What happens behind the scenes when synchronizing free/busy data between multiple Exchange organizations using GALsync?
When synchronizing different mail organizations GALsync reads the free/busy information of selected user objects in source and stores them in target as free/busy information related to the synchronized contact object.
GALsync does not sync free/busy every time it is modified in source. You might want to export free/busy times in a time window of minimal 5 minutes.
GALsync requires that in each Exchange messaging organization free/busy data are stored in system public folders too. If you use Exchange 2007 or Exchange 2010 you must have also a public folder store!
Furtheron you must realize that not only mailbox-enabled users can have free/busy information – mail-enabled contacts may have them as well. Even if a contact can not use Outlook and does not have a mailbox, you might store free/busy information depending on this object programmatically. With Outlook client you can read these information by composing an invitation.
Up to Exchange version 2003 all free/busy data solely have been stored in a system public folder called Schedule++ Free/Busy.
For each user/contact there is a special *.eml-file containing her free/busy data (see in subject column below).
Up from Exchange 2007 free/busy data does not have to be stored in public folders; via the availability service clients access the target mailbox’s free/busy data directly from the calendar. But this technology is not be used if you need to publish the free/busy data of contacts in a cross-org sync between mixed Exchange versions.
see Paul Robichaux Blog: Creating a public folder store for Exchange 2007 free/busy or
Technet Articel At Least One Exchange 2007 Public Folder Store is Required
Configuring GALsync with free/busy the policy will take the information of all selected users, groups and contacts and send these information to the target directory. In the target directory GALsync initially creates contact objects by using the transferred information. Also GALsync takes the transmitted *.eml-file of a source user and saves it to the appropriate public folder Schedule++. The file is associated with the targets contact object which represents the user of the source forest.
Conclusion: if you synchronize free/busy information with GALsync you need to have public folder stores in all mail organizations. All free/busy information are read from and stored into system public folder schedule++ – regardless the Exchange version you use.
|client||source organization||target organization||result|
|Outlook 2003||Exchange 2000/2003||Exchange 2000/2003||free/busy of contacts are present|
|Outlook 2007||Exchange 2000/2003||Exchange 2000/2003||free/busy of contacts are present|
|Outlook Web Access||Exchange 2000/2003||Exchange 2000/2003||free/busy of contacts are present|
|Outlook 2003||Exchange 2000/2003||Exchange 2007/2010||free/busy of contacts are present|
|Outlook 2007||Exchange 2000/2003||Exchange 2007/2010||free/busy of contacts are present **|
|Outlook Web Access||Exchange 2000/2003||Exchange 2007/2010||free/busy of contacts are present|
|Outlook 2003||Exchange 2007/2010||Exchange 2007/2010||free/busy of contacts are present|
|Outlook 2007||Exchange 2007/2010||Exchange 2007/2010||free/busy of contacts are present **|
|Outlook Web Access||Exchange 2007/2010||Exchange 2007/2010||free/busy of contacts are present|
|Outlook 2003||Exchange 2007/2010||Exchange 2000/2003||free/busy of contacts are present|
|Outlook 2007||Exchange 2007/2010||Exchange 2000/2003||free/busy of contacts are present|
|Outlook Web Access||Exchange 2007/2010||Exchange 2000/2003||free/busy of contacts are present|
Specials: because Outlook 2007 and higher contacts Availability web service for free/busy lookups – and Availability service looks directly into users calendar, it is not possible to get free/busy information from public folders. So you have to force Outlook 2007 clients not to use Availability service. This you can do by:
- add a dword “UseLegacyFB” with value 1
see Technet-article: Distributing Registry Changes
There are some other workarounds. See description in blog “GALsync, Free/Busy, Exchange 2010, Outlook 2010 and Public Folders”
Free/busy information is stored by default for 2 months / current month and next one). This is a behaviour configured at client side.
You synchronized the user object Anne from Exchange organization Source to Exchange Organization Target. Anne now is represented in Target as contact object.
Note: Source is Exchange 2003 based, Target is Exchange 2007 based.
You also synchronized Anne’s free/busy information.
If target forest’s Outlook 2007 user Pete wants to invite user Anne, her directory information is present in Pete’s Outlook (looking at the Global Address List). If Pete wants to do a meeting invitation the free/busy information of Anne are available and represented by the contact object of Anne in Target.
A disadvantage of this architecture may be that all information have to be physically present at target – requiring a little bit of storage. The source object is represented physically as contact object in target, the free/busy information is copied from source to the target. Compared with this: new architectures like Availability Webservices in Exchange 2007 and 2010 do not require the presence of objects in the other forest. But the new architectures do not offer free/busy access in all topologies with mixed environments. Additionally the require a functional Internet access with certificates.
GALsync is the real solution if
- free/busy information must be available even if internet connection is broken
- publication of webservices over internet are not possible or allowed by your company
- you have a mix of Exchange versions
There are several synchronization methods using Availability WebService up from Exchange 2007 – but a lot of synchronization scenarios are in mixed environments using Exchange 2000, 2003, 2007 and 2010.
Even most companies use Outlook 2003 (not able to contact Availability Webservice in Exchange 2007).
So it is quite a good solution to install a public folder root and to distribute free/busy information “by classical technique”.
- A lookup, under which cirumstances you do not need a 3rd-party tool for Free/Busy sync is provided in our blog Configuring Free Busy information between Exchange organizations.
- A rough comparision of NETsec GALsync and ILM 2007 is provided here.