PIM Action 2 WTC - context and references to xCal recurrences

[William Cox <wtcox@CoxSoftwareArchitects.com>]

Action 2 was examining how and whether the XCAL structures for Rdate etc should apply to PIM.

PIM CSD04 uses string values for rdate, exdate, and rrules, following RFC 5545. Multiplicity internal to the single string value is as defined in 5545, so the values are identical.

RFC 6321 (xCal) takes the recurrence properties RRULE, RDATE, EXDATE (see 3.8.5.1, .2, .3 RFC5545) and structures them.  This is IMO an improvement on the 5545 approach, and should be followed in the PIM.

It is not followed in PIM CSPRD04.

If it were followed, the arguments about overloading dtStart and so forth between recurrences and a simple interval would be moot. Also, it would be much more clear that recurrences are optional, and a PSM with no recurrences would be easier to define ("don't use the Recurrence component" versus "don't use rdate, exdate, and rrules").

The 6321 does not include the XSD, which is in ws-calendar so far as I can see; the appropriate schema to consider is iCalendar-props.xsd : That schema has (line 652ff)

  <!-- 3.8.5 Recurrence Component Properties -->
  <!-- 3.8.5.1 Exception Date/Times -->
  <xs:complexType name="ExdatePropType">
    <xs:complexContent mixed="false">
      <xs:extension base="xcal:DateDatetimePropertyType"/>
    </xs:complexContent>
  </xs:complexType>
    
  <!-- 3.8.5.2 Recurrence Date/Times -->
  <xs:complexType name="RdatePropType">
    <xs:complexContent mixed="false">
      <xs:extension base="xcal:DateDatetimePropertyType"/>
    </xs:complexContent>
  </xs:complexType>
    
  <!-- 3.8.5.3 Recurrence Rule -->
  <xs:complexType name="RrulePropType">
    <xs:complexContent mixed="false">
      <xs:extension base="xcal:RecurPropertyType"/>
    </xs:complexContent>
  </xs:complexType>
    
  <!-- x.x.x.x Deprecated ExRule -->
  <xs:complexType name="ExrulePropType">
    <xs:complexContent mixed="false">
      <xs:extension base="xcal:RecurPropertyType"/>
    </xs:complexContent>
  </xs:complexType>

Exrule is deprecated in 5545, so we won't consider that.

There are two auxilliary types: DateDatetimePropertyType is

  <!-- Properties that take a date or date-time value -->
  <xs:complexType name="DateDatetimePropertyType" >
    <xs:complexContent mixed="false">
      <xs:extension base="xcal:BasePropertyType">
        <xs:sequence>
          <xs:choice>
            <xs:element ref="xcal:date-time"/>
            <xs:element ref="xcal:date"/>
          </xs:choice>
        </xs:sequence>
      </xs:extension>
    </xs:complexContent>
  </xs:complexType>

and RecurPropertyType is

  <!-- Properties that take a recurrence value -->
  <xs:complexType name="RecurPropertyType" >
    <xs:complexContent mixed="false">
      <xs:extension base="xcal:BasePropertyType">
        <xs:sequence>
          <xs:element name="recur" type="xcal:RecurType"/>
        </xs:sequence>
      </xs:extension>
    </xs:complexContent>
  </xs:complexType>

My next email will suggest how I think the PIM UML model should address these, and how to make restricting recurrences emore clear for PSMs.

Thanks!

bill

--

William Cox 

Email: wtcox@CoxSoftwareArchitects.com 

Web: http://www.CoxSoftwareArchitects.com 

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