alexb at griffinbrown.co.uk
Mon Nov 1 11:57:54 CET 2010
Many thanks for doing this - this looks like an excellent basis for moving forward.
One thing that caught my eye is this opening words, which I hope this group will be able to work on unpacking a bit: "ZIP archive compression is a long-standing, widely-adopted technology described by PKWARE in their ZIP Application Note".
So, breaking this down:
> ZIP archive compression is a long-standing, widely-adopted technology ...
Might it be more correct to call Zip a "family" of technologies since, as we discussed on our last call, many variants are in use at any one time? Granted, it may be a closely related technology family, and may well exhibit a good deal of forwards-compatibility - but for newcomers coming to our work I think it's important to understand that we're not talking about "one spec; one implementation" but something a little subtler than that.
> ... described by PKWARE in their ZIP Application Note
The PKWare appnote is one description of Zip, a couple of others I can think of are the (derivative) Info-Zip series of app notes; and a further description of Zip is what existing application *do*, and what existing archives *contain* (and, in any contest between the written spec and existing practice, it is probably the case that the latter "wins"). Does anybody know of any other sources of Zip specification?
You mention in particular the Java Zip ecosystem. If we look at:
We see that "JAR format is based on the Info-ZIP file format" and from there we can follow a link to the Info-Zip application note 970331 (the link is dead, but I've put a live link on the Wiki). Unsurprisingly, this is the very same document which specifies the "Zip" of ISO/IEC 26300 (ODF 1.0). Later versions of the Info-Zip note describe the FOSS "Zip" tools that enjoy very wide use throughout the industry.
So, as I understand it, it is possible to create Zip archives that conform to PKWare's latest appnote that will not interoperate with tools/archives from (in this example) the Java Zip ecosystem ... this is why I think we need to be very careful about asserting that "Zip == PKWare appnote" without qualification - my Zip and your Zip may be different.
Does anybody have information about what the .NET ecosystem expects in its Zips? I imagine C/C++ programmers most usually reach for the Info-Zip libraries when using Zip ...
The other issue here is the mention of "*their* ZIP Application Note" in relation to PKWare. In the Tokyo WG 1 meeting there was quite some interest in the topic of whether/how the Zip specification was in the public domain, and in particular the wording of the press release copied at:
in which PKWare and Infinity Design Concepts Inc. wrote (rather wonderfully): "[t]he ZIP file format is given freely into the public domain and can be claimed neither legally nor morally by any individual, entity or company (or any other sentient creature in the universe.)" So I also think we need to be careful about asserting ownership of the format - might it be more correct (and neutral) to say that PKWare has played a major role in maintaining and extending a specification of the format?
From: sc34wg1study-bounces at vse.cz [mailto:sc34wg1study-bounces at vse.cz] On Behalf Of Andrew Rist
Sent: 29 October 2010 21:44
To: ISO Zip
I have taken as my task to list the root problems associated with the use of the ZIP format in document format standards.
This task does not involve the suggestion or prescription of any particular solution, and includes the understanding that WG1, SC34, or even ISO may not be the suitable forum to resolve these issues.
The following is what I have put up on the WG1 wiki, we can develop it further there. Please limit edits to focus on identifying the problem and not to define solutions. (for this section of the wiki, of course)
ZIP archive compression is a long-standing, widely-adopted technology described by PKWARE in their ZIP Application Note. This technology is used for many purposes in the industry, from the archiving and compression of files to packaging of applications (Java jar/ear/war).
Additionally, in recent years there have been a number of document format standards that use ZIP as a "container file" for storing XML and related resources. For example, OASIS ODF (ISO/IEC 26300), Ecma OOXML (ISO/IEC 29500), IDPF EPUB and W3C Widgets.
This use of the ZIP Application Note, as an external normative reference, by International Standards or specifications which may be on the track to become International Standards, presents the following problems:
* There is no Standards Compatible Reference associated with the .ZIP Application Note.
* There is an ambiguous IPR landscape, especially related to the IPR referenced in the .ZIP Application Note.
* There are technical issues related to the use of ZIP as a document package which are not covered by the .ZIP Application Note
* ZIP is a ubiquitous and highly interoperable technology, and any standards activity relating to ZIP should not negatively impact the current use of ZIP or its current use in standards.
As back up to the main problems identified above, here are a set of more specific issues that fall under these categories:
* No Standards Compatible Reference
* Current Application Note is not referenceable by International Standards
* There is no mechanism to reference parts of the Application Note
* There is ambiguity in terms of the future maintenance of the Application Note (e.g. feedback procedures and transparency)
* Ambiguous IPR Landscape
* It is not possible to identify which parts of the Application Note are subject to IP and which are not
* The use of ZIP in Open Standards (which are implementable in all Open Source) requires any IP used in the standards to be licensed under RF terms.
* Technical Issues related to the use of ZIP as a Document Package
* Minimum feature set relevant to all document packaging use of ZIP
* additional syntax
* additional objects and metadata
* signatures and encryption
* ZIP URL protocol & fragment identifiers
* Do No Harm to the Current Usage of ZIP
* Ubiquitous nature of ZIP creates wide reaching benefits (utilities built into all development platforms and OSes)
* Currently in use by wide range of standards
* ODF, OOXML, EPUB
* W3C widgets
* Java (jar, war, ear, java.util.zip)
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Andrew Rist | Interoperability Architect
Oracle Corporate Architecture Group
Redwood Shores, CA | 650.506.9847
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