Python-spdylay - Spdylay Python Extension Module ================================================ .. py:module:: spdylay Python-spdylay is the Python extension module of Spdylay SPDY C library. Build ----- To generate C source code from ``spdylay.pyx``, run ``cython``:: $ cython spdylay.pyx To build extension, run ``setup.py``:: $ python setup.py build_ext Session Objects --------------- .. py:class:: Session(side, version, config=None, send_cb=None, recv_cb=None, on_ctrl_recv_cb=None, on_invalid_ctrl_recv_cb=None, on_data_chunk_recv_cb=None, on_data_recv_cb=None, before_ctrl_send_cb=None, on_ctrl_send_cb=None, on_ctrl_not_send_cb=None, on_data_send_cb=None, on_stream_close_cb=None, on_request_recv_cb=None, on_ctrl_recv_parse_error_cb=None, on_unknown_ctrl_recv_cb=None, user_data=None) This is the class to hold the resources needed for a SPDY session. Sending and receiving SPDY frames are done using the methods of this class. The *side* specifies server or client. Use one of the following: .. py:data:: CLIENT Indicates client. .. py:data:: SERVER Indicates server. The *version* specifies SPDY protocol version. Use of the following: .. py:data:: PROTO_SPDY2 Indicates SPDY/2. .. py:data:: PROTO_SPDY3 Indicates SPDY/3. The *user_data* specifies opaque object tied to this object. It can be accessed through :py:attr:`user_data` attribute. The *recv_cb* specifies callback function (callable) invoked when the object wants to receive data from the remote peer. The signature of this callback is: .. py:function:: recv_cb(session, length) The *session* is the :py:class:`Session` object invoking the callback. The implementation of this function must read at most *length* bytes of bytestring and return it. If it cannot read any single byte without blocking, it must return empty bytestring or ``None``. If it gets EOF before it reads any single byte, it must raise :py:class:`EOFError`. For other errors, it must raise :py:class:`CallbackFailureError`. The *send_cb* specifies callback function (callable) invoked when session wants to send data to the remote peer. The signature of this callback is: .. py:function:: send_cb(session, data) The *session* is the :py:class:`Session` object invoking the callback. The *data* is the bytestring to send. The implementation of this function will send all or part of *data*. It must return the number of bytes sent if it succeeds. If it cannot send any single byte without blocking, it must return 0 or ``None``. For other errors, it must return :py:class:`CallbackFailureError`. The *on_ctrl_recv_cb* specifies callback function (callable) invoked when a control frame is received. .. py:function:: on_ctrl_recv_cb(session, frame) The *session* is the :py:class:`Session` object invoking the callback. The *frame* is the received control frame. ``frame.frame_type`` tells the type of frame. See `Frame Types`_ for the details. Once the frame type is identified, access attribute of the *frame* to get information. The *on_invalid_ctrl_recv_cb* specifies callback function (callable) invoked when an invalid control frame is received. .. py:function:: on_invalid_ctrl_recv_cb(session, frame, status_code) The *session* is the :py:class:`Session` object invoking the callback. The *frame* is the received control frame. ``frame.frame_type`` tells the type of frame. See `Frame Types`_ for the details. Once the frame type is identified, access attribute of the *frame* to get information. The *status_code* is one of the `Stream Status Codes`_ and indicates the error. When this callback function is invoked, either RST_STREAM or GOAWAY will be sent. The *on_data_chunk_recv_cb* specifies callback function (callable) invoked when a chunk of data in DATA frame is received. .. py:function:: on_data_chunk_recv_cb(session, flags, stream_id, data) The *session* is the :py:class:`Session` object invoking the callback. The *stream_id* is the stream ID this DATA frame belongs to. The *flags* is the flags of DATA frame which this data chunk is contained. ``(flags & DATA_FLAG_FIN) != 0`` does not necessarily mean this chunk of data is the last one in the stream. You should use :py:func:`on_data_recv_cb` to know all data frames are received. The *data* is the bytestring of received data. The *on_data_recv_cb* specifies