Requirements for Metadata Repositories Registries Directories

This Wiki page is for collecting text that is following on with discussion at the Workshop on IoT Semantic/Hypermedia Interoperability in Prague, 2017-07. Specifically, this page is addressing:

How can metadata repositories/registries/directories be most useful for collaboration and use?
Types of repos, e.g., classes vs. instances etc.

E.g., OCF (Michael M), iotschema, openfog, WoT (Kaz), Haystack (Milan), YANG repositories (Alex)

Directory – Example: WoT Thing Directory

Used to register entry points to instances and affordances of connected things
Used in Discovery to locate entry points of interesting connected things and services
Enables both intrinsic and late binding (extrinsic) annotation to be used for selective discovery

Used to obtain common terminology to annotate instances and affordances of connected things
Contains vocabularies and ontological graphs that provide meaningful information about the affordances that use the annotations
Well-known place to obtain definitions for terms
Machine- and Human-readable formats
Provide meaningful information about terms
Common Core vocabulary for base interoperability
Domain-agnostic vocabulary support
Protocol-agnostic formats
Permissive licensing for contributions and use of content
Easy to contribute to and maintain from diverse application domains