Introduce McpJsonMapper interface to decouple from Jackson

mcp-bom/pom.xml

@@ -33,6 +33,20 @@
                 <version>${project.version}</version>
             </dependency>
 
+            <!-- MCP JSON -->
+            <dependency>
+                <groupId>io.modelcontextprotocol.sdk</groupId>
+                <artifactId>mcp-json</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+
+            <!-- MCP JSON Jackson -->
+            <dependency>
+                <groupId>io.modelcontextprotocol.sdk</groupId>
+                <artifactId>mcp-json-jackson2</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+
             <!-- MCP Test -->
             <dependency>
                 <groupId>io.modelcontextprotocol.sdk</groupId>

mcp-json-jackson2/pom.xml

@@ -0,0 +1,53 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<parent>
+		<groupId>io.modelcontextprotocol.sdk</groupId>
+		<artifactId>mcp-parent</artifactId>
+		<version>0.13.0-SNAPSHOT</version>
+	</parent>
+	<artifactId>mcp-json-jackson2</artifactId>
+	<packaging>jar</packaging>
+	<name>Java MCP SDK JSON Jackson</name>
+	<description>Java MCP SDK JSON implementation based on Jackson</description>
+	<url>https://github.com/modelcontextprotocol/java-sdk</url>
+	<scm>
+		<url>https://github.com/modelcontextprotocol/java-sdk</url>
+		<connection>git://github.com/modelcontextprotocol/java-sdk.git</connection>
+		<developerConnection>git@github.com/modelcontextprotocol/java-sdk.git</developerConnection>
+	</scm>
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-jar-plugin</artifactId>
+				<configuration>
+					<archive>
+                        <manifest>
+                            <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
+                        </manifest>
+					</archive>
+				</configuration>
+			</plugin>
+		</plugins>
+	</build>
+	<dependencies>
+        <dependency>
+            <groupId>io.modelcontextprotocol.sdk</groupId>
+            <artifactId>mcp-json</artifactId>
+            <version>0.13.0-SNAPSHOT</version>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.networknt</groupId>
+            <artifactId>json-schema-validator</artifactId>
+            <version>${json-schema-validator.version}</version>
+        </dependency>
+	</dependencies>
+</project>

mcp-json-jackson2/src/main/java/io/modelcontextprotocol/json/jackson/JacksonMcpJsonMapper.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2025 - 2025 the original author or authors.
+ */
+package io.modelcontextprotocol.json.jackson;
+
+import com.fasterxml.jackson.databind.JavaType;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import io.modelcontextprotocol.json.McpJsonMapper;
+import io.modelcontextprotocol.json.TypeRef;
+
+import java.io.IOException;
+
+/**
+ * Jackson-based implementation of JsonMapper. Wraps a Jackson ObjectMapper but keeps the
+ * SDK decoupled from Jackson at the API level.
+ */
+public final class JacksonMcpJsonMapper implements McpJsonMapper {
+
+	private final ObjectMapper objectMapper;
+
+	/**
+	 * Constructs a new JacksonMcpJsonMapper instance with the given ObjectMapper.
+	 * @param objectMapper the ObjectMapper to be used for JSON serialization and
+	 * deserialization. Must not be null.
+	 * @throws IllegalArgumentException if the provided ObjectMapper is null.
+	 */
+	public JacksonMcpJsonMapper(ObjectMapper objectMapper) {
+		if (objectMapper == null) {
+			throw new IllegalArgumentException("ObjectMapper must not be null");
+		}
+		this.objectMapper = objectMapper;
+	}
+
+	/**
+	 * Returns the underlying Jackson {@link ObjectMapper} used for JSON serialization and
+	 * deserialization.
+	 * @return the ObjectMapper instance
+	 */
+	public ObjectMapper getObjectMapper() {
+		return objectMapper;
+	}
+
+	@Override
+	public <T> T readValue(String content, Class<T> type) throws IOException {
+		return objectMapper.readValue(content, type);
+	}
+
+	@Override
+	public <T> T readValue(byte[] content, Class<T> type) throws IOException {
+		return objectMapper.readValue(content, type);
+	}
+
+	@Override
+	public <T> T readValue(String content, TypeRef<T> type) throws IOException {
+		JavaType javaType = objectMapper.getTypeFactory().constructType(type.getType());
+		return objectMapper.readValue(content, javaType);
+	}
+
+	@Override
+	public <T> T readValue(byte[] content, TypeRef<T> type) throws IOException {
+		JavaType javaType = objectMapper.getTypeFactory().constructType(type.getType());
+		return objectMapper.readValue(content, javaType);
+	}
+
+	@Override
+	public <T> T convertValue(Object fromValue, Class<T> type) {
+		return objectMapper.convertValue(fromValue, type);
+	}
+
+	@Override
+	public <T> T convertValue(Object fromValue, TypeRef<T> type) {
+		JavaType javaType = objectMapper.getTypeFactory().constructType(type.getType());
+		return objectMapper.convertValue(fromValue, javaType);
+	}
+
+	@Override
+	public String writeValueAsString(Object value) throws IOException {
+		return objectMapper.writeValueAsString(value);
+	}
+
+	@Override
+	public byte[] writeValueAsBytes(Object value) throws IOException {
+		return objectMapper.writeValueAsBytes(value);
+	}
+
+}