callback function (callable) invoked when DATA frame is received. .. py:function:: on_data_recv_cb(session, flags, stream_id, length) The actual data it contains are received by :py:func:`on_data_chunk_recv_cb()`. The *before_ctrl_send_cb* specifies callback function (callable) invoked before the control frame is sent. .. py:function:: before_ctrl_send_cb(session, frame) The *session* is the :py:class:`Session` object invoking the callback. The *frame* is the control frame to be sent. ``frame.frame_type`` tells the type of frame. See `Frame Types`_ for the details. Once the frame type is identified, access attribute of the *frame* to get information. The *on_ctrl_send_cb* specifies callback function (callable) invoked after the control frame is sent. .. py:function:: on_ctrl_send_cb(session, frame) The *session* is the :py:class:`Session` object invoking the callback. The *frame* is the control frame to be sent. ``frame.frame_type`` tells the type of frame. See `Frame Types`_ for the details. Once the frame type is identified, access attribute of the *frame* to get information. The *on_ctrl_not_send_cb* specifies callback function (callable) after the control frame is not sent because of the error. .. py:function:: on_ctrl_not_send_cb(session, frame, error_code) The *session* is the :py:class:`Session` object invoking the callback. The *frame* is the received control frame. ``frame.frame_type`` tells the type of frame. See `Frame Types`_ for the details. Once the frame type is identified, access attribute of the *frame* to get information. The *error_code* is one of the `Error Codes`_ and indicates the error. The *on_data_send_cb* specifies callback function (callable) invoked after DATA frame is sent. .. py:function:: on_data_send_cb(session, flags, stream_id, length) The *on_stream_close_cb* specifies callback function (callable) invoked when the stream is closed. .. py:function:: on_stream_close_cb(session, stream_id, status_code) The *session* is the :py:class:`Session` object invoking the callback. The *stream_id* indicates the stream ID. The reason of closure is indicated by the *status_code*. See `Stream Status Codes`_ for the details. The stream_user_data, which was specified in :py:meth:`submit_request()` or :py:meth:`submit_syn_stream()`, is still available in this function. The *on_request_recv_cb* specifies callback function (callable) invoked when the request from the remote peer is received. In other words, the frame with FIN flag set is received. In HTTP, this means HTTP request, including request body, is fully received. .. py:function:: on_request_recv_cb(session, stream_id) The *session* is the :py:class:`Session` object invoking the callback. The *stream_id* indicates the stream ID. The *on_ctrl_recv_parse_error_cb* specifies callback function (callable) invoked when the received control frame octets could not be parsed correctly. .. py:function:: on_ctrl_recv_parse_error_cb(session, type, head, payload, error_code) The *type* indicates the type of received control frame. The *head* is the bytestring of control frame header. The *payload* is the bytestring of data portion of the received frame. The *error_code* is one of the error code defined in `Error Codes`_ and indicates the error. The *on_unknown_ctrl_recv_cb* specifies callback function (callable) invoked when the received control frame type is unknown. .. py:function:: on_unknown_ctrl_recv_cb(session, head, payload) The *head* is the bytestring of control frame header. The *payload* is the bytestring of data portion of the received frame. The :py:class:`InvalidArgumentError` will be raised if the given argument is invalid. The :py:class:`UnsupportedVersionError` will be raised if the *version* is not supported. The :py:class:`ZlibError` will be raised if initialization of zlib failed. .. py:attribute:: Session.user_data The object passed in the constructor as *user_data* argument. This attribute is read-only. .. py:method:: Session.send() Sends pending frames to the remote peer. This method retrieves the highest prioritized frame from the outbound queue and sends it to the remote peer. It does this as many as possible until the user callback :py:func:`send_cb` returns 0 or ``None`` or the outbound queue becomes empty. This