4.2. DDS Entities¶
The main classes extend an abstract base class called a DDS Entity. Every DDS Entity has a set of associated events known as statuses and a set of associated Quality of Service Policies (QosPolicies). In addition, a Listener may be registered with the Entity to be called when status changes occur. DDS Entities may also have attached DDS Conditions, which provide a way to wait for status changes. Figure 4.1: Overview of DDS Entities presents an overview in a UML diagram.
![../_images/EntitiesUML.png](../_images/EntitiesUML.png)
Figure 4.1 Overview of DDS Entities
Please note that RTI Connext DDS Micro does not support the following:
- MultiTopic
- ContentFilteredTopic
- ReadCondition
- QueryConditions
For a general description of DDS Entities and their operations, please refer to the DDS Entities chapter in the RTI Connext DDS Core Libraries User’s Manual (available here if you have Internet access). Note that RTI Connext DDS Micro does not support all APIs and QosPolicies; please refer to the C API Reference and C++ API Reference documentation for more information.