
+			} catch (Exception e) {
+				sink.error(e);
+			}
+		})
+		           .timeout(this.requestTimeout)
+		           .handle((jsonRpcResponse, s) -> {
+					   if (jsonRpcResponse.error() != null) {
+						   s.error(new McpError(jsonRpcResponse.error()));
+					   } else {
+						   s.next(this.objectMapper.convertValue(jsonRpcResponse.result(), typeRef));
+					   }
+		           });
+	}
+
+	public static class McpError extends RuntimeException {
+
+		public McpError(Object error) {
+			super(error.toString());
+		}
+	}
+
+	public Mono<Void> sendNotification(String method) {
+		return sendNotification(method, null);
+	}
+
+	public Mono<Void> sendNotification(String method, Map<String, Object> params) {
+		McpSchema.JSONRPCNotification
+				jsonrpcNotification = new McpSchema.JSONRPCNotification(McpSchema.JSONRPC_VERSION, method, params);
+		try {
+			// TODO: make it non-blocking
+			this.transport.sendMessage(jsonrpcNotification);
+		}
+		catch (Exception e) {
+			return Mono.error(new McpError(e));
+		}
+		return Mono.empty();
+	}
+
+	public Mono<Void> closeGracefully(Duration timeout) {
+		// TODO handle the timeout in transport
+		return Mono.fromRunnable(this.transport::close);
+	}
+}

src/main/java/spring/ai/mcp/client/McpClient.java

@@ -47,232 +47,35 @@ import spring.ai.mcp.spec.McpSchema.ClientCapabilities.RootCapabilities;
  * @author Christian Tzolov
  * @since 1.0.0
  */
-public class McpClient extends McpSession {
+public class McpClient {
 
-	public McpClient(McpTransport transport) {
-		this(transport, Duration.ofSeconds(10), new ObjectMapper());
+	private McpClient() {
 	}
 
-	public McpClient(McpTransport transport, Duration readTimeout, ObjectMapper objectMapper) {
-		super(transport, readTimeout, objectMapper);
+	// TODO: introduce a builder like:
+	//  McpClient.using(transport)
+	//           .withRequestTimeout(Duration.ofSeconds(5))
+	//           .withObjectMapper(objectMapper); <- or even a more sophisticated
+	//                                               JSONtoPOJOCodec type
+	//           .sync();
+
+	public static McpAsyncClient async(McpTransport transport) {
+		return new McpAsyncClient(transport);
 	}
 
-	/**
-	 * The initialization phase MUST be the first interaction between client and server.
-	 * During this phase, the client and server:
-	 * <ul>
-	 * <li>Establish protocol version compatibility</li>
-	 * <li>Exchange and negotiate capabilities</li>
-	 * <li>Share implementation details</li>
-	 * </ul>
-	 * <br/>
-	 * The client MUST initiate this phase by sending an initialize request containing:
-	 * <ul>
-	 * <li>The protocol version the client supports</li>
-	 * <li>The client's capabilities</li>
-	 * <li>Client implementation information</li>
-	 * </ul>
-	 *
-	 * The server MUST respond with its own capabilities and information:
-	 * {@link McpSchema.ServerCapabilities}. <br/>
-	 * After successful initialization, the client MUST send an initialized notification
-	 * to indicate it is ready to begin normal operations.
-	 *
-	 * <br/>
-	 *
-	 * <a href=
-	 * "https://github.com/modelcontextprotocol/specification/blob/main/docs/specification/basic/lifecycle.md#initialization">Initialization
-	 * Spec</a>
-	 * @return the initialize result.
-	 */
-	public InitializeResult initialize() {
-
-		InitializeRequest initializeRequest = new InitializeRequest(// @formatter:off
-				McpSchema.LATEST_PROTOCOL_VERSION,
-				new ClientCapabilities(null, new RootCapabilities(true), null),
-				new Implementation("mcp-java-client", "0.0.1")); // @formatter:on
-
-		CompletableFuture<InitializeResult> initializeResultFuture = this.sendRequest("initialize", initializeRequest,
-				new TypeReference<InitializeResult>() {
-				});
-
-		try {
-			InitializeResult initializeResult = initializeResultFuture.get();
-
-			if (initializeRequest.protocolVersion() != McpSchema.LATEST_PROTOCOL_VERSION) {
-				throw new McpError(
-						"Unsupported protocol version from the server: " + initializeRequest.protocolVersion());
-			}
-
-			this.sendNotification("notifications/initialized", null);
-
-			return initializeResult;
-		}
-		catch (Exception e) {
-			throw new McpError(e);
-		}
+	public static McpAsyncClient async(McpTransport transport, Duration requestTimeout,
+			ObjectMapper objectMapper) {
+		return new McpAsyncClient(transport, requestTimeout, objectMapper);
 	}
 
