====== F.15 Transport Priority ======
[[dido:public:ra:xapend:xapend.f_qos:start| Return to DDS Quality of Service ]]

The [[dido:public:ra:xapend:xapend.a_glossary:t:transport_priority|TRANSPORT_PRIORITY]] [[dido:public:ra:xapend:xapend.a_glossary:q:qos|QoS]] policy allows the [[dido:public:ra:xapend:xapend.a_glossary:a:application|application]] to take advantage of transports capable of sending messages with different priorities.

This [[dido:public:ra:xapend:xapend.a_glossary:p:policy|policy]] is considered a hint. The policy depends on the ability of the underlying transports to set a priority on the messages they send. Any value within the range of a [[dido:public:ra:xapend:xapend.a_glossary:00-9:32bit]] signed integer may be chosen; higher values indicate higher priority. However, any further interpretation of this policy is specific to a particular transport and a particular implementation of the Service. For example, a particular transport is permitted to treat a range of priority values as equivalent to one another. It is expected that during transport configuration the application would provide a mapping between the values of the TRANSPORT_PRIORITY set on ''DataWriter'' and the values meaningful to each transport. This mapping would then be used by the infrastructure when propagating the data written by the ''DataWriter''.

Source: [[https://www.omg.org/spec/DDS/1.4/PDF | DDS 1.4 Spec]]

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