GPR-019 — Implementation Replacement Without Client Changes

Go to Annex C: Requirements

An implementation SHOULD be replaceable by an alternative implementation satisfying the same applicable Interface Contracts and conformance conditions without requiring changes to conforming clients.

Recommended

Replacement without client changes reduces implementation coupling, migration cost, operational disruption, and dependence on a particular product or vendor.

A conforming client should depend on standardized Interfaces, externally observable behavior, and applicable conformance conditions rather than implementation-specific behavior or internal design choices.

A Submission satisfying this recommendation demonstrates that:

1. Applicable Interface Contracts and conformance conditions are sufficient to support implementation replacement
2. Conforming clients depend only on standardized Interfaces and externally observable behavior
3. Replacing an implementation with a conforming alternative does not require changes to conforming clients
4. Implementation-specific extensions are distinguishable from standardized capabilities
5. Dependencies that could prevent implementation replacement are identified
6. Any departure from this recommendation is identified and justified

This requirement uses SHOULD and is therefore a recommendation.

The requirement applies when the original and replacement implementations satisfy the same applicable Interface Contracts and conformance conditions.

A client that depends on implementation-specific extensions, undocumented behavior, or capabilities outside the proposed specification may require changes when the implementation is replaced. Such a client is not conforming with respect to those dependencies.

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