-	/**
-	 * Send a roots/list_changed notification.
-	 */
-	public void sendRootsListChanged() {
-		this.sendNotification("notifications/roots/list_changed");
+	public static McpSyncClient sync(McpTransport transport) {
+		return new McpSyncClient(async(transport));
 	}
 
-	/**
-	 * Send a synchronous ping request.
-	 */
-	public void ping() {
-
-		try {
-			this.sendRequest("ping", null, new TypeReference<Void>() {
-			}).get();
-		}
-		catch (Exception e) {
-			throw new McpError(e);
-		}
+	public static McpSyncClient sync(McpTransport transport, Duration requestTimeout,
+			ObjectMapper objectMapper) {
+		return new McpSyncClient(async(transport, requestTimeout, objectMapper));
 	}
 
-	// --------------------------
-	// Tools
-	// --------------------------
-	/**
-	 * Send a tools/call request.
-	 * @param callToolRequest the call tool request.
-	 * @return the call tool result.
-	 */
-	public CallToolResult callTool(CallToolRequest callToolRequest) {
-		try {
-			return this.sendRequest("tools/call", callToolRequest, new TypeReference<CallToolResult>() {
-			}).get();
-		}
-		catch (Exception e) {
-			throw new McpError(e);
-		}
-	}
 
-	/**
-	 * Send a tools/list request.
-	 * @return the list of tools result.
-	 */
-	public ListToolsResult listTools(String cursor) {
-		try {
-			return this.sendRequest("tools/list", new PaginatedRequest(cursor), new TypeReference<ListToolsResult>() {
-			}).get();
-		}
-		catch (Exception e) {
-			throw new McpError(e);
-		}
-	}
-
-	// --------------------------
-	// Resources
-	// --------------------------
-
-	/**
-	 * Send a resources/list request.
-	 * @param cursor the cursor
-	 * @return the list of resources result.
-	 */
-	public ListResourcesResult listResources(String cursor) {
-		try {
-			return this
-				.sendRequest("resources/list", new PaginatedRequest(cursor), new TypeReference<ListResourcesResult>() {
-				})
-				.get();
-		}
-		catch (Exception e) {
-			throw new McpError(e);
-		}
-	}
-
-	/**
-	 * Send a resources/read request.
-	 * @param resource the resource to read
-	 * @return the resource content.
-	 */
-	public McpSchema.ReadResourceResult readResource(Resource resource) {
-		return this.readResource(new ReadResourceRequest(resource.uri()));
-	}
-
-	/**
-	 * Send a resources/read request.
-	 * @param readResourceRequest the read resource request.
-	 * @return the resource content.
-	 */
-	public McpSchema.ReadResourceResult readResource(ReadResourceRequest readResourceRequest) {
-		try {
-			return this
-				.sendRequest("resources/read", readResourceRequest, new TypeReference<McpSchema.ReadResourceResult>() {
-				})
-				.get();
-		}
-		catch (Exception e) {
-			e.printStackTrace();
-			throw new McpError(e);
-		}
-	}
-
-	/**
-	 * Resource templates allow servers to expose parameterized resources using URI
-	 * templates. Arguments may be auto-completed through the completion API.
-	 *
-	 * Request a list of resource templates the server has.
-	 * @param cursor the cursor
-	 * @return the list of resource templates result.
-	 */
-	public ListResourceTemplatesResult listResourceTemplates(String cursor) {
-		try {
-			return this.sendRequest("resources/templates/list", new PaginatedRequest(cursor),
-					new TypeReference<ListResourceTemplatesResult>() {
-					})
-				.get();
-		}
-		catch (Exception e) {
-			throw new McpError(e);
-		}
-	}
-
-	/**
-	 * List Changed Notification. When the list of available resources changes, servers
-	 * that declared the listChanged capability SHOULD send a notification:
-	 */
-	public void sendResourcesListChanged() {
-		this.sendNotification("notifications/resources/list_changed");
-	}
-
-	/**
-	 * Subscriptions. The protocol supports optional subscriptions to resource changes.
-	 * Clients can subscribe to specific resources and receive notifications when they
-	 * change.
-	 *
-	 * Send a resources/subscribe request.
-	 * @param subscribeRequest the subscribe request contains the uri of the resource to
-	 * subscribe to.
-	 */
-	public void subscribeResource(SubscribeRequest subscribeRequest) {
-		try {
-			this.sendRequest("resources/subscribe", subscribeRequest, new TypeReference<Void>() {
-			}).get();
-		}
-		catch (Exception e) {
-			throw new McpError(e);
-		}
-	}
-
-	/**
-	 * Send a resources/unsubscribe request.
-	 * @param unsubscribeRequest the unsubscribe request contains the uri of the resource
-	 * to unsubscribe from.
-	 */
-	public void unsubscribeResource(UnsubscribeRequest unsubscribeRequest) {
-		try {
-			this.sendRequest("resources/unsubscribe", unsubscribeRequest, new TypeReference<Void>() {
-			}).get();
-		}
-		catch (Exception e) {
-			throw new McpError(e);
-		}
-	}
 }

