DDS_TypeSupportQosPolicy Struct Reference

Allows you to attach application-specific values to a DDS_DataWriter or DDS_DataReader, which are passed to the serialization or deserialization routine of the associated data type and choose whether to set padding bytes to zero during serialization. More...

Data Fields
void *	plugin_data
	Value to pass into the type plugin's de-/serialization function.
DDS_CdrPaddingKind	cdr_padding_kind
	Determines whether or not the padding bytes will be set to zero during CDR serialization.

Detailed Description

Allows you to attach application-specific values to a DDS_DataWriter or DDS_DataReader, which are passed to the serialization or deserialization routine of the associated data type and choose whether to set padding bytes to zero during serialization.

The purpose of this QoS is to allow a user application to pass data to a type plugin's support functions and choose whether or not to set the padding bytes to zero when serializing a sample using CDR encapsulation.

Entity:

DDS_DomainParticipant, DDS_DataReader, DDS_DataWriter

Properties:

RxO = NO

Changeable = UNTIL ENABLE

Usage

The DDS_TypeSupportQosPolicy::plugin_data allows you to associate a pointer to an object with a DDS_DataWriter or DDS_DataReader. This object pointer is passed to the serialization routine of the data type associated with the DDS_DataWriter or the deserialization routine of the data type associated with the DDS_DataReader.

You can modify the rtiddsgen-generated code so that the de/serialization routines act differently depending on the information passed in via the object pointer. (The generated serialization and deserialization code does not use the pointer.)

This functionality can be used to change how data sent by a DDS_DataWriter or received by a DDS_DataReader is serialized or deserialized on a per DataWriter and DataReader basis.

It can also be used to dynamically change how serialization (or for a less common case, deserialization) occurs. For example, a data type could represent a table, including the names of the rows and columns. However, since the row/column names of an instance of the table (a Topic) don't change, they only need to be sent once. The information passed in through the TypeSupport QoS policy could be used to signal the serialization routine to send the row/column names the first time a DDS_DataWriter calls FooDataWriter_write, and then never again.

The DDS_TypeSupportQosPolicy::cdr_padding_kind allows you to choose whether or not the padding bytes are set to zero during CDR serialization.

Field Documentation

void* DDS_TypeSupportQosPolicy::plugin_data

Value to pass into the type plugin's de-/serialization function.

[default] NULL

DDS_CdrPaddingKind DDS_TypeSupportQosPolicy::cdr_padding_kind

Determines whether or not the padding bytes will be set to zero during CDR serialization.

In a DomainParticipant, this value configures how the padding bytes are set when serializing data for the Built-In Topic DataWriters and DataReaders. A value of DDS_AUTO_CDR_PADDING defaults to DDS_NOT_SET_CDR_PADDING.

For DataWriters and DataReaders, this value configures how padding bytes are set when serializing data for that entity. A value of DDS_AUTO_CDR_PADDING means that the entity will inherit whatever value is set on the DomainParticipant.

[default] DDS_AUTO_CDR_PADDING