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Move mcp-spring-webflux and mcp-spring-webmvc to Spring AI 2.0 (#805)

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The Spring-specific transport modules (mcp-spring-webflux,
mcp-spring-webmvc) have been moved out of the MCP Java SDK into the
Spring AI project (org.springframework.ai group), effective with
MCP Java SDK 1.0 and Spring AI 2.0. This is a breaking change.

- Delete mcp-spring-webflux and mcp-spring-webmvc source modules
- Remove both artifacts from mcp-bom and root pom.xml module list
- Update docs and README
- Add blog post explaining the breaking change with before/after
  migration examples

Resolves: #127

Signed-off-by: Christian Tzolov <christian.tzolov@broadcom.com>
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Christian Tzolov 2026-02-20 15:39:36 +01:00 • committed by GitHub
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@ -1,5 +1,5 @@
---
title: Overview
title: Index
description: Introduction to the Model Context Protocol (MCP) Java SDK
---
@ -27,7 +27,7 @@ enables standardized integration between AI models and tools.
- Java HttpClient-based SSE client transport for HTTP SSE Client-side streaming
- Servlet-based SSE server transport for HTTP SSE Server streaming
- [Streamable HTTP](https://modelcontextprotocol.io/specification/2025-11-25/basic/transports#streamable-http) transport for efficient bidirectional communication (client and server)
- Optional Spring-based transports (convenience if using Spring Framework):
- Optional Spring-based transports (available in [Spring AI](https://docs.spring.io/spring-ai/reference/2.0-SNAPSHOT/api/mcp/mcp-overview.html) 2.0+, no longer part of this SDK):
- WebFlux SSE client and server transports for reactive HTTP streaming
- WebFlux Streamable HTTP server transport
- WebMVC SSE server transport for servlet-based HTTP streaming
@ -41,56 +41,9 @@ enables standardized integration between AI models and tools.
!!! tip
The core `io.modelcontextprotocol.sdk:mcp` module provides default STDIO, SSE, and Streamable HTTP client and server transport implementations without requiring external web frameworks.
Spring-specific transports are available as optional dependencies for convenience when using the [MCP Client Boot Starter](https://docs.spring.io/spring-ai/reference/api/mcp/mcp-client-boot-starter-docs.html) and [MCP Server Boot Starter](https://docs.spring.io/spring-ai/reference/api/mcp/mcp-server-boot-starter-docs.html).
Also consider the [MCP Annotations](https://docs.spring.io/spring-ai/reference/api/mcp/mcp-annotations-overview.html) and [MCP Security](https://docs.spring.io/spring-ai/reference/api/mcp/mcp-security.html).
## Architecture
The SDK follows a layered architecture with clear separation of concerns:
![MCP Stack Architecture](images/mcp-stack.svg)
- **Client/Server Layer (McpClient/McpServer)**: Both use McpSession for sync/async operations,
with McpClient handling client-side protocol operations and McpServer managing server-side protocol operations.
- **Session Layer (McpSession)**: Manages communication patterns and state.
- **Transport Layer (McpTransport)**: Handles JSON-RPC message serialization/deserialization via:
- StdioTransport (stdin/stdout) in the core module
- HTTP SSE transports in dedicated transport modules (Java HttpClient, Spring WebFlux, Spring WebMVC)
- Streamable HTTP transports for efficient bidirectional communication
The MCP Client is a key component in the Model Context Protocol (MCP) architecture, responsible for establishing and managing connections with MCP servers.
It implements the client-side of the protocol.
![Java MCP Client Architecture](images/java-mcp-client-architecture.jpg)
The MCP Server is a foundational component in the Model Context Protocol (MCP) architecture that provides tools, resources, and capabilities to clients.
It implements the server-side of the protocol.
![Java MCP Server Architecture](images/java-mcp-server-architecture.jpg)
Key Interactions:
- **Client/Server Initialization**: Transport setup, protocol compatibility check, capability negotiation, and implementation details exchange.
- **Message Flow**: JSON-RPC message handling with validation, type-safe response processing, and error handling.
- **Resource Management**: Resource discovery, URI template-based access, subscription system, and content retrieval.
## Module Structure
The SDK is organized into modules to separate concerns and allow adopters to bring in only what they need:
| Module | Artifact ID | Purpose |
|--------|------------|---------|
| `mcp-bom` | `mcp-bom` | Bill of Materials for dependency management |
| `mcp-core` | `mcp-core` | Core reference implementation (STDIO, JDK HttpClient, Servlet, Streamable HTTP) |
| `mcp-json-jackson2` | `mcp-json-jackson2` | Jackson 2.x JSON serialization implementation |
| `mcp-json-jackson3` | `mcp-json-jackson3` | Jackson 3.x JSON serialization implementation |
| `mcp` | `mcp` | Convenience bundle (`mcp-core` + `mcp-json-jackson3`) |
| `mcp-test` | `mcp-test` | Shared testing utilities and integration tests |
| `mcp-spring-webflux` | `mcp-spring-webflux` | Spring WebFlux integration (SSE and Streamable HTTP) |
| `mcp-spring-webmvc` | `mcp-spring-webmvc` | Spring WebMVC integration (SSE and Streamable HTTP) |
!!! tip
A minimal adopter may depend only on `mcp` (core + Jackson 3), while a Spring-based application can add `mcp-spring-webflux` or `mcp-spring-webmvc` for deeper framework integration.
Spring-specific transports (WebFlux, WebMVC) are now part of [Spring AI](https://docs.spring.io/spring-ai/reference/2.0-SNAPSHOT/api/mcp/mcp-overview.html) 2.0+ and are no longer shipped by this SDK.
Use the [MCP Client Boot Starter](https://docs.spring.io/spring-ai/reference/2.0-SNAPSHOT/api/mcp/mcp-client-boot-starter-docs.html) and [MCP Server Boot Starter](https://docs.spring.io/spring-ai/reference/2.0-SNAPSHOT/api/mcp/mcp-server-boot-starter-docs.html) from Spring AI.
Also consider the [MCP Annotations](https://docs.spring.io/spring-ai/reference/2.0-SNAPSHOT/api/mcp/mcp-annotations-overview.html) and [MCP Security](https://docs.spring.io/spring-ai/reference/2.0-SNAPSHOT/api/mcp/mcp-security.html).
## Next Steps