.. index:: single: mcp_server_streamable_http_transport .. _mcp_server_streamable_http_transport/0: .. rst-class:: right **object** ``mcp_server_streamable_http_transport`` ======================================== Implements the Streamable HTTP transport for MCP servers. Uses Logtalk ``http_server::serve_until_shutdown/5`` and a dedicated ``http_handler_protocol`` handler object. Supports specs 2025-06-18, 2025-11-25, and 2026-07-28 selected via the ``spec/1`` option and delegated to the matching ``mcp_server_*_spec`` object. Supports optional OAuth protection and protected-resource metadata publication using the ``oauth/4`` option. Long-lived subscriptions/listen streams emit periodic SSE comment keep-alives (``http_sse_keepalive/1``). Requires a multi-threaded backend for subscriptions/listen. | **Availability:** | ``logtalk_load(mcp_server(loader))`` | **Author:** Paulo Moura | **Version:** 1:0:0 | **Date:** 2026-09-02 | **Compilation flags:** | ``static, context_switching_calls, threaded`` | **Implements:** | ``public`` :ref:`mcp_server_transport_protocol ` | **Imports:** | ``public`` :ref:`mcp_server_application ` | **Uses:** | :ref:`format ` | :ref:`http_oauth ` | :ref:`http_oauth_metadata ` | :ref:`http_server ` | :ref:`json ` | :ref:`json_rpc ` | :ref:`list ` | :ref:`mcp_server_2025_06_18_spec ` | :ref:`mcp_server_2025_11_25_spec ` | :ref:`mcp_server_2026_07_28_spec ` | :ref:`os ` | :ref:`term_io ` | :ref:`type ` | **Remarks:** | (none) | **Inherited public predicates:** |  :ref:`options_protocol/0::check_option/1`  :ref:`options_protocol/0::check_options/1`  :ref:`mcp_server_transport_protocol/0::cleanup/0`  :ref:`options_protocol/0::default_option/1`  :ref:`options_protocol/0::default_options/1`  :ref:`mcp_server_transport_protocol/0::notify/1`  :ref:`options_protocol/0::option/2`  :ref:`options_protocol/0::option/3`  :ref:`mcp_server_transport_protocol/0::spec/1`  :ref:`mcp_server_transport_protocol/0::start/4`  :ref:`mcp_server_application/0::tool_descriptors_to_json/3`  :ref:`options_protocol/0::valid_option/1`  :ref:`options_protocol/0::valid_options/1`   .. contents:: :local: :backlinks: top Public predicates ----------------- .. index:: prepare/2 .. _mcp_server_streamable_http_transport/0::prepare/2: ``prepare/2`` ^^^^^^^^^^^^^ Initializes adapter state for ``Application`` with ``Options`` without opening a listener. Used by unit tests and by embeddings by pairing with ``handle_mcp_request/4`` and ``cleanup/0``. | **Compilation flags:** | ``static`` | **Template:** | ``prepare(Application,Options)`` | **Mode and number of proofs:** | ``prepare(+object_identifier,+list)`` - ``one_or_error`` | **Exceptions:** | ``Options`` is a variable: | ``instantiation_error`` | ``Options`` is neither a variable nor a list: | ``type_error(list,Options)`` | An element ``Option`` of the list ``Options`` is a variable: | ``instantiation_error`` | An element ``Option`` of the list ``Options`` is neither a variable nor a compound term: | ``type_error(compound,Option)`` | An element ``Option`` of the list ``Options`` is a compound term but not a valid option: | ``domain_error(option,Option)`` ------------ .. index:: attach_sse_stream/1 .. _mcp_server_streamable_http_transport/0::attach_sse_stream/1: ``attach_sse_stream/1`` ^^^^^^^^^^^^^^^^^^^^^^^ Registers a live output stream for incremental SSE writes. Headers must already have been written. Each ``emit_progress/5`` call writes and flushes immediately. | **Compilation flags:** | ``static`` | **Template:** | ``attach_sse_stream(Stream)`` | **Mode and number of proofs:** | ``attach_sse_stream(+stream)`` - ``one`` ------------ .. index:: detach_sse_stream/0 .. _mcp_server_streamable_http_transport/0::detach_sse_stream/0: ``detach_sse_stream/0`` ^^^^^^^^^^^^^^^^^^^^^^^ Clears any live SSE output stream registration. | **Compilation flags:** | ``static`` | **Mode and number of proofs:** | ``detach_sse_stream`` - ``one`` ------------ .. index:: sse_headers/1 .. _mcp_server_streamable_http_transport/0::sse_headers/1: ``sse_headers/1`` ^^^^^^^^^^^^^^^^^ HTTP headers for an SSE response body. | **Compilation flags:** | ``static`` | **Template:** | ``sse_headers(Headers)`` | **Mode and number of proofs:** | ``sse_headers(-list)`` - ``one`` ------------ .. index:: current_options/1 .. _mcp_server_streamable_http_transport/0::current_options/1: ``current_options/1`` ^^^^^^^^^^^^^^^^^^^^^ Unified with the options list established by ``prepare/2`` or ``start/4``. | **Compilation