Package io.vertx.ext.mcp.transport

Class VertxMcpSseServerTransportProvider

java.lang.Object

io.vertx.ext.mcp.transport.VertxMcpSseServerTransportProvider

All Implemented Interfaces:

io.modelcontextprotocol.spec.McpServerTransportProvider, io.modelcontextprotocol.spec.McpServerTransportProviderBase, VertxMcpTransport

public class VertxMcpSseServerTransportProvider
extends Object
implements io.modelcontextprotocol.spec.McpServerTransportProvider, VertxMcpTransport

Server-side implementation of the MCP (Model Context Protocol) HTTP transport using Vert.x and Server-Sent Events (SSE). This implementation provides a bidirectional communication channel between MCP clients and servers using HTTP POST for client-to-server messages and SSE for server-to-client messages.

Key features:

• Implements the McpServerTransportProvider interface that allows managing McpServerSession instances and enabling their communication with the McpServerTransport abstraction.
• Uses Vert.x for non-blocking request handling and SSE support
• Maintains client sessions for reliable message delivery
• Supports graceful shutdown with session cleanup
• Thread-safe message broadcasting to multiple clients

The transport sets up two main endpoints:

• SSE endpoint (/sse) - For establishing SSE connections with clients
• Message endpoint (configurable) - For receiving JSON-RPC messages from clients

This implementation is thread-safe and can handle multiple concurrent client connections. It uses ConcurrentHashMap for session management and Vert.x's non-blocking APIs for message processing and delivery. Created By Navíd Mitchell 🤪on 8/10/25

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	VertxMcpSseServerTransportProvider.VertxMcpSseServerTransportProviderBuilder

Field Summary

Fields

Modifier and Type	Field	Description
static final Duration	DEFAULT_KEEP_ALIVE_INTERVAL	Default keep alive interval as specified by the MCP transport specification.
static final String	DEFAULT_MESSAGE_ENDPOINT	Default message endpoint path as specified by the MCP transport specification.
static final String	DEFAULT_SSE_ENDPOINT	Default SSE endpoint path as specified by the MCP transport specification.
static final String	ENDPOINT_EVENT_TYPE	Event type for sending the message endpoint URI to clients.
static final String	MESSAGE_EVENT_TYPE	Event type for JSON-RPC messages sent through the SSE connection.

Constructor Summary

Constructors

Constructor	Description
VertxMcpSseServerTransportProvider(String baseUrl, String messageEndpoint, String sseEndpoint, Duration keepAliveInterval, com.fasterxml.jackson.databind.ObjectMapper objectMapper, io.vertx.core.Vertx vertx)

Method Summary

Modifier and Type	Method	Description
static VertxMcpSseServerTransportProvider.VertxMcpSseServerTransportProviderBuilder	builder()
reactor.core.publisher.Mono<Void>	closeGracefully()	Close the Vert.x MCP transport gracefully.
io.vertx.ext.web.Router	getRouter()	Returns the Router that can be mounted into a Vert.x application.
reactor.core.publisher.Mono<Void>	notifyClients(String method, Object params)
List<String>	protocolVersions()
void	setSessionFactory(io.modelcontextprotocol.spec.McpServerSession.Factory sessionFactory)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface io.modelcontextprotocol.spec.McpServerTransportProviderBase

close

Field Details

MESSAGE_EVENT_TYPE

public static final String MESSAGE_EVENT_TYPE

Event type for JSON-RPC messages sent through the SSE connection.

See Also:

• Constant Field Values

ENDPOINT_EVENT_TYPE

public static final String ENDPOINT_EVENT_TYPE

Event type for sending the message endpoint URI to clients.

See Also:

• Constant Field Values

DEFAULT_SSE_ENDPOINT

public static final String DEFAULT_SSE_ENDPOINT

Default SSE endpoint path as specified by the MCP transport specification.

See Also:

• Constant Field Values

DEFAULT_MESSAGE_ENDPOINT

public static final String DEFAULT_MESSAGE_ENDPOINT

Default message endpoint path as specified by the MCP transport specification.

See Also:

• Constant Field Values

DEFAULT_KEEP_ALIVE_INTERVAL

public static final Duration DEFAULT_KEEP_ALIVE_INTERVAL

Default keep alive interval as specified by the MCP transport specification.

Constructor Details

VertxMcpSseServerTransportProvider

public VertxMcpSseServerTransportProvider(String baseUrl,
 String messageEndpoint,
 String sseEndpoint,
 Duration keepAliveInterval,
 com.fasterxml.jackson.databind.ObjectMapper objectMapper,
 io.vertx.core.Vertx vertx)

Method Details

getRouter

public io.vertx.ext.web.Router getRouter()

Returns the Router that can be mounted into a Vert.x application. This router contains all the MCP transport endpoints.

Specified by:

getRouter in interface VertxMcpTransport

Returns:

The configured Router for handling MCP HTTP requests

protocolVersions

public List<String> protocolVersions()

Specified by:

protocolVersions in interface io.modelcontextprotocol.spec.McpServerTransportProviderBase

setSessionFactory

public void setSessionFactory(io.modelcontextprotocol.spec.McpServerSession.Factory sessionFactory)

Specified by:

setSessionFactory in interface io.modelcontextprotocol.spec.McpServerTransportProvider

notifyClients

public reactor.core.publisher.Mono<Void> notifyClients(String method,
 Object params)

Specified by:

notifyClients in interface io.modelcontextprotocol.spec.McpServerTransportProviderBase

closeGracefully

public reactor.core.publisher.Mono<Void> closeGracefully()

Description copied from interface: VertxMcpTransport

Close the Vert.x MCP transport gracefully.

Specified by:

closeGracefully in interface io.modelcontextprotocol.spec.McpServerTransportProviderBase

Specified by:

closeGracefully in interface VertxMcpTransport

Returns:

A Mono that completes when the transport is closed.

builder

public static VertxMcpSseServerTransportProvider.VertxMcpSseServerTransportProviderBuilder builder()