DDSPSMC — XML-Based QoS Policy Settings (DDS-PSM-Cxx/DDS-PSM-Java)

The newly introduced XML Based Policy configuration adds new methods in the core DDS entities that allow to fetch QoS from XML filers. This solution is not ideal since if generalized, e.g. QoS configuration from an URI, JSON stream, etc., would lead to an explosion of the core DDS API.

The suggestion is to remove the added methods from the core API and use instead a Builder pattern (of some form).

A sketch of the suggested change is provided below:

PolicyBuilder builder = PolicyBuilder::load("XMLBuilder");

TopicQos tqos = builder.topic_qos(file_name, profile_name);

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Notice that the suggested approach allows to easily extend the supported format for QoS representation w/o any impact on the core DDS API and overall facilitate the support for multiple approaches.

The class dds::core::qos::TQoSProvider provider has been added to the C++ API to allow the external configuration of QoS. Section 7.6.2.1 of the specification document has been updated accordingly to describe the dds::core::TQoSProvider