A DataSetMessageis created from a DataSet. It consists of a header and the encoded fields of the DataSet.

Depending on the configured DataSetMessageContentMask, a DataSetMessagemay exist in different forms and with varying detail.DataSetMessagesdo not contain any information about the data acquisition or information source in the Publisher.

Additional header information includes:

DataSetWriterIdIdentifies theDataSetWriterand indirectly the PublishedDataSet.

Sequence numberA number that is incremented for each DataSetMessage. Can be used to verify the ordering and to detect missing messages.

TimestampA timestamp describing when the data in this DataSetMessagewas obtained.

VersionVersion information about the configuration of the DataSetMetaData.

StatusStatus information about the data in this DataSetMessage.

Keep aliveWhen no DataSetMessagesare sent for a configured time period, a keep alive DataSetMessageis sent to signal the Subscribersthat the Publisheris still alive.

DataSetMessagesare either sent cyclicly or acyclicly in a publishing interval. Acyclic DataSetsare sent as event DataSetMessages. Cyclic DataSetscan create at most one DataSetMessagesper interval. Acyclic DataSetscan create multiple event DataSetMessagesper interval.

For cyclic DataSets, some encodings differentiate between key frame DataSetMessages and delta frame DataSetMessages. A key frame DataSetMessageincludesvalues forall fields of the DataSet.A delta frame DataSetMessageonly contains the subset that changed since the previous DataSetMessage.

A key frame DataSetMessageis sent after a configured number of DataSetMessages.

The DataSetMetaDataas data contract defines the fields contained in the DataSetMessage. The header settings for DataSetMessageand NetworkMessagedefine the communication contract between Publisherand Subscriber.

A heartbeat DataSetMessageis a key frame that only contains header information. It is used to indicate that the Publisheris still alive without sending payload. A heartbeat DataSetMessageis not created from a DataSet.