Managing Exchange Invites in Apple’s iCal

Uncategorized Feb 19, 2008

For better or worse, most of my coworkers live and die by their Exchange calendars. Unfortunately, as a developer working on a Mac 24/7, there aren’t many options for dealing with the barrage of Outlook invites I receive each day. I can either use Entourage which only kinda-sorta-works, or I can just deal with it and transcribe each invite manually into iCal or Google calendar. Both options are crap. (Groupcal from Snerdware used to be an option, but it doesn’t support Leopard and their developers appear to have stopped work on the product.) There’s no reason OS X shouldn’t be a full-fledged citizen in an Exchange environment. But, until that happens, here’s a collection of ever-improving AppleScript and PHP hacks I’ve written to make life in an Exchange world a little bit better

There are three problems we need to solve

  1. Viewing a user’s free/busy calendar
  2. Easily adding Exchange invites to iCal
  3. And accepting or declining those invites

My solution is a set of four Applescripts and a PHP script that (for me at least) make this nearly seamless. The bulk of the code is a PHP class called OWA which interacts with Outlook Web Access – a prerequisite for all of this working. Nearly all organizations which run Exchange have this enabled, so it shouldn’t be a problem for most people. The Applescripts are primarily just glue which pull information from Mail and pipe it into the PHP script for processing.

1. Viewing a User’s Free / Busy Schedule in iCal

I’ve placed the OWA PHP script in my Mac’s local web root. To subscribe to a user’s free / busy calendar I choose Subscribe from iCal’s Calendar menu and use the following URL:


Where <username> is someone’s Exchange username. Behind the scenes, the PHP script logs into Outlook Web Access and scrapes the user’s calendar info and returns it as a properly formatted iCalendar file which iCal loads.

I’m the first to admit that this isn’t the most user-friendly solution, but it works. I stay subscribed to my manager and nearby coworkers’ schedules since they’re who I typically schedule meetings with. If I need to see someone more exotic, I just create a new calendar for them temporarily and delete it when I’m done.

2. Easily adding Exchange invites to iCal

To move Exchange invites from Mail into iCal, I use this AppleScript. Warning: I’m hardly an AppleScript expert, so suggestions are very much welcome.

tell application "Mail"
    set theSelectedMessages to selection
    repeat with theMessage in theSelectedMessages
        set theAttachment to first item of theMessage's mail attachments
        set theAttachmentFileName to "Macintosh HD:tmp:" & (theMessage's id as string) & ".ics"
        save theAttachment in theAttachmentFileName
        do shell script "fn='/tmp/$RANDOM.ics';cat " & quoted form of POSIX path of theAttachmentFileName & "| grep -v METHOD:REQUEST > $fn;open $fn; rm " & quoted form of POSIX path of theAttachmentFileName & "; exit 0;"
    end repeat
end tell

In a nutshell, that grabs the first attachment from the currently selected Mail message (I blindly assume it’s an invite attachment), removes the line that prevents iCal from editing the event, and tells iCal to open it. At that point iCal takes over and asks you which calendar to add the event to.

It’s important to note that while the event is now stored in your local iCal calendar, it has not been marked as accepted or declined in your Exchange calendar. You need to specifically take that action using one of the next scripts.

3. Accepting or Declining Exchange Invites in Mail

To accept or decline an event (or even mark it as tentative) I’ve provided three scripts called “Accept Invite”, “Decline Invite”, etc. that pass the event to the OWA PHP script which then marks the event as such in your public calendar. Here’s the “Accept Invite” AppleScript. The other two are basically identical.

tell application “Mail” set theSelectedMessages to selection repeat with theMessage in theSelectedMessages set theSource to content of theMessage set theFileName to “Macintosh HD:tmp:” & (theMessage’s id as string) & “.msg” set theFile to open for access file theFileName with write permission write theSource to theFile starting at eof # close access theFile do shell script “curl http://localhost/owa.php?accept=” & POSIX path of theFileName end repeat end tell

Again, I make no claims about the quality of my AppleScript – I just know that this works well enough to get the job done.

Closing Notes

And there you have it. To sum up:

  1. Download my scripts
  2. Place owa.php into your local web root
  3. Place the four Applescripts into ~/Library/Scripts/Applications/Mail

After that, it’s up to you to call those AppleScripts as needed. I use Red Sweater Software’s Fast Scripts application to assign keyboard shortcuts to them. You could also use Quicksilver or whatever method works best for you.

Like I sad above, these scripts are constantly in flux as I revise and improve them. I’ll post any significant updates to this blog – and I hope you’ll email me with any questions you have or improvements you make.