Call for implementation ideas

The Process requires that we have criteria to enter PR (aka "CR exit 
criteria"). This seems like the right time to consider these since the 
adopted requirements seem likely to affect decisions in the LC period 
e.g. how likely we are to cut or mark as "at risk" features due to lack 
of implementation.

The process document says that, in order to enter PR, one must:

"""1. Fulfilled the general requirements for advancement;

2. Shown that each feature of the technical report has been implemented. 
Preferably, the Working Group SHOULD be able to demonstrate two 
interoperable implementations of each feature. If the Director believes 
that immediate Advisory Committee review is critical to the success of a 
technical report, the Director MAY accept to Call for Review of a 
Proposed Recommendation even without adequate implementation experience;

3. Satisfied any other announced entrance criteria (e.g., any included 
in the request to advance to Candidate Recommendation, or announced at 
Last Call if the Working Group does not intend to issue a Call for 
Implementations)."""

I believe the CSS WG considered 2. to be "two UAs that interoperably 
implement all features". This is to ensure that the spec can't reach PR 
with UAs A and B implementing subset X of the features and C+D 
implementing subset Y but implementing the union X|Y being impossible. I 
think this makes sense although it is a considerably higher bar than 
just having two implementations of all features.

In any case we also need tests for all features. The stated CSS policy 
seemed to be to drop features that didn't have sufficient tests.

In general, it should be noted that dropping features isn't necessarily 
easy. For example if we can't get two perfectly interoperable 
implementations of the exact details of how script scheduling works, it 
isn't possible to just pull that feature from the spec wholesale without 
a huge amount of work and a huge amount of undefined behavior. So there 
needs to be scope to compromise on the requirements or the timeline.

Received on Tuesday, 17 May 2011 08:42:25 UTC