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Posted by: Marbux (Friday 29 February 2008, 7:03 PM)

OOXML interop is abysmal

Albert, thank you for acknowledging that OOXML interop is application-level rather than being enabled and required by the format specifications. The same phenomenon is seen with ODF. So perhaps we can now begin a productive discussion.

But the fact that interop is at the application level, requiring e.g., scripts, custom schemas, ribbon extensions, etc. to make it work as with the Mindjet "mind-mapping" tool is a bug, not a feature.

One huge problem with both OOXML and ODF is that neither specifies an interoperability framework. As you say, high-fidelity interop can only be achieved with them by 1:1 feature matches between implementations exchanging documents. I.e., it is impossible to map markup in a document to functionality that does not exist in another application. As a practical matter, that will never occur because of the ongoing feature war.

But the technology for more featureful apps to round trip documents with less featureful apps is well understoood. There are different methods, but the method that involves no loss of information involves the use of profiles; that is, defined supersets and subsets of markup, coupled with the required setting of compatibility modes in implementing apps.

The W3C Compound Document Formats take this approach. The Compound Document by Reference Framework includes strict rules both for the creation of profiles and for processing of profiled markup. You can get a very good start on understanding the methodology by contemplating this single sentence from the Framework's conformance section:

A conformant user agent of a superset profile specification must process subset profile content as if it were the superset profile content.

But ODF and OOXML eschew such well understood methodology for achieving interoperability despite feature mismatches, in violation of JTC 1 Directives. They specify no interoperability framework and neither have been profiled. Moreover, there are only two plausible explanations for their not doing so: either ignorance or a desire to ensure that the most featureful and widely adopted implementations of each, OOo and MS Office, remain the leaders of their respective markets by enabling only one-way "interoperability" with those applications.

You also labor under a misconception in arguing that ODF is incapable of expressing the full range of functionality in MS Office. It requires extensions, yes. However, OOo itself uses some 150 custom extensions. But the da Vinci ODF plug-ins for Microsoft Office proved that only five generic extensions were necessary to do so. And the fidelity in converting from ODF to the binary formats in MS Office was virtually flawless.

The interop problems encountered by the da Vinci development team were mostly going in the other direction. The principle barrier is that the OOo page layout engines, as reflected in the ODF specification, have a far richer vocabulary than Microsoft Office. That is not surprising since the exceedingly brittle Microsoft apps still use their original 16-bit page layout engines but StarOffice was designed from the git-go as a 32-bit app that takes far more advantage of the greater processing power.

The second major barrier they encountered was that OOo destroys extensions created by other conformant ODF implementations. Between the more limited functionality of MS Office and the OOo destruction of the needed extensions, the da Vinci team was unable to establish interop between MS Office and OOo. But there was no problem with expressing the full range of MS Office functionality in ODF.

But in standards work, we should not be overly concerned with expressing the full range of functionality of a given application. We are concerned with identifying a standard abstraction for the exchange of data between different information technology systems. Unfo

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