flags:** | ``static`` | **Template:** | ``current_options(Options)`` | **Mode and number of proofs:** | ``current_options(-list)`` - ``zero_or_one`` ------------ .. index:: handle_mcp_request/4 .. _mcp_server_streamable_http_transport/0::handle_mcp_request/4: ``handle_mcp_request/4`` ^^^^^^^^^^^^^^^^^^^^^^^^ Handles one MCP HTTP request. ``Method`` is an uppercase HTTP method atom. ``Headers`` is a list of ``Name-Value`` pairs. ``Body`` is the raw request body atom. ``HTTPResponse`` is ``http_response(Status, Headers, BodyAtom)`` or ``http_response(already_sent, Headers, BodyAtom)``. | **Compilation flags:** | ``static`` | **Template:** | ``handle_mcp_request(Method,Headers,Body,HTTPResponse)`` | **Mode and number of proofs:** | ``handle_mcp_request(+atom,+list,+atom,-compound)`` - ``one`` ------------ .. index:: emit_progress/5 .. _mcp_server_streamable_http_transport/0::emit_progress/5: ``emit_progress/5`` ^^^^^^^^^^^^^^^^^^^ Emits a notifications/progress event. In live mode the SSE record is written and flushed immediately on the attached stream. In buffered mode the event is queued until ``finalize_response/4``. | **Compilation flags:** | ``static`` | **Template:** | ``emit_progress(Token,RequestId,ProgressValue,Total,Message)`` | **Mode and number of proofs:** | ``emit_progress(+term,+term,+number,+number,+atom)`` - ``one`` ------------ Protected predicates -------------------- (no local declarations; see entity ancestors if any) Private predicates ------------------ .. index:: running_/0 .. _mcp_server_streamable_http_transport/0::running_/0: ``running_/0`` ^^^^^^^^^^^^^^ True while the adapter has been prepared or is serving requests. | **Compilation flags:** | ``dynamic`` | **Mode and number of proofs:** | ``running_`` - ``zero_or_one`` ------------ .. index:: server_options_/1 .. _mcp_server_streamable_http_transport/0::server_options_/1: ``server_options_/1`` ^^^^^^^^^^^^^^^^^^^^^ Merged server options for the active prepare/start session. | **Compilation flags:** | ``dynamic`` | **Template:** | ``server_options_(Options)`` | **Mode and number of proofs:** | ``server_options_(-list)`` - ``zero_or_one`` ------------ .. index:: shutdown_control_/1 .. _mcp_server_streamable_http_transport/0::shutdown_control_/1: ``shutdown_control_/1`` ^^^^^^^^^^^^^^^^^^^^^^^ Token passed to ``http_server::request_shutdown/1`` when stopping the listener. | **Compilation flags:** | ``dynamic`` | **Template:** | ``shutdown_control_(Control)`` | **Mode and number of proofs:** | ``shutdown_control_(-nonvar)`` - ``zero_or_one`` ------------ .. index:: subscription_/4 .. _mcp_server_streamable_http_transport/0::subscription_/4: ``subscription_/4`` ^^^^^^^^^^^^^^^^^^^ Active subscriptions/listen registration. Synchronization uses ``threaded_wait/1`` and ``threaded_notify/1`` tagged by ``SubscriptionId``. | **Compilation flags:** | ``dynamic`` | **Template:** | ``subscription_(SubscriptionId,RequestId,Filters,Stream)`` | **Mode and number of proofs:** | ``subscription_(-atom,-nonvar,-list,-nonvar)`` - ``zero_or_more`` ------------ .. index:: progress_events_/1 .. _mcp_server_streamable_http_transport/0::progress_events_/1: ``progress_events_/1`` ^^^^^^^^^^^^^^^^^^^^^^ Buffered notifications/progress events when SSE mode is not live. | **Compilation flags:** | ``dynamic`` | **Template:** | ``progress_events_(Events)`` | **Mode and number of proofs:** | ``progress_events_(-list)`` - ``zero_or_one`` ------------ .. index:: progress_token_/1 .. _mcp_server_streamable_http_transport/0::progress_token_/1: ``progress_token_/1`` ^^^^^^^^^^^^^^^^^^^^^ progressToken from the current request, or none. | **Compilation flags:** | ``dynamic`` | **Template:** | ``progress_token_(Token)`` | **Mode and number of proofs:** | ``progress_token_(-nonvar)`` - ``zero_or_one`` ------------ .. index:: sse_output_/1 .. _mcp_server_streamable_http_transport/0::sse_output_/1: ``sse_output_/1`` ^^^^^^^^^^^^^^^^^ Live response stream for incremental SSE writes. | **Compilation flags:** | ``dynamic`` | **Template:** | ``sse_output_(Stream)`` | **Mode and number of proofs:** | ``sse_output_(-stream)`` - ``zero_or_one`` ------------ .. index:: sse_mode_/1 .. _mcp_server_streamable_http_transport/0::sse_mode_/1: ``sse_mode_/1`` ^^^^^^^^^^^^^^^ Current SSE delivery mode: live, buffered, or none. | **Compilation flags:** | ``dynamic`` | **Template:** | ``sse_mode_(Mode)`` | **Mode and number of proofs:** | ``sse_mode_(-atom)`` - ``zero_or_one`` ------------ Operators --------- (none)