Clarify relationship with Publishing WG’s Packaged Web Publications

[js-choi]

Several days ago, the W3C Publishing WG published three working drafts, including Packaged Web Publications (WPub/PWP), which defines a packaging format for combining collections of resources into a single portable WPUB file.

This WPub standard seem to be quite similar to this WICG–IETF Web Packages (WPK) standard. But the relationship between the two is unclear.

I could find some references to the Publishing WG here. Web Packaging Format’s use-cases note has a “Packaged Web Publications” in its “Nice-to-have” section; it refers to the Publishing WG and discusses several abstract use cases provided by the WG, without actual reference to WPub as a specification. Several issues here (#3 “Relationship to DPUB”, #32 “Document Adobe’s use cases”, #37 “Add a list of goals and non-goals”, #71 “Start an internet-draft”) also refer to the Publishing WG. Some Publishing WG members (@lrosenthol, @iherman, @dauwhe) have participated in these issues.

None of these references talk about WPub as a separate specification, and none of them elaborate on its relationship with Web Packaging Format. Neither the Web Packaging specification itself nor the obsolete TAG Packaging on the Web draft make any mention of WPub either.

This is triply confusing. There is clear overlap between the two specifications’ use cases. For instance, both initiatives appear to desire addressing Google AMP’s use cases. Even their names are confusingly similar (WPK vs. PWP). Both are being actively developed—there were even announcements regarding both on this same week (the WPub public-draft announcement and the Google AMP Project’s announcement on its transition to WPK). And some of the same people have participated in both discussions on one standard and discussions on the other.

For readers of both specifications, it would be useful if their authors clarified this uncertainty. “What is the relationship between the two standards?” “Why are there two separate standards?” “How are their use cases and file formats similar and different?” Further active collaboration between the two specs’ authors might also be worth pursuing. Though it might be too late for unification, it would be a shame if there was fragmentation of the same goal into two formats. Browser vendors are probably less likely to implement two formats than just one. On the other hand, if their use cases are irreconcilable, then that should be made explicit in the specifications.

(Also cf. w3c/wpub#5 (comment), w3c/wpub#5 (comment) by @HadrienGardeur; as well as w3c/wpub#10, w3c/wpub#90, and w3c/wpub#111.)

[js-choi]

I realized that it may be more appropriate to raise this issue in w3c/wpub, since WPub/PWP addresses more specific use cases than WPK does. I raised w3c/wpub#120 and will close this issue for now.