DynamicData examples

How to publish and subscribe to topics for dynamically-defined types.

How to publish and subscribe to topics for dynamically-defined types.

In addition to IDL and code generation, data types can be defined dynamically in code and in XML using Rti.Types.Dynamic.DynamicType. Data for those types can be published and subscribed to using Rti.Types.Dynamic.DynamicData.

Example 1: define a type and publish a data sample

 
    // Define the Shape type dynamically:
    var typeFactory = Rti.Types.Dynamic.DynamicTypeFactory.Instance;
    StructType shapeType = typeFactory.BuildStruct()
        .WithName("Shape")
        .AddMember(new StructMember("color", typeFactory.CreateString(bounds: 128), isKey: true))
        .AddMember(new StructMember("x", typeFactory.GetPrimitiveType<int>()))
        .AddMember(new StructMember("y", typeFactory.GetPrimitiveType<int>()))
        .AddMember(new StructMember("shapesize", typeFactory.GetPrimitiveType<int>()))
        .Create();
 
    // Create a topic for the type we have defined. The generic type argument
    // for Topic is DynamicData when we call CreateTopic with a DynamicType.
    Topic<DynamicData> topic = participant.CreateTopic(
        name: "Square",
        type: shapeType);
 
    // Create a DataWriter
    DataWriter<DynamicData> writer = participant.ImplicitPublisher
        .CreateDataWriter(topic);
 
    // Create a sample
    DynamicData sample = new DynamicData(shapeType);
 
    // writer.CreateData() has the same effect:
    DynamicData sample2 = writer.CreateData();
 
    // Set the fields by name
    sample.SetValue(memberName: "color", value: "GREEN");
    sample.SetValue(memberName: "shapesize", value: 40);
 
    // Or by member index (which is more efficient)
    sample.SetValue(memberId: 2, value: 100); // sample.x = 100
    sample.SetValue(memberId: 3, value: 100); // sample.y = 100
 
    // The type of the argument value must match exactly the declared field
    // type. For convenience, SetAnyValue will attempt to transform the
    // intput value to the declared type. In this example it will convert
    // the string "17" to an the int 17.
    sample.SetAnyValue(memberName: "x", value: "17");
 

Example 2: load a type definition from XML and subscribe to it

 
    static void ProcessData(AnyDataReader anyReader)
    {
        var reader = (DataReader<DynamicData>)anyReader;
        using var samples = reader.Take();
        foreach (var sample in samples)
        {
            if (sample.Info.ValidData)
            {
                DynamicData data = sample.Data;
 
                // Get the fields using member name or member index
                string color = data.GetValue<string>(memberName: "color");
                int shapesize = data.GetValue<int>(memberName: "shapesize");
                var coordinates = (
                    data.GetValue<int>(memberId: 2), // data.x
                    data.GetValue<int>(memberId: 3)  // data.y
                );
 
                // The type argument for GetValue must exactly match the declared
                // field type. You can use GetAnyValue to return an object instead
                object colorAsObject = data.GetAnyValue("color");
 
                // You can also convert the data to string
                Console.WriteLine(data);
            }
        }
    }
 
    // Load the ShapeType from an XML file
    var provider = new QosProvider("Shape.xml");
    DynamicType shapeType = provider.GetType("Shape");
 
    // Create a topic for the type we have defined. The generic type argument
    // for Topic is DynamicData when we call CreateTopic with a DynamicType.
    Topic<DynamicData> topic = participant.CreateTopic(
        name: "Square",
        type: shapeType);
 
    // Create a DataReader with an event handler for DataAvailable
    DataReader<DynamicData> reader =
        participant.ImplicitSubscriber.CreateDataReader(
            topic,
            preEnableAction: reader => reader.DataAvailable += ProcessData);
 
    // ...
 

The XML definition of the Shape type is:

<?xml version="1.0" encoding="UTF-8"?>
<dds xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:noNamespaceSchemaLocation="https://community.rti.com/schema/current/rti_dds_profiles.xsd">
  <types>
    <module name="Example">
      <struct name= "Shape">
        <member name="color" stringMaxLength="128" type="string" key="true"/>
        <member name="x" type="int32"/>
        <member name="y" type="int32"/>
        <member name="shapesize" type="int32"/>
      </struct>
    </module>
  </types>
</dds>

The rticonnextdds-examples GitHub repository provides additional DynamicData examples

• Dynamic Data Publisher and Subscriber
• Dynamic Data Sequences