NEW ISSUE: Limit policySet attachment to bindings

Title: NEW ISSUE: Limit policySet attachment to bindings

TARGET: SCA Policy Framework Specification

DESCRIPTION:

[This issue is concerning interaction policies only]

PolicySets are used to apply particular policies to the binding of a service or reference. 

Currently, the specification allows attaching PolicySets to any element in the SCDL e.g interface element or other nodes higher than the binding element. While such a flexibility may simplify SCDL documents in some cases, it also leads to the following potential issues:

- limitation on the range of bindings that can be used

- conflicting policySets for any given binding and the complexity of rules for resolving the conflicts

PROPOSAL:

Restrict application of policy sets to binding elements only.