io.modelcontextprotocol.client.transport

Class WebRxSseClientTransport

java.lang.Object

io.modelcontextprotocol.client.transport.WebRxSseClientTransport

All Implemented Interfaces:

ClientMcpTransport, McpClientTransport, McpTransport

public class WebRxSseClientTransport
extends Object
implements McpClientTransport

Server-Sent Events (SSE) implementation of the McpTransport that follows the MCP HTTP with SSE transport specification.

This transport establishes a bidirectional communication channel where:

• Inbound messages are received through an SSE connection from the server
• Outbound messages are sent via HTTP POST requests to a server-provided endpoint

The message flow follows these steps:

1. The client establishes an SSE connection to the server's /sse endpoint
2. The server sends an 'endpoint' event containing the URI for sending messages

This implementation uses HttpUtilsBuilder for HTTP communications and supports JSON. and base JDK8 serialization/deserialization of messages.

Author:

Christian Tzolov, noear

See Also:

MCP HTTP with SSE Transport Specification

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	WebRxSseClientTransport.Builder Builder for WebRxSseClientTransport.

Field Summary

Fields

Modifier and Type	Field and Description
protected com.fasterxml.jackson.databind.ObjectMapper	objectMapper JSON object mapper for message serialization/deserialization

Constructor Summary

Constructors

Constructor and Description
WebRxSseClientTransport(org.noear.solon.net.http.HttpUtilsBuilder webBuilder) Creates a new transport instance with default HTTP client and object mapper.
WebRxSseClientTransport(org.noear.solon.net.http.HttpUtilsBuilder webBuilder, com.fasterxml.jackson.databind.ObjectMapper objectMapper) Creates a new transport instance with custom HTTP client builder and object mapper.
WebRxSseClientTransport(org.noear.solon.net.http.HttpUtilsBuilder webBuilder, String sseEndpoint, com.fasterxml.jackson.databind.ObjectMapper objectMapper) Creates a new transport instance with custom HTTP client builder and object mapper.

Method Summary

Modifier and Type	Method and Description
static WebRxSseClientTransport.Builder	builder(org.noear.solon.net.http.HttpUtilsBuilder webBuilder) Creates a new builder for WebRxSseClientTransport.
reactor.core.publisher.Mono<Void>	closeGracefully() Gracefully closes the transport connection.
reactor.core.publisher.Mono<Void>	connect(Function<reactor.core.publisher.Mono<McpSchema.JSONRPCMessage>,reactor.core.publisher.Mono<McpSchema.JSONRPCMessage>> handler) Establishes the SSE connection with the server and sets up message handling.
reactor.core.publisher.Mono<Void>	sendMessage(McpSchema.JSONRPCMessage message) Sends a JSON-RPC message to the server.
<T> T	unmarshalFrom(Object data, com.fasterxml.jackson.core.type.TypeReference<T> typeRef) Unmarshals data to the specified type using the configured object mapper.

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.McpTransport

close

Field Detail

objectMapper

protected com.fasterxml.jackson.databind.ObjectMapper objectMapper

JSON object mapper for message serialization/deserialization

Constructor Detail

WebRxSseClientTransport

public WebRxSseClientTransport(org.noear.solon.net.http.HttpUtilsBuilder webBuilder)

Creates a new transport instance with default HTTP client and object mapper.

Parameters:

webBuilder - the HttpUtilsBuilder to use for creating the HttpUtils instance

WebRxSseClientTransport

public WebRxSseClientTransport(org.noear.solon.net.http.HttpUtilsBuilder webBuilder,
                               com.fasterxml.jackson.databind.ObjectMapper objectMapper)

Creates a new transport instance with custom HTTP client builder and object mapper.

Parameters:

webBuilder - the HttpUtilsBuilder to use for creating the HttpUtils instance

objectMapper - the object mapper for JSON serialization/deserialization

Throws:

IllegalArgumentException - if objectMapper or clientBuilder is null

WebRxSseClientTransport

public WebRxSseClientTransport(org.noear.solon.net.http.HttpUtilsBuilder webBuilder,
                               String sseEndpoint,
                               com.fasterxml.jackson.databind.ObjectMapper objectMapper)

Creates a new transport instance with custom HTTP client builder and object mapper.

Parameters:

webBuilder - the HttpUtilsBuilder to use for creating the HttpUtils instance

sseEndpoint - the SSE endpoint path

objectMapper - the object mapper for JSON serialization/deserialization

Throws:

IllegalArgumentException - if objectMapper or clientBuilder is null

Method Detail

builder

public static WebRxSseClientTransport.Builder builder(org.noear.solon.net.http.HttpUtilsBuilder webBuilder)

Creates a new builder for WebRxSseClientTransport.

Parameters:

webBuilder - the HttpUtilsBuilder to use for creating the HttpUtils instance

Returns:

a new builder instance

connect

public reactor.core.publisher.Mono<Void> connect(Function<reactor.core.publisher.Mono<McpSchema.JSONRPCMessage>,reactor.core.publisher.Mono<McpSchema.JSONRPCMessage>> handler)

Establishes the SSE connection with the server and sets up message handling.

This method:

• Initiates the SSE connection
• Handles endpoint discovery events
• Processes incoming JSON-RPC messages

Specified by:

connect in interface McpClientTransport

Specified by:

connect in interface McpTransport

Parameters:

handler - the function to process received JSON-RPC messages

Returns:

a Mono that completes when the connection is established

sendMessage

public reactor.core.publisher.Mono<Void> sendMessage(McpSchema.JSONRPCMessage message)

Sends a JSON-RPC message to the server.

This method waits for the message endpoint to be discovered before sending the message. The message is serialized to JSON and sent as an HTTP POST request.

Specified by:

sendMessage in interface McpTransport

Parameters:

message - the JSON-RPC message to send

Returns:

a Mono that completes when the message is sent

Throws:

McpError - if the message endpoint is not available or the wait times out

closeGracefully

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

Gracefully closes the transport connection.

Sets the closing flag and cancels any pending connection future. This prevents new messages from being sent and allows ongoing operations to complete.

Specified by:

closeGracefully in interface McpTransport

Returns:

a Mono that completes when the closing process is initiated

unmarshalFrom

public <T> T unmarshalFrom(Object data,
                           com.fasterxml.jackson.core.type.TypeReference<T> typeRef)

Unmarshals data to the specified type using the configured object mapper.

Specified by:

unmarshalFrom in interface McpTransport

Type Parameters:

T - the target type

Parameters:

data - the data to unmarshal

typeRef - the type reference for the target type

Returns:

the unmarshalled object