The basic assumption for these header layouts is that the data layout in the published messages is static. This implies the following:
- Each NetworkMessagecontains the same number of DataSetMessages
- The sequence of the DataSetMessageswithin a NetworkMessageis the same in every PublishingInterval
- The layout of the fields within every DataSetMessageis the same in every PublishingInterval
Subscribershave to know the static message layout in advance. This means all fields in the headers which would be required for ad-hoc parsing of messages with dynamic layout can be omitted (e.g. PayloadHeaderor Sizes).
PublisherIdand WriterGroupIdidentify the WriterGroup. The NetworkMessageNumberis important for WriterGroupswhich distribute their DataSets over more than one NetworkMessage, and the GroupVersionallows the Subscriberto verify the expected layout of the DataSetMessagesand their DataSet fields.