src/main/java/spring/ai/mcp/client/McpSyncClient.java

@@ -0,0 +1,177 @@
+package spring.ai.mcp.client;
+
+import java.time.Duration;
+
+import spring.ai.mcp.spec.McpSchema;
+
+public class McpSyncClient implements AutoCloseable {
+
+	// TODO: Consider providing a client config to set this properly
+	//  this is currently a concern only because AutoCloseable is used - perhaps it is
+	//  not a requirement?
+	private static final long DEFAULT_CLOSE_TIMEOUT_MS = 10_000L;
+
+	McpAsyncClient delegate;
+
+	public McpSyncClient(McpAsyncClient delegate) {
+		this.delegate = delegate;
+	}
+
+	@Override
+	public void close() {
+		delegate.closeGracefully(Duration.ofMillis(DEFAULT_CLOSE_TIMEOUT_MS)).block();
+	}
+
+	/**
+	 * The initialization phase MUST be the first interaction between client and server.
+	 * During this phase, the client and server:
+	 * <ul>
+	 * <li>Establish protocol version compatibility</li>
+	 * <li>Exchange and negotiate capabilities</li>
+	 * <li>Share implementation details</li>
+	 * </ul>
+	 * <br/>
+	 * The client MUST initiate this phase by sending an initialize request containing:
+	 * <ul>
+	 * <li>The protocol version the client supports</li>
+	 * <li>The client's capabilities</li>
+	 * <li>Client implementation information</li>
+	 * </ul>
+	 *
+	 * The server MUST respond with its own capabilities and information:
+	 * {@link McpSchema.ServerCapabilities}. <br/>
+	 * After successful initialization, the client MUST send an initialized notification
+	 * to indicate it is ready to begin normal operations.
+	 *
+	 * <br/>
+	 *
+	 * <a href=
+	 * "https://github.com/modelcontextprotocol/specification/blob/main/docs/specification/basic/lifecycle.md#initialization">Initialization
+	 * Spec</a>
+	 * @return the initialize result.
+	 */
+	public McpSchema.InitializeResult initialize() {
+		// TODO: block takes no argument here as we assume the async client is
+		//  configured with a requestTimeout at all times
+		return delegate.initialize()
+		               .block();
+	}
+
+	/**
+	 * Send a roots/list_changed notification.
+	 */
+	public void sendRootsListChanged() {
+		delegate.sendRootsListChanged()
+		        .block();
+	}
+
+	/**
+	 * Send a synchronous ping request.
+	 */
+	public void ping() {
+		delegate.ping()
+		        .block();
+	}
+
+	// --------------------------
+	// Tools
+	// --------------------------
+	/**
+	 * Send a tools/call request.
+	 * @param callToolRequest the call tool request.
+	 * @return the call tool result.
+	 */
+	public McpSchema.CallToolResult callTool(McpSchema.CallToolRequest callToolRequest) {
+		return delegate.callTool(callToolRequest)
+		               .block();
+	}
+
+	/**