mcp-json-jackson2/src/main/java/io/modelcontextprotocol/json/jackson/JacksonMcpJsonMapperSupplier.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2025 - 2025 the original author or authors.
+ */
+package io.modelcontextprotocol.json.jackson;
+
+import io.modelcontextprotocol.json.McpJsonMapper;
+import io.modelcontextprotocol.json.McpJsonMapperSupplier;
+
+/**
+ * A supplier of {@link McpJsonMapper} instances that uses the Jackson library for JSON
+ * serialization and deserialization.
+ * <p>
+ * This implementation provides a {@link McpJsonMapper} backed by a Jackson
+ * {@link com.fasterxml.jackson.databind.ObjectMapper}.
+ */
+public class JacksonMcpJsonMapperSupplier implements McpJsonMapperSupplier {
+
+	/**
+	 * Returns a new instance of {@link McpJsonMapper} that uses the Jackson library for
+	 * JSON serialization and deserialization.
+	 * <p>
+	 * The returned {@link McpJsonMapper} is backed by a new instance of
+	 * {@link com.fasterxml.jackson.databind.ObjectMapper}.
+	 * @return a new {@link McpJsonMapper} instance
+	 */
+	@Override
+	public McpJsonMapper get() {
+		return new JacksonMcpJsonMapper(new com.fasterxml.jackson.databind.ObjectMapper());
+	}
+
+}

mcp/src/main/java/io/modelcontextprotocol/spec/DefaultJsonSchemaValidator.java → mcp-json-jackson2/src/main/java/io/modelcontextprotocol/json/schema/jackson/DefaultJsonSchemaValidator.java

@@ -1,13 +1,13 @@
 /*
  * Copyright 2024-2024 the original author or authors.
  */
-
-package io.modelcontextprotocol.spec;
+package io.modelcontextprotocol.json.schema.jackson;
 
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
+import io.modelcontextprotocol.json.schema.JsonSchemaValidator;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -20,8 +20,6 @@
 import com.networknt.schema.SpecVersion;
 import com.networknt.schema.ValidationMessage;
 
-import io.modelcontextprotocol.util.Assert;
-
 /**
  * Default implementation of the {@link JsonSchemaValidator} interface. This class
  * provides methods to validate structured content against a JSON schema. It uses the
@@ -52,9 +50,12 @@ public DefaultJsonSchemaValidator(ObjectMapper objectMapper) {
 
 	@Override
 	public ValidationResponse validate(Map<String, Object> schema, Map<String, Object> structuredContent) {
-
-		Assert.notNull(schema, "Schema must not be null");
-		Assert.notNull(structuredContent, "Structured content must not be null");
+		if (schema == null) {
+			throw new IllegalArgumentException("Schema must not be null");
+		}
+		if (structuredContent == null) {
+			throw new IllegalArgumentException("Structured content must not be null");
+		}
 
 		try {
 

mcp-json-jackson2/src/main/java/io/modelcontextprotocol/json/schema/jackson/JacksonJsonSchemaValidatorSupplier.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2025 - 2025 the original author or authors.
+ */
+package io.modelcontextprotocol.json.schema.jackson;
+
+import io.modelcontextprotocol.json.schema.JsonSchemaValidator;
+import io.modelcontextprotocol.json.schema.JsonSchemaValidatorSupplier;
+
+/**
+ * A concrete implementation of {@link JsonSchemaValidatorSupplier} that provides a
+ * {@link JsonSchemaValidator} instance based on the Jackson library.
+ *
+ * @see JsonSchemaValidatorSupplier
+ * @see JsonSchemaValidator
+ */
+public class JacksonJsonSchemaValidatorSupplier implements JsonSchemaValidatorSupplier {
+
+	/**
+	 * Returns a new instance of {@link JsonSchemaValidator} that uses the Jackson library
+	 * for JSON schema validation.
+	 * @return A {@link JsonSchemaValidator} instance.
+	 */
+	@Override
+	public JsonSchemaValidator get() {
+		return new DefaultJsonSchemaValidator();
+	}
+
+}

mcp-json-jackson2/src/main/resources/META-INF/services/io.modelcontextprotocol.json.McpJsonMapperSupplier