method calls several callback functions which are passed when initializing the session. See :func:`spdylay_session_send` about the callback functions invoked from this method. The :py:class:`CallbackFailureError` will be raised if the callback function failed. .. py:method:: Session.recv(data=None) Receives frames from the remote peer. This method receives as many frames as possible until the user callback :py:func:`recv_cb` returns empty bytestring or ``None``. This function calls several callback functions which are passed when initializing the session. See :func:`spdylay_session_recv` about the callback functions invoked from this method. If data is ``None``, this method will invoke :py:func:`recv_cb` callback function to receive incoming data. If data is not ``None``, it must be a bytestring and this method uses it as the incoming data and does not call :py:func:`recv_cb` callback function. The :py:class:`EOFError` will be raised if the remote peer did shutdown on the connection. The :py:class:`CallbackFailureError` will be raised if the callback function failed. .. py:method:: Session.resume_data(stream_id) Puts back previously deferred DATA frame in the stream *stream_id* to the outbound queue. The :py:class:`InvalidArgumentError` will be raised if the stream does not exist or no deferred data exist. .. py:method:: Session.want_read() Returns ``True`` if session wants to receive data from the remote peer. If both :py:meth:`want_read()` and :py:meth:`want_write()` return ``False``, the application should drop the connection. .. py:method:: Session.want_write() Returns ``True`` if session wants to send data to the remote peer. If both :py:meth:`want_read()` and :py:meth:`want_write()` return ``False``, the application should drop the connection. .. py:method:: Session.get_stream_user_data(stream_id) Returns stream_user_data for the stream *stream_id*. The stream_user_data is provided by :py:meth:`submit_request()` or :py:meth:`submit_syn_stream()`. If the stream is initiated by the remote endpoint, stream_user_data is always ``None``. If the stream is initiated by the local endpoint and ``None`` is given in :py:meth:`submit_request()` or :py:meth:`submit_syn_stream()`, then this function returns ``None``. If the stream does not exist, this function returns ``None``. .. py:method:: Session.get_outbound_queue_size() Returns the number of frames in the outbound queue. This does not include the deferred DATA frames. .. py:method:: Session.get_pri_lowest() Returns lowest priority value for the session. .. py:method:: Session.fail_session(status_code) Submits GOAWAY frame. The status code *status_code* is ignored if the protocol version is :py:const:`PROTO_SPDY2`. This method should be called when the connection should be terminated after sending GOAWAY. If the remaining streams should be processed after GOAWAY, use :py:meth:`submit_goaway()` instead. .. py:method:: Session.submit_request(pri, nv, data_prd=None, stream_user_data=None) Submits SYN_STREAM frame and optionally one or more DATA frames. The *pri* is priority of this request. ``0`` is the highest priority value. Use :py:meth:`get_pri_lowest()` to know the lowest priority value for this session. The *nv* is a list containing the name/value pairs. The each element is a tuple of 2 bytestrings: name and value (e.g., ``(b'host', b'localhost')``). The *nv* must include following name/value pairs: ``:method`` HTTP method (e.g., ``GET``, ``POST``, ``HEAD``, etc) ``:scheme`` URI scheme (e.g., ``https``) ``:path`` Absolute path and parameters of this request (e.g., ``/foo``, ``/foo;bar;haz?h=j&y=123``) ``:version`` HTTP version (e.g., ``HTTP/1.1``) ``:host`` The hostport portion of the URI for this request (e.g., ``example.org:443``). This is the same as the HTTP “Host” header field. If the session is initialized with the version :py:const:`PROTO_SPDY2`, the above names are translated to ``method``, ``scheme``, ``url``, ``version`` and ``host`` respectively. The names in *nv* will be lower-cased when they are sent. If *data_prd* is not ``None``, it provides data which will be sent in subsequent DATA frames. In this case, a method that allows request message bodies (http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html#sec9) must be specified with ``:method`` key in nv (e.g. ``POST``). The type of *data_prd* is expected to be :py:class:`DataProvider`. If *data_prd* is ``None``, SYN_STREAM have FLAG_FIN set. .. note:: This method does not increase reference count of *data_prd*, so the application must hold the reference to it until the stream is closed. The *stream_user_data* is data associated to the stream opened by this request and can be an arbitrary object, which can be retrieved later by :py:meth:`get_stream_user_data()`. Since the library reorders the frames and tries to send the highest prioritized one first and the SPDY specification requires the stream ID must be strictly increasing, the stream ID of this request cannot be known until it is about to sent. To know the stream ID of the request, the application can use :py:func:`before_ctrl_send_cb`. This callback is called just before the frame is sent. For SYN_STREAM frame, the argument frame has the stream ID assigned. Also since the stream is already opened, :py:meth:`get_stream_user_data()` can be used to get stream_user_data to identify which SYN_STREAM we are processing. The :py:class:`InvalidArgumentError` will be raised if the *pri* is invalid; or the *nv* includes empty name or ``None`` value. .. py:method:: Session.submit_response(stream_id, nv, data_prd=None) Submits SYN_REPLY frame and optionally one or more DATA frames against the stream *stream_id*. The *nv* is a list containing the name/value pairs. The each element is a tuple of 2 bytestrings: name and value (e.g., ``(b'host', b'localhost')``). The *nv* must include following name/value pairs: ``:status`` HTTP status code (e.g., ``200`` or ``200 OK``) ``:version`` HTTP response version (e.g., ``HTTP/1.1``) If the session is initialized with the version :py:const:`PROTO_SPDY2`, the above names are translated to ``status`` and ``version`` respectively. The names in *nv* will be lower-cased when they are sent. If *data_prd* is not ``None``, it provides data which will be sent in subsequent DATA frames. The type of *data_prd* is expected to be :py:class:`DataProvider`. If *data_prd* is ``None``, SYN_REPLY have FLAG_FIN set. .. note:: This method does not increase reference count of *data_prd*, so the application must hold the reference to it until the stream is closed. The :py:class:`InvalidArgumentError` will be raised if the *nv* includes empty name or ``None`` value. .. py:method:: Session.submit_syn_stream(flags, assoc_stream_id, pri, nv, stream_user_data) Submits SYN_STREAM frame. The *flags* is bitwise OR of the following values: * :py:const:`CTRL_FLAG_FIN` * :py:const:`CTRL_FLAG_UNIDIRECTIONAL` If *flags* includes :py:const:`CTRL_FLAG_FIN`, this frame has FLAG_FIN flag set. The *assoc_stream_id* is used for server-push. Specify 0 if this stream is not server-push. If session is initialized for client use, *assoc_stream_id* is ignored. The *pri* is priority of this request. ``0`` is the highest priority value. Use :py:meth:`get_pri_lowest()` to know the lowest priority value for this session. The *nv* is a list containing the name/value pairs. The each element is a tuple of 2 bytestrings: name and value (e.g., ``(b'host', b'localhost')``). The names in *nv* will be lower-cased when they are sent. The *stream_user_data* is data associated to the stream opened by this request and can be an arbitrary object, which can be retrieved later by :py:meth:`get_stream_user_data()`. This function is low-level in a sense that the application code can specify flags and the Associated-To-Stream-ID directly. For usual HTTP request, :py:meth:`submit_request()` is useful. The :py:class:`InvalidArgumentError` will be raised if the *pri* is invalid; or the *assoc_stream_id* is invalid; or the *nv* includes empty name or ``None`` value. .. py:method:: Session.submit_syn_reply(flags, stream_id, nv) Submits SYN_REPLY frame. The *flags* is bitwise OR of the following values: * :py:const:`CTRL_FLAG_FIN` If *flags* includes :py:const:`CTRL_FLAG_FIN`, this frame has FLAG_FIN flag set. The stream which this frame belongs to is given in the *stream_id*. The *nv* is the name/value pairs in this frame. The *nv* is a list containing the name/value pairs. The each element is a tuple of 2 bytestrings: name and value (e.g., ``(b'host', b'localhost')``). The