oBIX 1.1 Issues

["Brian Frank" <bfrank@tridium.com>]

The following is a list of issues to discuss for oBIX 1.1 that I’ve run across:

 

1) Do we roll the XML namespace version?

 

2) Do we allow the use of floating abstime and times?  iCalendar allows times to “float” independent of a timezone – is this feature used?  If not commonly used, then I would recommend we disallow floating times – it causes a lot of confusion and implementation head-aches.  XML Schema technically allows it also, and the current oBIX specification is silent on the issue.

 

3) How do we integrate timezones?  XML Schema allows no offset (floating), UTC, or an explicit offset.  iCalendar disallows an explicit offset, but allows floating, UTC, and a tzid reference.  My initial thought is that oBIX requires UTC or explicit offset – but that we also allow the use of a tz facet to reference a timezone definition. Timezone probably becomes more of a core type like Unit, rather than specific to scheduling.

 

4) I think we add two new value types date and time.  Time will follow the abstime rules for timezone.  Literal representations will be based on XML Schema.

 

5) Do we need support for a binary value type?  iCalendar has it, however recommendation is that it should be referenced out of band via a URI – that is definitely the current oBIX model.  Unless we have a known use case, then I would recommend that binary data is required to be identified via a uri object type.

 

6) Looking at the oBIX specification, we defined the Weekday and Month enumerations with everything spelled out.  That doesn’t seem right to me, especially since most specifications use a three letter abbreviation.  iCalendar uses two letter abbreviations for weekdays.  Should we change?  It means breaking backward compatibility (although I seriously doubt anyone is using them yet).

 

7) iCalendar type system is a bit weird: properties, property types, and property parameters.  We will likely have to combine property types and property parameters to achieve a more natural type system using contracts.

 

8) Some properties can be included multiple times such as RELATED-TO and RRULE.  This is problematic if those properties are identified by name, because oBIX forbids duplicate child names.  So we have to a) specify those properties as a list or b) specify those properties as unnamed and identity them via their contract.

 

9) Do we need to support any component other than VEVENT?  Currently I’m thinking that we do not support the VJOURNAL, VTODO, VFREEBUSY, or VALARM components.