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Query Message

  • Protocol Version: 3.0
  • Release Date: January 20, 2017

Simple Querying Mechanism

In OpenIGTLink version 2, special prefixes GET_, STT_, STP_, and RTS_ are used in the message type field in the header for messages to query and control data flow. Those messages with those special prefix should be defined along with primary message types (for example, STT_TDATA, STP_TDATA and RTS_TDATA should be defined with TDATA).

GET_ prefix: Query a single message

"GET_<datatype>" query message is used to request for a single message with type <datatype>. The receiver of "GET_<datatype>" message must return a message with type <datatype> and the same name as the query message. A "GET_<datatype>" message without device name requests any available data. If data is not available, a returned message must be null body (data size = 0). A format of "GET_<datatype>" may be defined per data type, if necessary.

STT_ and STP_ prefixes: Control data flow

"STT_<datatype>" and "STP_<datatype>" query message is used to request to start and stop sending a series of messages. The receiver of "STT_<datatype>" or "STP_<datatype>" message must return "RTS_<datatype>" message with the same name as the query message to notify that the receiver receives the query. Formats of "STT_<datatype>", "STP_<datatype>" and "RTS_<datatype>" may be defined per data type, if necessary.

Available Message Type (Including sub-types)

Type name GET query STT query STP query RTS message Description
IMAGE GET_IMAGE STT_IMAGE STP_IMAGE RTS_IMAGE 2D/3D image data
TRANSFORM GET_TRANSFOR STT_TRANSFOR STP_TRANSFOR RTS_TRANSFOR Affine transform data.
POSITION GET_POSITION STT_POSITION STP_POSITION RTS_POSITION Position and orientation (quaternion)
CAPABILITY GET_CAPABIL -- -- RTS_CAPABIL Points or fiducials.
STATUS GET_STATUS -- -- RTS_STATUS Device status
TDATA GET_TDATA STT_TDATA STP_TDATA RTS_TDATA Tracking data
IMGMETA GET_IMGMETA -- -- RTS_IMGMETA List of image meta data including patient name, ID (medical record number), size, etc.
LBMETA GET_LBMETA -- -- RTS_LBMETA List of label meta data.
POINT GET_POINT -- -- RTS_POINT Points or fiducials.
TRAJ GET_TRAJ -- -- RTS_TRAJ Trajectory data (needle path etc.)
NDARRAY GET_NDARRAY STT_NDARRAY STP_NDARRAY RTS_NDARRAY Associative array to transfer a set of values with key names.
COMMAND -- -- -- RTS_COMMAND Command