names in *nv* will be lower-cased when they are sent. The :py:class:`InvalidArgumentError` will be raised if the *nv* includes empty name or ``None`` value. .. py:method:: Session.submit_headers(flags, stream_id, nv) Submits HEADERS frame. The *flags* is bitwise OR of the following values: * :py:const:`CTRL_FLAG_FIN` If *flags* includes :py:const:`CTRL_FLAG_FIN`, this frame has FLAG_FIN flag set. The stream which this frame belongs to is given in the *stream_id*. The *nv* is the name/value pairs in this frame. The *nv* is a list containing the name/value pairs. The each element is a tuple of 2 bytestrings: name and value (e.g., ``(b'host', b'localhost')``). The names in *nv* will be lower-cased when they are sent. The :py:class:`InvalidArgumentError` will be raised if the *nv* includes empty name or ``None`` value. .. py:method:: Session.submit_data(stream_id, flags, data_prd) Submits one or more DATA frames to the stream *stream_id*. The data to be sent are provided by *data_prd*. The type of *data_prd* is expected to be :py:class:`DataProvider`. If *flags* contains :py:const:`DATA_FLAG_FIN`, the last DATA frame has FLAG_FIN set. .. note:: This method does not increase reference count of *data_prd*, so the application must hold the reference to it until the stream is closed. .. py:method:: Session.submit_rst_stream(stream_id, status_code) Submits RST_STREAM frame to cancel/reject the stream *stream_id* with the status code *status_code*. See `Stream Status Codes`_ for available status codes. .. py:method:: Session.submit_ping() Submits PING frame. .. py:method:: Session.submit_goaway(status_code) Submits GOAWAY frame. The status code *status_code* is ignored if the protocol version is :py:const:`PROTO_SPDY2`. See `GOAWAY Status Codes`_ for available status codes. .. py:method:: Session.submit_settings(flags, iv) Stores local settings and submits SETTINGS frame. The *flags* is bitwise OR of the values described in `SETTINGS Frame Flags`_. The *iv* is a list of tuple ``(settings_id, flag, value)``. For settings_id, see `SETTINGS IDs`_. For flag, see `SETTINGS ID Flags`_. The :py:class:`InvalidArgumentError` will be raised if the *iv* contains duplicate settings ID or invalid value. .. py:method:: Session.submit_window_update(stream_id, delta_window_size) Submits WINDOW_UPDATE frame. The effective range of the *delta_window_size* is ``[1, (1 << 31)-1]``, inclusive. But the application must be responsible to keep the resulting window ``size <= (1 << 31)-1``. The :py:class:`InvalidArgumentError` will be raised if the *delta_window_size* is 0 or negative. The :py:class:`StreamClosedError` will be raised if the stream is already closed or does not exist. Data Provider Objects --------------------- .. py:class:: DataProvider(source, read_cb) This class represents the data source and the way to read a chunk of data from it. The *source* is expected to be the data source to read, but the application can freely pass any object including ``None``. The *read_cb* is the callback function invoked when the library needs to read data. The data read will be sent as DATA frame. .. py:function:: read_cb(session, stream_id, length, read_ctrl, source) The *session* is the :py:class:`Session` object. The *stream_id* is the stream to send data. The *source* is the object passed as a *source* in DataProvider constructor. The implementation of this callback must read at most *length* bytes of data and return it as bytestring. When all data is read, assign :py:const:`READ_EOF` to ``read_ctrl.flags``. If the application wants to postpone DATA frames, (e.g., asynchronous I/O, or reading data blocks for long time), it is achieved by returning :py:const:`ERR_DEFERRED` without reading any data in this invocation. The library removes DATA frame from the outgoing queue temporarily. To move back deferred DATA frame to outgoing queue, call :py:meth:`Session.resume_data()`. In case of error, there are 2 choices. Raising :py:class:`TemporalCallbackFailureError` will close the stream by issuing RST_STREAM with :py:const:`INTERNAL_ERROR`. Raising :py:class:`CallbackFailureError` will signal the entire session failure. .. py:attribute:: DataProvider.source .. py:attribute:: DataProvider.read_cb Control Frame Objects --------------------- .. py:class:: CtrlFrame The base class of SPDY control frames. .. py:attribute:: version Version .. py:attribute:: frame_type Frame type. See `Frame Types`_. .. py:attribute:: flags Flags. See `Control Frame Flags`_. .. py:attribute:: length Frame payload length The following frame classes inherit :py:class:`CtrlFrame` class. .. py:class:: SynStreamFrame .. py:attribute:: stream_id Stream ID .. py:attribute:: assoc_stream_id Associated-To-Stream-ID .. py:attribute:: pri Priority .. py:attribute:: slot Credential slot .. py:attribute:: nv List of name/value pair. .. py:class:: SynReplyFrame .. py:attribute:: stream_id Stream ID .. py:attribute:: nv List of name/value pair. .. py:class:: HeadersFrame .. py:attribute:: stream_id Stream ID .. py:attribute:: nv List of name/value pair. .. py:class:: RstStreamFrame .. py:attribute:: stream_id Stream ID .. py:attribute:: status_code Status code .. py:class:: SettingsFrame .. py:attribute:: iv List of tuple ``(settings_id, flags, value)`` .. py:class:: PingFrame .. py:attribute:: unique_id Unique ID .. py:class:: GoawayFrame .. py:attribute:: last_good_stream_id Last good stream ID .. py:attribute:: status_code Status code .. py:class:: WindowUpdateFrame .. py:attribute:: stream_id Stream ID .. py:attribute:: delta_window_size Delta window size Exceptions ---------- .. py:class:: EOFError .. py:class:: CallbackFailureError .. py:class:: TemporalCallbackFailureError .. py:class:: InvalidArgumentError .. py:class:: ZlibError .. py:class:: UnsupportedVersionError .. py:class:: StreamClosedError Read Callback Flags ------------------- .. py:data:: READ_EOF Error Codes ----------- .. py:data:: ERR_INVALID_ARGUMENT .. py:data:: ERR_ZLIB .. py:data:: ERR_UNSUPPORTED_VERSION .. py:data:: ERR_WOULDBLOCK .. py:data:: ERR_PROTO .. py:data:: ERR_INVALID_FRAME .. py:data:: ERR_EOF .. py:data:: ERR_DEFERRED .. py:data:: ERR_STREAM_ID_NOT_AVAILABLE .. py:data:: ERR_STREAM_CLOSED .. py:data:: ERR_STREAM_CLOSING .. py:data:: ERR_STREAM_SHUT_WR .. py:data:: ERR_INVALID_STREAM_ID .. py:data:: ERR_INVALID_STREAM_STATE .. py:data:: ERR_DEFERRED_DATA_EXIST .. py:data:: ERR_SYN_STREAM_NOT_ALLOWED .. py:data:: ERR_GOAWAY_ALREADY_SENT .. py:data:: ERR_INVALID_HEADER_BLOCK .. py:data:: ERR_INVALID_STATE .. py:data:: ERR_GZIP .. py:data:: ERR_TEMPORAL_CALLBACK_FAILURE Following error codes indicate fatal error. .. py:data:: ERR_FATAL .. py:data:: ERR_NOMEM .. py:data:: ERR_CALLBACK_FAILURE Frame Types ----------- .. py:data:: SYN_STREAM .. py:data:: SYN_REPLY .. py:data:: RST_STREAM .. py:data:: SETTINGS .. py:data:: NOOP Note that this was deprecated in SPDY/3. .. py:data:: PING .. py:data:: GOAWAY .. py:data:: HEADERS .. py:data:: WINDOW_UPDATE This first appeared in SPDY/3. .. py:data:: CREDENTIAL This first appeared in SPDY/3. Control Frame Flags ------------------- .. py:data:: CTRL_FLAG_NONE Indicates no flags set. .. py:data:: CTRL_FLAG_FIN .. py:data:: CTRL_FLAG_UNIDIRECTIONAL Stream Status Codes ------------------- .. py:data:: OK This is not a valid status code for RST_STREAM. Don't use this in :py:meth:`Session.submit_rst_stream()`. .. py:data:: PROTOCOL_ERROR .. py:data:: INVALID_STREAM .. py:data:: REFUSED_STREAM .. py:data:: UNSUPPORTED_VERSION .. py:data:: CANCEL .. py:data:: INTERNAL_ERROR .. py:data:: FLOW_CONTROL_ERROR Following status codes were introduced in SPDY/3. .. py:data:: STREAM_IN_USE .. py:data:: STREAM_ALREADY_CLOSED .. py:data:: INVALID_CREDENTIALS .. py:data:: FRAME_TOO_LARGE GOAWAY Status Codes ------------------- .. py:data:: GOAWAY_OK .. py:data:: GOAWAY_PROTOCOL_ERROR .. py:data:: GOAWAY_INTERNAL_ERROR SETTINGS Frame Flags -------------------- .. py:data:: FLAG_SETTINGS_NONE .. py:data:: FLAG_SETTINGS_CLEAR_SETTINGS SETTINGS IDs ------------ .. py:data:: SETTINGS_UPLOAD_BANDWIDTH .. py:data:: SETTINGS_DOWNLOAD_BANDWIDTH .. py:data:: SETTINGS_ROUND_TRIP_TIME .. py:data:: SETTINGS_MAX_CONCURRENT_STREAMS .. py:data:: SETTINGS_CURRENT_CWND .. py:data:: SETTINGS_DOWNLOAD_RETRANS_RATE .. py:data:: SETTINGS_INITIAL_WINDOW_SIZE .. py:data:: SETTINGS_CLIENT_CERTIFICATE_VECTOR_SIZE .. py:data:: SETTINGS_MAX SETTINGS ID Flags ----------------- .. py:data:: ID_FLAG_SETTINGS_NONE .. py:data:: ID_FLAG_SETTINGS_PERSIST_VALUE .. py:data:: ID_FLAG_SETTINGS_PERSISTED