Notice: This Wiki is now read only and edits are no longer possible. Please see: https://gitlab.eclipse.org/eclipsefdn/helpdesk/-/wikis/Wiki-shutdown-plan for the plan.
HGraph
Motivation
The initial motivation for HGraph was to address a number of limitations of IdAS 1.1 related to describing and managing metadata.
Higgins-based applications have a requirement to be able to conveniently describe and manage metadata about regular entities. Examples include the need to cleanly separate provenance metadata entities from the base entities, or the need to be able to associate a set of attributes with a complex-valued (link-valued) attribute.
Imaging we have two contexts both of which make statements about entity e1. In the left-hand context, for which the RMV is the authority, we have the statement (e1 eye-color "blue") whereas in the right-hand context, for which the State Department is authoritative we have the statement (e1 eye-color "green"). These two authorities disagree about e1's eye color.
In IdAS this would be represented as follows:
This is currently quite awkward to achieve with IdAS 1.1. IdAS 1.1 can be thought of as context-centric. Whereas the authoritative context for a given entityId (aka a UDI) can be discovered dynamically, there is no easy and fast way to assemble all of the other (non-authoritative) contexts that may also make statements about a given entity (of the same entityId). In practice this is sufficiently awkward that the general IdAS idiom is to simply not do so, and to only have a single context for information about an entity. In practice a given entityid typically only occurs in a single context--its authoritative context.
...TODO show how the above example can be described in IdAS 1.1
...to be continued