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IDProjectCategoryView StatusDate SubmittedLast Update
000535210000-014: PubSubSpecpublic2019-12-13 16:522021-11-02 08:59
ReporterMatthias Damm Assigned ToMatthias Damm  
PriorityhighSeverityfeatureReproducibilityhave not tried
Status assignedResolutionopen 
Summary0005352: Enhanced PubSub discovery concepts needed
Description

Based on the discussions in the December 2019 F2F meeting in Phoenix we need to work on enhanced PubSub discovery concepts.
See meeting minutes and meeting folder for more information and presentations.

The following requirements / missing parts were discussed

Scope of PublisherId

PublisherId must be unique the scope of the NetworkAddress. Global discovery requires PublisheIds (or other options e.g. ApplicationInstanceUri) that are unique in the global discovery scope

Topic discovery

Publishers provide streams of data defined through DataSetMetaData and delivered through NetworkMessags.
If we define the concept of Topics, a Topic would either represent a message type (DataSetMetaData class) or a message writer instance.
A Topic discovery must support a global Topic tree or even Topic mesh network discovery.

Late binding of NetworkAddress

Publisher and Subscribers may be configured in general but without a concrete definition of the NetworkAddresses.
Use cases are dynamic multi-cast IP assignment or TSN stream assignment.

TagsNo tags attached.
Commit Version
Fix Due Date

Relationships

related to 0005038 closedMatthias Damm Add missing discovery options 

Activities

Matthias Damm

2020-06-19 10:37

developer   ~0012464

Added first extensions for review.

Added in OPC 10000-14 - UA Specification Part 14 - PubSub Draft 1.05.27.docx

Matthias Damm

2021-11-02 08:59

developer   ~0015244

Added the following definition in OPC 10000-14 - UA Specification Part 14 - PubSub 1.05.1 Draft40.docx

7.2.2.6.2 Discovery scope
Discovery in a global scope requires unique PublisherIds. Publishers shall use the default PublisherIds as defined in 6.2.6.1 for the following discovery messages.
• OPC UA Application information announcement
• Publisher endpoint announcement
• PubSubConnection configuration announcement
These messages use the standard discovery address if defined for the transport protocol mapping like the IANA registered IPv4 multicast address for UDP.
Other announcements below PubSubConnection level can use different PublisherIds for different transport protocol mappings. Such a PubSubConnection specific PublisherIds could be a two Byte PublisherId for Ethernet transport protocol mapping. These PublisherIds are known from the payload of the PubSubConnection configuration announcement messages.

This covers part of this issue and was necessary to complete the related additions for 0005038

Other parts like Topic discovery are not complete yet. We added a topic field to extended UADP message mapping structure DataTypes but this information is not availale in all places yet and we need a central look-up service to find Publishers based on a topic.

Issue History

Date Modified Username Field Change
2019-12-13 16:52 Matthias Damm New Issue
2019-12-13 16:52 Matthias Damm Status new => assigned
2019-12-13 16:52 Matthias Damm Assigned To => Matthias Damm
2019-12-13 16:58 Matthias Damm Description Updated
2020-06-19 10:37 Matthias Damm Note Added: 0012464
2020-06-19 10:40 Matthias Damm Relationship added related to 0005038
2021-11-02 08:59 Matthias Damm Note Added: 0015244