+	 * Send a tools/list request.
+	 * @return the list of tools result.
+	 */
+	public McpSchema.ListToolsResult listTools(String cursor) {
+		return delegate.listTools(cursor)
+				.block();
+	}
+
+	// --------------------------
+	// Resources
+	// --------------------------
+
+	/**
+	 * Send a resources/list request.
+	 * @param cursor the cursor
+	 * @return the list of resources result.
+	 */
+	public McpSchema.ListResourcesResult listResources(String cursor) {
+		return delegate.listResources(cursor)
+				.block();
+	}
+
+	/**
+	 * Send a resources/read request.
+	 * @param resource the resource to read
+	 * @return the resource content.
+	 */
+	public McpSchema.ReadResourceResult readResource(McpSchema.Resource resource) {
+		return delegate.readResource(resource)
+				.block();
+	}
+
+	/**
+	 * Send a resources/read request.
+	 * @param readResourceRequest the read resource request.
+	 * @return the resource content.
+	 */
+	public McpSchema.ReadResourceResult readResource(McpSchema.ReadResourceRequest readResourceRequest) {
+		return delegate.readResource(readResourceRequest)
+				.block();
+	}
+
+	/**
+	 * Resource templates allow servers to expose parameterized resources using URI
+	 * templates. Arguments may be auto-completed through the completion API.
+	 *
+	 * Request a list of resource templates the server has.
+	 * @param cursor the cursor
+	 * @return the list of resource templates result.
+	 */
+	public McpSchema.ListResourceTemplatesResult listResourceTemplates(String cursor) {
+		return delegate.listResourceTemplates(cursor)
+				.block();
+	}
+
+	/**
+	 * List Changed Notification. When the list of available resources changes, servers
+	 * that declared the listChanged capability SHOULD send a notification:
+	 */
+	public void sendResourcesListChanged() {
+		delegate.sendResourcesListChanged()
+				.block();
+	}
+
+	/**
+	 * Subscriptions. The protocol supports optional subscriptions to resource changes.
+	 * Clients can subscribe to specific resources and receive notifications when they
+	 * change.
+	 *
+	 * Send a resources/subscribe request.
+	 * @param subscribeRequest the subscribe request contains the uri of the resource to
+	 * subscribe to.
+	 */
+	public void subscribeResource(McpSchema.SubscribeRequest subscribeRequest) {
+		delegate.subscribeResource(subscribeRequest)
+				.block();
+	}
+
+	/**
+	 * Send a resources/unsubscribe request.
+	 * @param unsubscribeRequest the unsubscribe request contains the uri of the resource
+	 * to unsubscribe from.
+	 */
+	public void unsubscribeResource(McpSchema.UnsubscribeRequest unsubscribeRequest) {
+		delegate.unsubscribeResource(unsubscribeRequest)
+				.block();
+	}
+}

