[EDGENT-27] Additional documentation for publish-subscribe.

• Type: Test
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Component/s: Connectors, Documentation
• Assignee: Daniel John Debrunner
• Reporter: Daniel John Debrunner
• Created: 14/Mar/16 18:10
• Updated: 02/Mar/17 15:15

Description

From: https://github.com/quarks-edge/quarks/pull/98

generally +1 on all of this!

I think more doc is needed to inform users about the characteristics of the current impl:

Clarify there's no buffering/memory for tuples added to a topic: a published tuple is delivered only to current subscribers. The current wording focuses only on the no-subscribers case.
Must manually add a PublishSubscribeService to a provider instance to use this service. An example code fragment in the class would be beneficial.
The ProviderPubSub impl only works between topologies from the same provider instance
A publishing stream is isolated from its subscribers, and the subscribers from each other, via an implicit PlumbingStreams.isolate() on each subscribing stream. Users may want/need to manually insert a PlumbingStreams.pressureReliever() on subscriber streams to avoid excessive memory resource use from subscribers that can't keep up with the tuple production rate.
A sample demonstrating pub/sub use would be beneficial.