kotlin-sdk-client/io.modelcontextprotocol.kotlin.sdk.client/StreamableHttpClientTransport

StreamableHttpClientTransport

class StreamableHttpClientTransport(client: HttpClient, url: String, reconnectionOptions: ReconnectionOptions = ReconnectionOptions(), maxInlineSseEventSize: Int = DEFAULT_MAX_INLINE_SSE_EVENT_SIZE, requestBuilder: HttpRequestBuilder.() -> Unit = {}) : AbstractClientTransport(source)

Client transport implementing the MCP Streamable HTTP transport specification.

Sends messages via HTTP POST and receives messages via HTTP GET with Server-Sent Events. Supports automatic SSE reconnection with exponential backoff, stream resumption via the Last-Event-ID header, and explicit session termination.

Parameters

client

Ktor HTTP client used for all requests

url

MCP endpoint URL

reconnectionOptions

reconnection backoff and retry-limit settings for the SSE stream

maxInlineSseEventSize

maximum size, in characters, of a single inline SSE event parsed from a POST response; a server that exceeds it (including by never terminating an event) fails the send with io.modelcontextprotocol.kotlin.sdk.shared.TooLongFrameException. Defaults to 16 MiB.

requestBuilder

builder applied to every outgoing HTTP request, e.g. for adding auth headers

Constructors

StreamableHttpClientTransport

constructor(client: HttpClient, url: String, reconnectionOptions: ReconnectionOptions = ReconnectionOptions(), maxInlineSseEventSize: Int = DEFAULT_MAX_INLINE_SSE_EVENT_SIZE, requestBuilder: HttpRequestBuilder.() -> Unit = {})

constructor(client: HttpClient, url: String, reconnectionTime: Duration?, requestBuilder: HttpRequestBuilder.() -> Unit = {})

Properties

protocolVersion

var protocolVersion: String?

MCP protocol version negotiated with the server, or null before connection.

sessionId

var sessionId: String?

Session identifier assigned by the server after initialization, or null before connection.

Functions

open suspend override fun close()

onClose

open override fun onClose(block: () -> Unit)

onError

open override fun onError(block: (Throwable) -> Unit)

onMessage

open override fun onMessage(block: suspend (JSONRPCMessage) -> Unit)

send

suspend fun send(message: JSONRPCMessage, resumptionToken: String?, onResumptionToken: (String) -> Unit? = null)

Sends one or more messages with optional resumption support. This is the main send method that matches the TypeScript implementation.

open suspend override fun send(message: JSONRPCMessage, options: TransportSendOptions?)

start

open suspend override fun start()

terminateSession

suspend fun terminateSession()

Terminates the current session by sending a DELETE request to the server.