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dido:public:ra:xapend:xapend.f_qos:presentation [2021/08/13 12:40]
murphy
dido:public:ra:xapend:xapend.f_qos:presentation [2021/10/04 13:40] (current)
50.19.247.197 ↷ Links adapted because of a move operation
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 ====== F.6 Presentation ====== ====== F.6 Presentation ======
-[[dido:​public:​ra:​xapend:​xapend.f_qos| Return to DDS Quality of Service ]]+[[dido:​public:​ra:​xapend:​xapend.f_qos:start| Return to DDS Quality of Service ]]
  
 The PRESENTATION [[dido:​public:​ra:​xapend:​xapend.a_glossary:​q:​qos|QoS]] [[dido:​public:​ra:​xapend:​xapend.a_glossary:​p:​policy|policy]] controls the extent to which changes to data-[[dido:​public:​ra:​xapend:​xapend.a_glossary:​i:​instance|instances]] can be made dependent on each other and also the kind of dependencies that can be propagated and maintained by the Service. The PRESENTATION [[dido:​public:​ra:​xapend:​xapend.a_glossary:​q:​qos|QoS]] [[dido:​public:​ra:​xapend:​xapend.a_glossary:​p:​policy|policy]] controls the extent to which changes to data-[[dido:​public:​ra:​xapend:​xapend.a_glossary:​i:​instance|instances]] can be made dependent on each other and also the kind of dependencies that can be propagated and maintained by the Service.
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   * If ''​access_scope''​ is set to INSTANCE, the use of ''​begin_coherent_change''​ and ''​end_coherent_change''​ has no effect on how the [[dido:​public:​ra:​xapend:​xapend.a_glossary:​s:​subscriber|subscriber]] can access the data because with the scope limited to each instance, changes to separate instances are considered independent and thus cannot be grouped by a coherent change.   * If ''​access_scope''​ is set to INSTANCE, the use of ''​begin_coherent_change''​ and ''​end_coherent_change''​ has no effect on how the [[dido:​public:​ra:​xapend:​xapend.a_glossary:​s:​subscriber|subscriber]] can access the data because with the scope limited to each instance, changes to separate instances are considered independent and thus cannot be grouped by a coherent change.
-  * If ''​access_scope''​ is set to TOPIC, then coherent changes (indicated by their enclosure within calls to ''​begin_coherent_change''​ and ''​end_coherent_change''​) will be made available as such to each remote ''​DataReader''​ independently. That is, changes made to instances within each individual ''​DataWriter''​ will be available as coherent with respect to other changes to instances in that same ''​DataWriter'',​ but will not be grouped with changes made to instances belonging to a different ''​DataWriter''​.+  * If ''​access_scope''​ is set to [[dido:​public:​ra:​xapend:​xapend.a_glossary:​t:​topic|TOPIC]], then coherent changes (indicated by their enclosure within calls to ''​begin_coherent_change''​ and ''​end_coherent_change''​) will be made available as such to each remote ''​DataReader''​ independently. That is, changes made to instances within each individual ''​DataWriter''​ will be available as coherent with respect to other changes to instances in that same ''​DataWriter'',​ but will not be grouped with changes made to instances belonging to a different ''​DataWriter''​.
   * If ''​access_scope''​ is set to GROUP, then coherent changes made to instances through a ''​DataWriter''​ attached to a common ''​[[dido:​public:​ra:​xapend:​xapend.a_glossary:​p:​publisher|Publisher]]''​ are made available as a unit to remote subscribers.   * If ''​access_scope''​ is set to GROUP, then coherent changes made to instances through a ''​DataWriter''​ attached to a common ''​[[dido:​public:​ra:​xapend:​xapend.a_glossary:​p:​publisher|Publisher]]''​ are made available as a unit to remote subscribers.
  
dido/public/ra/xapend/xapend.f_qos/presentation.1628872809.txt.gz · Last modified: 2021/08/13 12:40 by murphy