@@ -0,0 +1 @@
+io.modelcontextprotocol.json.jackson.JacksonMcpJsonMapperSupplier

mcp-json-jackson2/src/main/resources/META-INF/services/io.modelcontextprotocol.json.schema.JsonSchemaValidatorSupplier

@@ -0,0 +1 @@
+io.modelcontextprotocol.json.schema.jackson.JacksonJsonSchemaValidatorSupplier

mcp-json/pom.xml

@@ -0,0 +1,39 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<parent>
+		<groupId>io.modelcontextprotocol.sdk</groupId>
+		<artifactId>mcp-parent</artifactId>
+		<version>0.13.0-SNAPSHOT</version>
+	</parent>
+	<artifactId>mcp-json</artifactId>
+	<packaging>jar</packaging>
+	<name>Java MCP SDK JSON Support</name>
+	<description>Java MCP SDK JSON Support API</description>
+	<url>https://github.com/modelcontextprotocol/java-sdk</url>
+	<scm>
+		<url>https://github.com/modelcontextprotocol/java-sdk</url>
+		<connection>git://github.com/modelcontextprotocol/java-sdk.git</connection>
+		<developerConnection>git@github.com/modelcontextprotocol/java-sdk.git</developerConnection>
+	</scm>
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-jar-plugin</artifactId>
+				<configuration>
+					<archive>
+                        <manifest>
+                            <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
+                        </manifest>
+					</archive>
+				</configuration>
+			</plugin>
+		</plugins>
+	</build>
+	<dependencies>
+
+    </dependencies>
+</project>

mcp-json/src/main/java/io/modelcontextprotocol/json/McpJsonInternal.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2025 - 2025 the original author or authors.
+ */
+package io.modelcontextprotocol.json;
+
+import java.util.ServiceLoader;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.stream.Stream;
+
+/**
+ * Utility class for creating a default {@link McpJsonMapper} instance. This class
+ * provides a single method to create a default mapper using the {@link ServiceLoader}
+ * mechanism.
+ */
+final class McpJsonInternal {
+
+	private static McpJsonMapper defaultJsonMapper = null;
+
+	/**
+	 * Returns the cached default {@link McpJsonMapper} instance. If the default mapper
+	 * has not been created yet, it will be initialized using the
+	 * {@link #createDefaultMapper()} method.
+	 * @return the default {@link McpJsonMapper} instance
+	 * @throws IllegalStateException if no default {@link McpJsonMapper} implementation is
+	 * found
+	 */
+	static McpJsonMapper getDefaultMapper() {
+		if (defaultJsonMapper == null) {
+			defaultJsonMapper = McpJsonInternal.createDefaultMapper();
+		}
+		return defaultJsonMapper;
+	}
+
+	/**
+	 * Creates a default {@link McpJsonMapper} instance using the {@link ServiceLoader}
+	 * mechanism. The default mapper is resolved by loading the first available
+	 * {@link McpJsonMapperSupplier} implementation on the classpath.
+	 * @return the default {@link McpJsonMapper} instance
+	 * @throws IllegalStateException if no default {@link McpJsonMapper} implementation is
+	 * found
+	 */
+	static McpJsonMapper createDefaultMapper() {
+		AtomicReference<IllegalStateException> ex = new AtomicReference<>();
+		return ServiceLoader.load(McpJsonMapperSupplier.class).stream().flatMap(p -> {
+			try {
+				McpJsonMapperSupplier supplier = p.get();
+				return Stream.ofNullable(supplier);
+			}
+			catch (Exception e) {
+				addException(ex, e);
+				return Stream.empty();
+			}
+		}).flatMap(jsonMapperSupplier -> {
+			try {
+				return Stream.ofNullable(jsonMapperSupplier.get());
+			}
+			catch (Exception e) {
+				addException(ex, e);
+				return Stream.empty();
+			}
+		}).findFirst().orElseThrow(() -> {
+			if (ex.get() != null) {
+				return ex.get();
+			}
+			else {
+				return new IllegalStateException("No default McpJsonMapper implementation found");
+			}
+		});
+	}
+
+	private static void addException(AtomicReference<IllegalStateException> ref, Exception toAdd) {
+		ref.updateAndGet(existing -> {
+			if (existing == null) {
+				return new IllegalStateException("Failed to initialize default McpJsonMapper", toAdd);
+			}
+			else {
+				existing.addSuppressed(toAdd);
+				return existing;
+			}
+		});
+	}
+
+}