RE: Restricting relationship types to node types and node types with cap

Hi Paul,

Iâm attaching a very rudimentary TOSCA template that starts to implement your pattern for the SID Metric ABE. It shows how relationship types can be refined by limiting valid_target_types to derived types of the NodeExtension capability type.

Iâd love to work with you to flesh this out further if youâre interested.

Thanks,

Chris

From: Chris Lauwers
Sent: Sunday, November 29, 2020 6:15 PM
To: paul.m.jordan@bt.com; tosca-comment@lists.oasis-open.org
Subject: RE: Restricting relationship types to node types and node types with capability types.

Thanks Paul, weâll take this up for review. In the meantime, a couple of additional comments:

If we were to rename the âvalid_target_typesâ keyword, then perhaps âvalid_target_capability_typesâ may be the more accurate description.
As we discussed, I believe your pattern can be supported by subclassing capability types. You mentioned that might be too cumbersome, but Iâll try to work through your example to get a feel for how bad it really is 😊

Thanks again for all your helpful feedback.

Chris

From: tosca-comment@lists.oasis-open.org <tosca-comment@lists.oasis-open.org> On Behalf Of paul.m.jordan@bt.com
Sent: Wednesday, November 25, 2020 3:19 AM
To: tosca-comment@lists.oasis-open.org
Subject: [tosca-comment] Restricting relationship types to node types and node types with capability types.

At present relationship type definitions may contain a restriction to limit their application to node types which contain one or more of the specified capability types. Currently the name of this keyword is valid_target_types which is somewhat inaccurate and could be confusing.

Furthermore I have a pattern for node extension which would benefit from an additional limitation on relationship types so that they were only applicable to specified node types.

Therefore I propose that relationship type definition is amended as follows:

Keyname	Required	Definition/Type	Description
â
valid_target_types	No	list of string	This keyname is deprecated; valid_target_node_capabilities is now preferred. An optional list of one or more names of Capability Types that must exist within nodes which are valid targets for this relationship. If undefined, target nodes may have any or no Capability Types defined.
valid_target_node_capabilities	no	list of string	An optional list of one or more names of Capability Types that must exist within nodes which are valid targets for this relationship. If undefined, target nodes may have any or no Capability Types defined.
valid_target_node_types	no	list of string	An optional list of one or more names of Node Types that are valid targets for this relationship. If undefined, all Node Types are valid targets.

If both valid_target_node_types and valid_target_node_capabilities are specified then they would be ANDed, i.e. the relationship type would be applicable only to a nodes of the specified type if it had one or more of the specified capabilities.

Paul Jordan
OSS Specialist
BT Technology | Tel +44 (0) 3316252643 | paul.m.jordan@bt.com

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