Interoperability is an important part of the Chandler Project vision.

Chandler is about trying to match the way people really work. And everyone uses lots of tools to get their job done. One of the first things people want to know when considering trying out Chandler software is “Will it work with what I already use? Can I switch back if I don’t like it? Will it work with the tools that friends of mine use?”

We believe the answer to all these questions is “YES”! You can safely and productively start using one or more of the Chandler Project components on top of your existing toolset. Go ahead, try it out! Read more below to learn the details.

For a bullet-list summary of our best-available notes on specific applications and which features are supported with each, see our interop overview.

Import/export

The gold standard of calendar transfer is the “ICS” file (in iCalendar format). Most calendar and task list applications support both import and export of ICS files.

You can try out Chandler Desktop without switching from your current setup. Just export one or more ICS files from your current application, then import those files into Chandler Desktop (continuing to use your current app). To switch over permanently, just export+import again a final time!

If you later decide you’d like to change again, you can export ICS files from Chandler Desktop or Chandler Hub, using those files for import into a wide variety of applications.

We’ve seen import and export work for Outlook 2003/2007, Mozilla Lightning/Sunbird, Apple iCal, and others; it should work with a great many apps, probably yours included.

Note that Outlook doesn’t export full information by default; we’ve found this $10 application from littlemachines produces high-quality exports from Outlook that work well with Chandler Desktop.

In practice, doing ICS import/export can have gotachas. Not all application combinations/roundtrips are 100% perfect. We urge you to keep backups and try out import/export before committing your important data to any application. In Chandler Desktop, we’ve spent a lot of time tuning our import/export routines to handle as many variants and details as we can. Chandler Desktop properly handles events, tasks, timezones, recurrence, and other details. Please report any import/export problems you encounter.

We’ve put together some additional information about import/export with Chandler Desktop specifically, so check that for additional hints and notes.

Synchronization

ICS import/export is great for transferring your data between apps, but it’s a manual process not suited to keeping multiple applications in sync. Usually when you import a data set, your app will overwrite changes you may have in your local copies of those events. It’s hard to make changes in two separate apps.

Chandler Desktop and Chandler Hub both support multiple network sync protocols. Where other applications (Outlook, iCal, etc) overlap at least one of these protocols, interoperability is possible on at least some level.

One main idea to keep in mind when thinking about these various systems is whether a scheme is “read-only” or “read-write” (ie, bidirectional). It seems like read-only (or 1-way) interoperability works more reliably today, but protocols like CalDAV promise a new era of real-time, 2-way synchronization of calendar data between lots of free and for-pay applications and web services.

The big news is that you can do 2-way/read-write calendar and task synchronization today, both privately and shared with other people. Here’s a list of the main ways to do that, based on Chandler Project software.

Webcal, 1-way sync

The most simple network protocol is to take an ICS file (see above in import/export) and post it to the web, so various apps can download it (redownloading to check for changes periodically). This system is called webcal.

Chandler Desktop works great for subscribing to a number of public webcal URLs and overlaying them all on one canvas. This is a great way to keep track of lots of calendars.

If you store any events/tasks on Chandler Hub, then you can login to get a URL that you can enter into the right spot in Outlook, Apple iCal, Google Calendar, Lightning/Sunbird, Evolution, Zimbra, and many other apps to synchronize that Hub calendar with your app. This is always a read-only/1-way procedure.

Using webcal, in Outlook 2007, you can overlay say personal or family Hub calendars on top of your Exchange/Outlook calendars you use at work. (Look for “Internet Calendar” features in Outlook’s help.) If you make a change on the Hub or Chandler Desktop and then synchronize, you’ll see that change in your work Outlook’s display.

You can also subscribe to Hub calendars in Outlook 2003, but only view the calendars side-by-side. Other apps like iCal, Lightning/Sunbird, Google Calendar, and Evolution all support overlaying the Hub calendar with other calendars.

Many applications, Outlook included, can also publish a webcal calendar to a web server. You can use Chandler Hub as a destination server for most of these webcal-publishing apps. This works, but please note this does not provide a web UI for that calendar, and it’s again a 1-way publication. The original application will very likely not detect any changes made to this webcal file on the server.

Webcal, 2-way sync

Chandler Desktop can also do 2-way synchronization via webcal. Most applications treat a webcal file as read-only or write-only, but Chandler Desktop will check for changes in a webcal file it is monitoring and integrate those changes. If used with another application that also checks for changes, you get 2-way synchronization. We know Lightning/Sunbird does this (though you might chose to use CalDAV to synchronize instead).

CalDAV, 2-way sync

CalDAV is an emerging standard protocol for open calendar exchange. It’s not a protocol that’s used directly between two clients (like ICS files are), but rather defines a calendar server to which multiple clients can subscribe and synchronize. Chandler Hub also provides a read-write web UI to any calendar you store or use in your account.

The Open Source Applications Foundation via the Chandler Project was an early supporter of CalDAV. Together, our Chandler Desktop application and Chandler Server server product are some of the oldest and most mature implementations of the CalDAV standard and we plan to continue that support.

Chandler Hub is, as far as we know, essentially the leading free CalDAV service offered to the public. Given a fully-cooperating CalDAV client (Lightning/Sunbird, iCal 3.x, and Evolution all cooperate to various degrees), you can use these other clients regularly or occassionally and even use Chandler Desktop for advanced work (like sharing a single item between multiple calendars).

Chandler Desktop can subscribe to and publish a collection (calendar+events) to any CalDAV server (Apple Calendar Server, RSCDS, Bedework), or actually any WebDAV server (Apache mod_dav, .Mac, etc). Both of these mechanisms support bidirectional (read-write) synchronization, so multiple applications or people can all create, edit, and delete events and tasks any time they want, using the application of their choice.

iCal 3 (in Apple 10.5 “Leopard”) is a great new CalDAV-using PIM client. You can use it to make changes to your Hub collection, and still be able to use the Hub web UI to make changes from anywhere. Note that iCal 3 supports read-write calendars only to calendars in your account. Chandler Desktop and Chandler Hub let you subscribe to shared collections owned by other users with full read-write access.

Email integration

Chandler Desktop is not a complete email client; it is rather intended to complement your existing email client. The mechanism we use is to create dedicated Chandler folders on your IMAP server. Using your regular email client (Outlook, Thunderbird, Mail.app, Evolution, etc), you just drag an email from your inbox into a Chandler folder, where the message will be parsed for event, task, and other information.

You should also be able to send email update of items from Chandler Desktop using just about any outgoing mail server available. Events emailed this way appear as ICS attachments. We’ve tested Exchange, Postfix, Gmail, Yahoo mail, and Hotmail/MSN among others.