node config

per-node config specification

Node configuration determines:

• flow versioning
• resource page and resource fragment generation
• distribution syntaxes
• template usage and stylesheets
• attribution defaults

Node configuration is held in memory by the flow service (Private), and is calculated when the service starts.

Node configuration is at least partially determined by "config specification", which happens in meshnode config flows and can be inherited to contained nodes.

If config specification is missing, (i.e., config spec inheritance is turned off or unspecified), node configuration will be determined from service-level config specification, i.e. product.service.config (Private). In case there is none, the service will use sensible defaults at the root level which will be inherited down the mesh.

Initial Config Specification

• When a node is initially created, if config-defaults-inheritance is turned on for its parent node, it will have its meshnode config flows populated based on any parent Node Config Defaults files present in the hierarchy. If there are none, its current snapshot will not be created.

Calculating Node Config

When the sflo-host starts, it calculates non-default config settings for every node.

• determines the "default" settings for this service instance from product.service.config (Private)
• if the node has a meshnode config flows , the service will use any settings there that differ from its defaults
• if config-inheritance is turned on for a node, the service will scan back up the hierarchy to compose any missing "non-default" settings
• the result is an in-memory "shadow mesh" known as the product.service.components.node-config-map (Private) containing any non-default settings for the mesh

If calculated config matches the service defaults, they are ignored.

per-service settings for node defaults

• product.service.config (Private) can establish any mesh-wide settings that diverge from the system defaults

platform node-config defaults

Semantic Flow uses sensible defaults, specified in the so that neither node-level nor service-level "non-default" settings are necessary

• by default:
  • versioning is turned on for all flows
  • distribution syntaxes are .trig and jsonld
  • resource pages are generated using a standard template and CSS file that get copied into a mesh repo's root assets tree upon initialization
  • Aggregated Distribution are not generated
  • concept.mesh.resource.element.flow.unified (Private)