src/test/java/spring/ai/mcp/ClientSessionTests.java

@@ -19,6 +19,7 @@ import java.time.Duration;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 import spring.ai.mcp.client.McpClient;
+import spring.ai.mcp.client.McpSyncClient;
 import spring.ai.mcp.client.stdio.StdioServerParameters;
 import spring.ai.mcp.client.stdio.StdioServerTransport;
 import spring.ai.mcp.spec.McpSchema.ListResourcesResult;
@@ -33,10 +34,12 @@ public class ClientSessionTests {
 
 		var stdioParams = StdioServerParameters.builder("npx")
 			.args("-y", "@modelcontextprotocol/server-everything",
-					"/Users/christiantzolov/Dev/projects/demo/mcp-server/dir")
+					"dir")
 			.build();
 
-		try (McpClient clientSession = new McpClient(new StdioServerTransport(stdioParams), Duration.ofSeconds(10),
+		try (McpSyncClient clientSession =
+				     McpClient.sync(new StdioServerTransport(stdioParams),
+				Duration.ofSeconds(10),
 				new ObjectMapper())) {
 			// clientSession.handleIncomingMessages();
 			clientSession.initialize();

src/test/java/spring/ai/mcp/ClientSessionTests2.java

@@ -19,6 +19,7 @@ import java.time.Duration;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 import spring.ai.mcp.client.McpClient;
+import spring.ai.mcp.client.McpSyncClient;
 import spring.ai.mcp.client.stdio.StdioServerParameters;
 import spring.ai.mcp.client.stdio.StdioServerTransport;
 import spring.ai.mcp.spec.McpSchema.ListResourcesResult;
@@ -34,11 +35,13 @@ public class ClientSessionTests2 {
 	public static void main(String[] args) {
 
 		var stdioParams = StdioServerParameters.builder("uv")
-			.args("--directory", "/Users/christiantzolov/Dev/projects/demo/mcp-server/dir", "run", "mcp-server-sqlite",
+			.args("--directory", "dir", "run", "mcp-server-sqlite",
 					"--db-path", "~/test.db")
 			.build();
 
-		try (McpClient clientSession = new McpClient(new StdioServerTransport(stdioParams), Duration.ofSeconds(10), new ObjectMapper())) {
+		try (McpSyncClient clientSession =
+				     McpClient.sync(new StdioServerTransport(stdioParams),
+						     Duration.ofSeconds(10), new ObjectMapper())) {
 
 			clientSession.initialize();
 

src/test/java/spring/ai/mcp/ClientSessionTests3.java

@@ -19,6 +19,7 @@ import java.time.Duration;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 import spring.ai.mcp.client.McpClient;
+import spring.ai.mcp.client.McpSyncClient;
 import spring.ai.mcp.client.stdio.StdioServerParameters;
 import spring.ai.mcp.client.stdio.StdioServerTransport;
 import spring.ai.mcp.spec.McpSchema.ListResourcesResult;
@@ -34,15 +35,16 @@ public class ClientSessionTests3 {
 	public static void main(String[] args) {
 
 		var stdioParams = StdioServerParameters.builder("uv")
-			.args("--directory", "/Users/christiantzolov/Dev/projects/demo/mcp-server/dir", "run", "mcp-server-sqlite",
+			.args("--directory", "dir", "run", "mcp-server-sqlite",
 					"--db-path", "~/test.db")
 			.build();
 
-	
-		McpClient clientSession = null;
+
+		McpSyncClient clientSession = null;
 		try {
 
-			clientSession = new McpClient(new StdioServerTransport(stdioParams), Duration.ofSeconds(10), new ObjectMapper());
+			clientSession = McpClient.sync(new StdioServerTransport(stdioParams),
+				Duration.ofSeconds(10), new ObjectMapper());
 
 			clientSession.initialize();