feat: HttpServlet Streamable HTTP server implementation (#290)

Implementation of the Streamable HTTP transport provider for the Servlet API.

---
Signed-off-by: Christian Tzolov <christian.tzolov@broadcom.com>
Co-authored-by: Christian Tzolov <christian.tzolov@broadcom.com>
Co-authored-by: Zachary German <zdgerman@amazon.com>

mcp/src/test/java/io/modelcontextprotocol/server/HttpServletStreamableAsyncServerTests.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2024-2024 the original author or authors.
+ */
+
+package io.modelcontextprotocol.server;
+
+import org.junit.jupiter.api.Timeout;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import io.modelcontextprotocol.server.transport.HttpServletStreamableServerTransportProvider;
+import io.modelcontextprotocol.spec.McpStreamableServerTransportProvider;
+
+/**
+ * Tests for {@link McpAsyncServer} using
+ * {@link HttpServletStreamableServerTransportProvider}.
+ *
+ * @author Christian Tzolov
+ */
+@Timeout(15)
+class HttpServletStreamableAsyncServerTests extends AbstractMcpAsyncServerTests {
+
+	protected McpStreamableServerTransportProvider createMcpTransportProvider() {
+		return HttpServletStreamableServerTransportProvider.builder()
+			.objectMapper(new ObjectMapper())
+			.mcpEndpoint("/mcp/message")
+			.build();
+	}
+
+	@Override
+	protected McpServer.AsyncSpecification<?> prepareAsyncServerBuilder() {
+		return McpServer.async(createMcpTransportProvider());
+	}
+
+}

mcp/src/test/java/io/modelcontextprotocol/server/HttpServletStreamableIntegrationTests.java

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+/*
+ * Copyright 2024 - 2024 the original author or authors.
+ */
+package io.modelcontextprotocol.server;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.time.Duration;
+
+import org.apache.catalina.LifecycleException;
+import org.apache.catalina.LifecycleState;
+import org.apache.catalina.startup.Tomcat;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import io.modelcontextprotocol.client.McpClient;
+import io.modelcontextprotocol.client.transport.HttpClientStreamableHttpTransport;
+import io.modelcontextprotocol.server.McpServer.AsyncSpecification;
+import io.modelcontextprotocol.server.McpServer.SyncSpecification;
+import io.modelcontextprotocol.server.transport.HttpServletStreamableServerTransportProvider;
+import io.modelcontextprotocol.server.transport.TomcatTestUtil;
+
+class HttpServletStreamableIntegrationTests extends AbstractMcpClientServerIntegrationTests {
+
+	private static final int PORT = TomcatTestUtil.findAvailablePort();
+
+	private static final String MESSAGE_ENDPOINT = "/mcp/message";
+
+	private HttpServletStreamableServerTransportProvider mcpServerTransportProvider;
+
+	private Tomcat tomcat;
+
+	@BeforeEach
+	public void before() {
+		// Create and configure the transport provider
+		mcpServerTransportProvider = HttpServletStreamableServerTransportProvider.builder()
+			.objectMapper(new ObjectMapper())
+			.mcpEndpoint(MESSAGE_ENDPOINT)
+			.build();
+
+		tomcat = TomcatTestUtil.createTomcatServer("", PORT, mcpServerTransportProvider);
+		try {
+			tomcat.start();
+			assertThat(tomcat.getServer().getState()).isEqualTo(LifecycleState.STARTED);
+		}
+		catch (Exception e) {
+			throw new RuntimeException("Failed to start Tomcat", e);
+		}
+
+		clientBuilders
+			.put("httpclient",
+					McpClient.sync(HttpClientStreamableHttpTransport.builder("http://localhost:" + PORT)
+						.endpoint(MESSAGE_ENDPOINT)
+						.build()).initializationTimeout(Duration.ofHours(10)).requestTimeout(Duration.ofHours(10)));
+	}
+
+	@Override
+	protected AsyncSpecification<?> prepareAsyncServerBuilder() {
+		return McpServer.async(this.mcpServerTransportProvider);
+	}
+
+	@Override
+	protected SyncSpecification<?> prepareSyncServerBuilder() {
+		return McpServer.sync(this.mcpServerTransportProvider);
+	}
+
+	@AfterEach
+	public void after() {
+		if (mcpServerTransportProvider != null) {
+			mcpServerTransportProvider.closeGracefully().block();
+		}
+		if (tomcat != null) {
+			try {
+				tomcat.stop();
+				tomcat.destroy();
+			}
+			catch (LifecycleException e) {
+				throw new RuntimeException("Failed to stop Tomcat", e);
+			}
+		}
+	}
+
+	@Override
+	protected void prepareClients(int port, String mcpEndpoint) {
+	}
+
+}

mcp/src/test/java/io/modelcontextprotocol/server/HttpServletStreamableSyncServerTests.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2024-2024 the original author or authors.
+ */
+
+package io.modelcontextprotocol.server;
+
+import org.junit.jupiter.api.Timeout;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import io.modelcontextprotocol.server.transport.HttpServletStreamableServerTransportProvider;
+import io.modelcontextprotocol.spec.McpStreamableServerTransportProvider;
+
+/**
+ * Tests for {@link McpSyncServer} using
+ * {@link HttpServletStreamableServerTransportProvider}.
+ *
+ * @author Christian Tzolov
+ */
+@Timeout(15)
+class HttpServletStreamableSyncServerTests extends AbstractMcpSyncServerTests {
+
+	protected McpStreamableServerTransportProvider createMcpTransportProvider() {
+		return HttpServletStreamableServerTransportProvider.builder()
+			.objectMapper(new ObjectMapper())
+			.mcpEndpoint("/mcp/message")
+			.build();
+	}
+
+	@Override
+	protected McpServer.SyncSpecification<?> prepareSyncServerBuilder() {
+		return McpServer.sync(createMcpTransportProvider());
+	}
+
+}