mcp_mediator

MCP Mediator – Automatic MCP Server Generation

A Java-based implementation of a Model Context Protocol (MCP) mediator that automatically generates an MCP Server from existing source code, service classes, helper methods, and external MCP tools. The MCP Mediator aggregates these diverse components into a unified MCP Server, streamlining communication between MCP clients and servers through a single point.

By eliminating the need to manually maintain multiple MCP Servers, this tool simplifies integration and execution within the MCP ecosystem and make it possible to generate MCP Servers without altering the existing code bases and tools that are planned to be MCP compatible.

MCP Mediator High Level Diagram MCP Mediator High Level Diagram

Overview

The MCP Mediator implements the Model Context Protocol specification, providing a robust framework for:

For more information, visit the project’s wiki: MCP Mediator Wiki. Wiki page is organized as follows:

Features

:white_check_mark: Ready:

:hourglass_flowing_sand: Work In Progress:

:baby_bottle: Planned:

Modules

Getting Started

Prerequisites

All the examples are available under mcp-mediator-exmple module. It’s still a work in progress and the examples will be added.

Default MCP Mediator

To create a MCP Mediator with STDIO transport:

DefaultMcpMediator mediator = new DefaultMcpMediator(McpMediatorConfigurationBuilder.builder()
          .createDefault()
          .serverName(MY_EXAMPLE_MCP_SERVER_STDIO)
          .build());
mediator.registerHandler(new WikipediaQueryRequestHandler());
mediator.initialize();

To run the examples as Claude Desktop MCP Server:

{
  "mcpServers": {
    "my_java_mcp_server": {
      "command": "[path to]/run.sh",
      "args": [
        "DefaultMcpMediatorStdioExample"
      ]
    }
  }
}

This config runs DefaultMcpMediatorStdioExample sa STDIO MCP server. Make sure to make run.sh executable and add mvn command to your path.

 ./run.sh ClassName [arg1 arg2 ...]

This mediator runs a STDIO MCP server with handlers and delegates requests from MCP client (e.g. Claude Desktop) to the registered handlers.

Convert Existing Code to MCP Server

Convert the existing code, service, helper class, or method automatically to an MCP server using @McpService:

DefaultMcpMediator mediator = new DefaultMcpMediator(McpMediatorConfigurationBuilder.builder()
                .createDefault()
                .serverName(MY_EXAMPLE_MCP_SERVER_STDIO)
                .serverVersion("1.0.0.0")
                .build());
// DockerClientService is an existing service class to interact with the installed Docker Client
        mediator.registerHandler(McpServiceFactory.create(new DockerClientService(dockerClient))
                .createForNonAnnotatedMethods(false)
                .build());
        mediator.initialize();

DockerClientService:

@McpService(name = "docker_mcp_server",  description = "provides common docker command as mcp tools")
public class DockerClientService {

    DockerClient internalClient;

    @McpTool(name = "docker_start_container",
            description = "start an existing docker container using its containerId! containerId is required and " +
                    "can't be null or empty! if successful, returns true.")
    public boolean startContainerCmd(@NonNull String containerId) {
        internalClient.startContainerCmd(containerId)
                .exec();
        return true;
    }
    // ...
}

Checkout mcp-mediator-implementation-docker for more details.

Proxy MCP Mediator

To create a proxy server:

 // as an example ~/sdk/jdk/jdk-17.0.14+7/Contents/Home/bin/java
String command = args[0];
// e.g., -jar ~/mcp-mediator-example.jar
List<String> remoteServerArgs = List.of(Arrays.copyOfRange(args, 1, args.length));

ProxyMcpMediator mediator = new ProxyMcpMediator(McpMediatorConfigurationBuilder.builder()
       .creatProxy()
       .serializer(new ObjectMapper())
       .tools(true)
       .addRemoteServer(McpMediatorProxyConfiguration.McpMediatorRemoteMcpServerConfiguration.builder()
               .remoteTransportType(McpTransportType.STDIO)
               .remoteServerAddress(command)
               .remoteServerArgs(remoteServerArgs)
               .build())
       .serverName(MY_EXAMPLE_MCP_SERVER_STDIO)
       .serverVersion("1.0.0.0")
       .build());

mediator.initialize();

This mediator creates a Proxy MCP server and connects to all the given remote servers and works as a proxy between the client and the remote servers. The mediator will advertise all the available Tools to the clients during the initialization process. It is also expandable by registering request handlers using ProxyMcpMediator#registerHandler() same as DefaultMcpMediator.

Implemented Query MCP Servers

Query MCP servers are MCP servers that receive a query from the user and search a source for the content related to the input query. All the queries are part of mcp-mediator-implementation-query module and are defined using MCP Mediator Request Handlers. So far, these queries are implemented:

Contributing

Contributions are welcome! Please feel free to submit a Pull Request. Read this first!

License

This project is licensed under the GPL3 License - see the LICENSE file for details.

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