Class StreamableHttpMcpTransport

java.lang.Object
dev.langchain4j.mcp.client.transport.http.StreamableHttpMcpTransport
All Implemented Interfaces:
McpTransport, Closeable, AutoCloseable
public class StreamableHttpMcpTransport extends Object implements McpTransport

  • Constructor Details

  • Method Details

    • start

      public void start(McpOperationHandler operationHandler)
      Description copied from interface: McpTransport
      Creates a connection to the MCP server (runs the server as a subprocess if needed). This does NOT yet send the "initialize" message to negotiate capabilities.
      Specified by:
      start in interface McpTransport

    • sendInitializeRequest

      public CompletableFuture<String> sendInitializeRequest(McpInitializeRequest operation)
      Description copied from interface: McpTransport
      Sends the MCP InitializeRequest and returns the server's response as unparsed JSON text, so that a transport does not need a JSON library. This has to be called AFTER the "start" method; when it returns successfully, the transport is ready to be used. Only used with the legacy MCP protocol (versions up to 2025-11-25); the modern protocol uses server/discover.
      Specified by:
      sendInitializeRequest in interface McpTransport

    • sendRequest

      public CompletableFuture<String> sendRequest(McpCallContext context)
      Description copied from interface: McpTransport
      Sends a JSON-RPC request and returns the server's response as unparsed JSON text. The context carries the message and its per-call headers and _meta, which the transport applies.
      Specified by:
      sendRequest in interface McpTransport

    • sendMessage

      public void sendMessage(McpCallContext context)
      Description copied from interface: McpTransport
      Sends a message that does not expect a reply - in MCP terms a notification, or a response to a server-initiated request. The context carries the message and its per-call headers and _meta, which the transport applies.
      Specified by:
      sendMessage in interface McpTransport

    • checkHealth

      public void checkHealth()
      Description copied from interface: McpTransport
      Performs transport-specific health checks, if applicable. This is called by `McpClient.checkHealth()` as the first check before performing a check by sending a 'ping' over the MCP protocol. The purpose is that the transport may have some specific and faster ways to detect that it is broken, like for example, the STDIO transport can fail the check if it detects that the server subprocess isn't alive anymore.
      Specified by:
      checkHealth in interface McpTransport

    • onFailure

      public void onFailure(Runnable actionOnFailure)
      Specified by:
      onFailure in interface McpTransport

    • getMcpSessionId

      public String getMcpSessionId()
      Returns the MCP session ID assigned by the server, or null if no session has been established yet (or the server does not use sessions). The session ID is captured from the Mcp-Session-Id response header during initialization and reused on subsequent requests via the same header. This only applies to the legacy protocol (before 2026-07-28).

    • setMcpSessionId

      public void setMcpSessionId(String mcpSessionId)
      Sets the MCP session ID to be sent on subsequent requests via the Mcp-Session-Id header. This is intended for scenarios where a session obtained elsewhere (for example, in another process or pod) needs to be resumed by this transport, allowing stateless deployments without sticky sessions. This only applies to the legacy protocol (before 2026-07-28).

    • setModernProtocol

      public void setModernProtocol(boolean modernProtocol)
      Enables or disables modern protocol mode. When enabled, the transport sends modern protocol headers (MCP-Protocol-Version, Mcp-Method, Mcp-Name) and skips legacy session management (Mcp-Session-Id header and 404-triggered reinitialization).
      Specified by:
      setModernProtocol in interface McpTransport

    • setProtocolVersion

      public void setProtocolVersion(String protocolVersion)
      Sets the protocol version to be sent in the MCP-Protocol-Version header when modern protocol mode is enabled.
      Specified by:
      setProtocolVersion in interface McpTransport

    • requiresCancellationNotification

      public boolean requiresCancellationNotification()
      Description copied from interface: McpTransport
      Returns whether this transport requires an explicit notifications/cancelled message to cancel an in-progress request. Transports that use per-request SSE streams (like Streamable HTTP) cancel by closing the stream and should return false. Transports that share a single channel (like stdio) must return true so the server knows which request to cancel.

      Note: when using the legacy protocol (2025-11-25), the client always sends notifications/cancelled regardless of this value, because the legacy spec states that disconnection should not be interpreted as cancellation.

      Defaults to true, which is the safe answer for a transport that shares a single channel; per-request-stream transports override it.

      Specified by:
      requiresCancellationNotification in interface McpTransport

    • close

      public void close() throws IOException
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Throws:
      IOException

    • builder

      public static StreamableHttpMcpTransport.Builder builder()