Synchronizing IPhoto libraries between two Macs

After spending some time finding a working solutions on how to sync the IPhoto libraries on two computers I gave up and decided to implement my own.

Intro
The solution is based on a server where the clients can sync their images to. This solves the problem with one client trying to sync when the other client is offline. It should be possible to get this running without a server but I have not tried it. The clients are running Leopard and the server is a Via Epia mini-itx running Ubuntu Linux (on the server any OS which is able to act as SSH and rsync server will be fine).

How is it working
The clients will sync their image directories with a directory on the server using rsync. First it executes rsync to receive all changes from the server directory and then it executes rsync to upload all the added images on the client to the server. After this syncing of files is completed a Java application is executed which scans the IPhoto library and the image directory on the client. Pictures which has not already been imported to IPhoto will then be imported using Applescript. All the executed scripts and applications are executed automatically hourly on the clients.

Limitations

• Only the original files on the clients are syncronized between the clients. This means that any change in IPhoto (e.g. edit image, delete image, rename image..) wont be synchronized.
  
• If multiple clients are syncing with the server at the same time there is a risk that only a part of a directory with images will be imported. Next time it will be imported again, a new "roll" with the same name will be created and the remaining images will be imported. IPhoto will ask if the already imported images should be imported again.
• The image directories may not have any other files than files that can be imported into IPhoto. It will result in errors when importing.
• A drawback of this solution compared to accessing the images on the server is that the images potentially uses a lot of harddrive space. But then again it is safer to store the images multiple places, the performance is better when working with the images (espcially if the clients are on a wireless network) and the images are accessible also when the clients aren't on the same network as the server.
• The Java application used for accessing IPhoto relies on Apple not changing the format of the AlbumData.xml file which is a database that keeps track on what is imported and what rolls and albums are created. As a side note you should know that the application uses XPath to read from the file but never writes to it as that could harm data in IPhoto. All writes to IPhoto is done through Applescript.
• It does not deal well with duplicate images. It will work but every time IPhoto discovers a duplicate it will prompt the user if the duplicate should be imported or ignored. The shell application fdupes can be used to remove duplicate files (on ubuntu just run sudo apt-get install fdupes to install it).
• Photo Booth images will be synchronized and imported but as Photo Booth is using an unconfigurable naming scheme the clients will most likely overwrite each others files. Photo Booth syncing can be turned off by excluding it in the rsync calls in /scripts/syncIPhoto.sh

Installation guideline

1. On the server create a user for each client that should be synced (eg. user1 and user2)
   
2. Create a directory on the server (eg. /data/pictures/sync). The directory should be put in a group that is accessible for all users created in step 1.
   
3. Setup passwordless ssh between the clients and the server (see past article)
4. Copy the iphotosync application directory to /Applications/ on all the clients
5. On the clients edit the first section (e.g. username and server ip) of the shell script /Applications/synciphoto/scripts/syncIPhoto.sh
6. On the clients edit the username in the plist-file /Applications/synciphoto/launchd/com.skyandyou.tools.iphoto.sync.plist
7. Copy or move the com.skyandyou.tools.iphoto.sync.plist file to /Users/username/Library/LaunchAgents
8. On the clients add the plist to launchd by executing the following command from Terminal (this will make the synchronization run every hour):
   launchctl load /Users/username/Library/LaunchAgents/com.skyandyou.tools.iphoto.sync.plist
   
9. On the clients change the IPhoto settings so images wont be copied to the IPhoto-library (IPhoto/Preferences/Advanced)
   
10. Test the synchronization on the client by executing this command in Terminal:
    launchctl start com.skyandyou.tools.iphoto.sync
    Open an other Terminal and watch all the action in the system.log:
    tail -f /var/log/system.log

Relevant Links
launchd
launchctl
rsync
fdupes
launchd information
rsync FAQ