Sending Only a Few Fields

In some cases, your data model may contain a large number of potential fields, but it may not be desirable or appropriate to include a value for every one of them with every DDS data sample.

• It may use too much bandwidth. You may have a very large data structure, parts of which are updated very frequently. Rather than resending the entire data structure with every change, you may wish to send only those fields that have changed and rely on the recipients to reassemble the complete state themselves.
• It may not make sense. Some fields may only have meaning in the presence of other fields. For example, you may have an event stream in which certain fields are only relevant for certain kinds of events.

To support these and similar cases, Connext DDS supports mutable types and optional members (see the RTI Connext DDS Core Libraries Getting Started Guide Addendum for Extensible Types).

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