What is the first instance of a recurring event if the start date time is before the instance matched the recurrence rule?

2 posts, 0 answers
  1. Jason
    Jason avatar
    9 posts
    Member since:
    Oct 2015

    Posted 07 Mar Link to this post

    Hi Admin,

    We have a particular case which is creating a recurring event with the rule of repeating 3 times every Tuesday Weekly starting from 14/3/2016 13:00 to 13:30 as below:
    Start Time: 2016-03-14 13:00:00.000
    End Time: 2016-03-14 13:30:00.000
    Recurrency Rule: FREQ=WEEKLY;COUNT=3;BYDAY=TU

    Regarding to the rfc5545 icalendar spec (3.8.5.3.  Recurrence Rule) in which Kendo UI Scheduler follows, it specifies that:
    The recurrence set is generated by considering the initial "DTSTART" property along with the "RRULE", "RDATE", and "EXDATE" properties contained within the recurring component;
    The "DTSTART" property defines the first instance in the recurrence set; 
    The "DTSTART" property value SHOULD be synchronized with the recurrence rule, if specified;  
    The final recurrence set is generated by gathering all of the start DATE-TIME values generated by any of the specified "RRULE" and "RDATE" properties, and then excluding any start DATE-TIME values specified by "EXDATE" properties.  

    Therefor,  it should generate 3 instances including Mon 14/03/2016, Tue 15/03/2016 and Tue 22/03/2016 (*). However, the Kendo UI demo with this sample gave 3 instances which are Tue 15/03/2016, Tue 22/03/2016 and Tue 29/03/2016.

    Could you please advise how we can configure Kendo UI to have the result as (*)

    Thanks so much for your help.

  2. Georgi Krustev
    Admin
    Georgi Krustev avatar
    3707 posts

    Posted 10 Mar Link to this post

    Hello Jason,

    Indeed, the recurring engine of the Scheduler follows the RFC5545 specification, but also the specification is something that tend to be interpreted differently (as every person understands the rule a bit differently). That is why we compared and aligned our behavior with the de-facto standard in recurring calendars - MS Outlook and Google Calendar. Their engines does not create events in Monday if the same recurring rule is used. Here is a screencast that demonstrates that:
    The Google Calendar behaves the same way.

    I am afraid that the current behavior cannot be changed and you will need to consider different rule to accomplish your goal. As far as I know, you most probably will resort with two events one for Monday and second one for the recurrence series.

    Regards,
    Georgi Krustev
    Telerik
     
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