==== Topic ====

A **Topic** is the most basic description of data that is to be published 
and/or subscribed to.  A topic connects a [[ddsf:public:guidebook:06_append:glossary:d:data_writer]] with 
a [[ddsf:public:guidebook:06_append:glossary:d:data_reader]], i.e., communication does not occur unless the 
topic published by a data writer matches a topic subscribed 
to by a data reader. Communication via topics is anonymous 
and transparent, i.e., publishers and subscribers need not 
be concerned with how topics are created or who is 
writing/reading them since the [[ddsf:public:guidebook:06_append:glossary:d:data_distribution_service_dds]] [[ddsf:public:guidebook:06_append:glossary:d:dcps|DCPS]] [[ddsf:public:guidebook:06_append:glossary:m:midware|middleware]] manages 
these issues.  In programming terms, a Topic is a Class 
and each [[ddsf:public:guidebook:06_append:glossary:i:instance|instance]] is a [[ddsf:public:guidebook:06_append:glossary:s:sample|Sample]]. Topic instances are associated 
with a [[ddsf:public:guidebook:06_append:glossary:k:key|key]] (similar to a packet [[ddsf:public:guidebook:06_append:glossary:i:id|ID]]), defined by [[ddsf:public:guidebook:06_append:glossary:i:idl]] and a 
set of Quality of Service parameters.


Source: [[https://istkb.adlinktech.com/article/vortex-opensplice-dds-glossary/ | OpenSplice Glossary]]