Outlook's Handling of Recurring Appointments

Question

I wanted to say that while perusing the object model for Microsoft Outlook and playing with some of the concepts, I came across the GetRecurrencePattern function. I was very surprised and impressed to find out how Outlook handles the Recurring Appointment Model. From what I can tell, the software will create one physical appointment item and then generate the calendar view with recurrences based on that one item. This is pretty sweet and definitely much more simple than trying to store an item for each recurring appointment.

 I have one question about how Outlook handles this though. Is the only physical object stored the olApptMaster item? If so, is the only way that one can ever get an olApptOccurrence by accessing the Selection object? What if you for some reason wanted to calculate if a user was going to have an appointment on a certain day and time? How could you calculate the recurrence pattern to find out if there will be a conflict?

Anyway, good stuff and rather exciting. :)

Thank you,
 Preston

Answer 1

You get an occurrence by calling GetOccurrence(). You are responsible for calculating the date/time of whatever recurrence you want, using the pattern for the calculation. You also have to check the Exceptions collection for deleted instances and exceptions. You do that if GetOccurrence() fails.

 

The origins of the recurrence pattern dates back to the beginnings of MAPI, and the old predecessor to Exchange, Microsoft Mail. That's why backwards compatibility makes it so difficult to update the pattern or add more flexibility, the pattern is calculated on the fly for various recurrence patterns and is different depending on the recurrence used.

 

The reverse engineering of the binary of the recurrence pattern is fascinating.

--
Ken Slovak
[MVP - Outlook]
http://www.slovaktech.com
Author: Professional Programming Outlook 2007.
Reminder Manager, Extended Reminders, Attachment Options.
http://www.slovaktech.com/products.htm

 

 

"Preston001" <=?utf-8?B?UHJlc3RvbjAwMQ==?=> wrote in message news:7cf53a74-9d84-4749-8c2b-e6c43e34efb5...

I wanted to say that while perusing the object model for Microsoft Outlook and playing with some of the concepts, I came across the GetRecurrencePattern function. I was very surprised and impressed to find out how Outlook handles the Recurring Appointment Model. From what I can tell, the software will create one physical appointment item and then generate the calendar view with recurrences based on that one item. This is pretty sweet and definitely much more simple than trying to store an item for each recurring appointment.

 I have one question about how Outlook handles this though. Is the only physical object stored the olApptMaster item? If so, is the only way that one can ever get an olApptOccurrence by accessing the Selection object? What if you for some reason wanted to calculate if a user was going to have an appointment on a certain day and time? How could you calculate the recurrence pattern to find out if there will be a conflict?

Anyway, good stuff and rather exciting. :)

Thank you,
 Preston

---

Ken Slovak MVP - Outlook

Answer 2

If the reassurances were physical and not virtual, you'd have a ____ of a mess on your hands, let alone that it'd eat up a ton of storage. One reoccurring item wouldn't be a problem but what if you're dealing with an organization of several hundred people and numerous items that reoccur on a weekly basis or daily basis? Not to mention that from a practical standpoint the probability of a reoccurring being different from the rest is actually quite slim.

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David H