Tuesday, September 12, 2017

Using the Office365/Exchange 2016 REST API Calendaring

When it comes to Messaging API's there no more complex thing then calendaring, not only because most vendors implement things a little differently but Exchange also has a little legacy feature drag because of its length of time in the market place and the difficulties in changing the technology and human interaction with it. The new REST API offers yet another window into calendaring on Office 365 and Exchange 2016 with a major security benefit over its predecessor which is the ability to be able to scope your application access so it can only access the Calendar folders in a Mailbox where previously apps may have needed to have Full Rights or impersonation rights on a Calendar. Also the new REST API allows you to interact with Group Calendars (or Teams Calendar) so leveraging the new REST API to value add to the adoption of these new features can be a worth your while.

To Support Calendaring I've added 2 new cmdlets to the Exch-Rest module to handle creating Appointments and Meeting and a few other supporting cmdlets to create the data structures necessary to handle each of the data types. I have a full documentation page with examples on GitHub here https://github.com/gscales/Exch-Rest/blob/master/Samples/CalendaringExamples.md

Calendaring Types

As I mentioned in my opening there is no more complex a thing then calendaring so lets look briefly at the converge I've added so far in the Module

Creating a Single Appointment in the default Calendar

Fairly basic thing to do you use the New-CalendarEventRest cmdlet to specify all the properties you want to set in this New Appointment

New-CalendarEventREST -MailboxName mailbox@datarumble.com -AcessToken $AccessToken -Start ([DateTime]::Parse("2017-07-05 13:00")) -End ([DateTime]::Parse("2017-07-05 14:00")) -Subject "Name of Event"

Creating a Single Appointment in the secondary Calendar

The new REST API allows you to enumerate all the calendars in a Mailbox and returns them as a flat list structure (rather then a parent/child like Mailboxes). To cater for creating appointments on Secondary Calendar's (eg any calendar other then the default) I included a -CalendarName parameter which first finds the secondary calendar using a filter based on the DisplayName and then allows you to create the appointment like in the first example eg

New-CalendarEventREST -MailboxName mailbox@datarumble.com -AcessToken $AccessToken -Start ([DateTime]::Parse("2017-07-05 13:00")) -End ([DateTime]::Parse("2017-07-05 14:00")) -Subject "Name of Event" -CalendarName 'Secondary calendar'
Creating a Single Appointment on a Group Calendar

To create an Event on a Group (or Teams) Calendar the user your using to access the REST API must be a member of that group in question and have the necessary rights on that Calendar. To cater for the necessary changes to the REST Uri you need to post to for groups which involves first finding the GroupId of the Group you want to access, I've added a -Group switch and -GroupName parameter to the cmdlets. The cmdlets then will use a lookup of the group based on its displayname to find the GroupId first and then POST to the Group calendar. (The organizer of the appointment you create on the Group Calendar becomes the Mailbox your posting as). Eg

#Creates a new all event for the 5th of July from 13:00-14:00 on the a group calendar called 'Powershell Module'
New-CalendarEventREST -MailboxName mailbox@datarumble.com -AcessToken $AccessToken -Start ([DateTime]::Parse("2017-07-05 13:00")) -End ([DateTime]::Parse("2017-07-05 14:00")) -Subject "Name of Event" -group -groupname 'Powershell Module'
Creating a Recurring Appointment

Appointment or Meeting Recurrence is probably the hardest thing when it comes to Calendaring for developers and admin to understand because there are so many different permutations of recurrence (eg daily,weekly,yearly etc). Discussing this in detail would consume many pages and hours so  I have covered the basics on https://github.com/gscales/Exch-Rest/blob/master/Samples/CalendaringExamples.md an example of creating a recurring appointment looks like

$days = @()
$Recurrence = Get-Recurrence -PatternType weekly -PatternFirstDayOfWeek monday -PatternDaysOfWeek $days -PatternIndex first  -RangeType enddate -RangeStartDate ([DateTime]::Parse("2017-07-05 13:00")) -RangeEndDate ([DateTime]::Parse("2019-07-05 13:00"))
#Creates a new all day event for Today on the default calendar
New-CalendarEventREST -MailboxName mailbox@datarumble.com -AcessToken $AccessToken -Start ([DateTime]::Parse("2017-07-05 13:00")) -End ([DateTime]::Parse("2017-07-05 14:00")) -Subject "Monday Meeting" -Recurrence $Recurrence

A meeting from an API perspective is an appointment with Attendees, an Attendee can be Required, Optional or a Resource like a Meeting rooms. One of the things the REST API can't do which you can do in EWS is create Meetings with attendees and control whether Meeting invitations are sent or not (they will always be sent in REST). To help out with creation of the correct attendees structure I've included the New-Attendee cmdlet so it can be used like such to creating meetings with attendees

$Attendees = @()
$Attendees += (new-attendee -Name 'fred smith' -Address 'fred@datarumble.com' -type 'Required')
$Attendees += (new-attendee -Name 'barney jones' -Address 'barney@datarumble.com' -type 'Optional')

New-CalendarEventREST -MailboxName mailbox@datarumble.com -AcessToken $AccessToken -Start ([DateTime]::Parse("2017-07-05 13:00")) -End ([DateTime]::Parse("2017-07-05 14:00")) -Subject "Name of Event" -Attendees $Attendees
If there is anything missing or that you need to do but can't work out please post an issue https://github.com/gscales/Exch-Rest/issues on GitHub and I'll add a sample to demonstrate it.

Coming Soon

Coverage for Free/Busy

The module is available from the PowerShell Gallery https://www.powershellgallery.com/packages/Exch-Rest and the source from Github