Client and Address Book Server Communication for Office Communications Server 2007 R2
The Address Book URL is the path that clients use to access the data files in the Address Book Server file store. This URL is stored on the Standard Edition server or Enterprise pool, and it is returned to the client when it logs on to its Standard Edition server or Enterprise pool.
Office Communicator can access the Address Book file store by using a URL in either of the following two formats:
- File URL (also called a UNC path) is required. The file URL is a standard file URL in the format \\server\share. Standard share and NTFS permissions are applicable to this URL.
- An HTTP or secure HTTP (HTTPS) URL is optional. An IIS HTTP server functions as an optional component of the Address Book Server. The IIS HTTP server is optional if all users will access the file store from within the intranet. However, if you want the information in the file store to be accessible by remote users who are connecting from outside the intranet or by users in a branch office or remote site, an IIS Server is required, and you must configure HTTPS (Basic over SSL) on your virtual directory.
Note
If your clients use an HTTPS URL to access the Address Book Server file store, verify that the client certificate is already trusted by Internet Explorer prior to an attempt by clients to access the Address Book URL. If the client certificate is not trusted, the download will fail. The user is not prompted to check the certificate and to configure it as trusted. Consider using a certificate that is trusted by default on your client.
The type of authentication required for an Address Book URL varies depending on whether the URL is used for internal or external clients. The following table shows the supported authentication for each type of URL.
Supported Authentication for Address Book URLs
| Address Book URL type | Authentication |
|---|---|
Internal |
Integrated Windows Authentication (NTLM or Kerberos) |
External |
NTLM or HTTPS (basic over SSL) |
Office Communicator accesses the available Address Book URL entries when it logs on to its Standard Edition server or Enterprise pool.
Address Book Client Provider
The Address Book Client Provider is a module within Office Communicator that is responsible for synchronizing GAL contacts with the Office Communicator contact database. Since all GAL contacts are read-only, this synchronization is a one-way process as follows:
- Office Communicator logs on to the Enterprise pool or Standard Edition server using its logon logic.
- From the pool or Standard Edition server, Office Communicator receives the Address Book URL. There can be one or more intranet (or internal) and one or more Internet (or external) URLs.
- Office Communicator determines if it is connecting from inside the intranet or connecting from outside through an Access Edge Server and then selects the appropriate URL for the connection.
The logon credentials of the Office Communicator client are used to connect to the selected Address Book Server URL. Office Communicator uses the standard Internet Explorer API to perform the URL authorization. If access is denied, one of the following occur:
- If the user is inside the intranet, the client displays an icon indicating an Address Book download failure. The user is not asked for credentials again.
- If the user is outside the intranet, the user is prompted to enter proper URL credentials.
Note
Office Communicator supports the use of a fallback URL for high availability. For details about configuring additional URL entries, see Using WMI to Configure Address Book Server Settings.
Client Download Process
If a client is accessing the URL for the first time, upon successful connection, the client attempts to download the current full data file. On subsequent days, the client attempts to download a delta file based on the last full synchronization date. Typically, this delta file is based on the previous day. If the client is offline for a day or more, it determines which delta files it must download to get up to date. If the client is offline for more than 30 days, it attempts to download the full data file.
Storing this information in a local database reduces the time taken to synchronize information on the client computer with the latest information stored in Active Directory, thereby significantly improving the GAL search process. The location of this database is <drive letter>: Documents and Settings\<user>\Local Settings\Application Data\Microsoft\Communicator.
In the event of a download failure because of network connectivity or other issues, the client retries in time intervals that double on each failure (1 minute, 2 minutes, 4 minutes, and so on, up to a maximum of 64 minutes). Any data that was downloaded before the failure is discarded, and the retry begins again at the beginning. If the failure persists for more than 24 hours, a warning appears, and an application event is added to the Event Log.
When the client logs in, it determines if it has been more than 24 hours since the last download. If so, then the current download occurs immediately. Otherwise, download is scheduled at 00:00 UTC (Universal Coordinated Time, also known as GMT).
Exceptions: If the address book contains over 50K contacts, the client maintains a separate “delta” database GalContactsDelta.db for GAL contacts, and periodically merges updates into its “main” database GalContacts.db. This helps reduce the processing required on a daily basis on the client machine in very large environments.
Internet Explorer Dependencies
Because Office Communicator uses the standard Internet Explorer API to perform the URL authorization, it depends on the following Internet Explorer settings:
- Security Settings, including the intranet URL settings. For example, if you are using an Internet (external) type of URL (for example, http://server.com/share) for intranet (internal) users instead of an intranet URL (for example, https://server/share), Office Communicator ignores this entry unless this URL is configured explicitly as an intranet URL in Internet Explorer. We recommend that you use an intranet URL for internal users. If you have a specific need to use an Internet URL, you must manually configure this URL as an intranet URL in Internet Explorer, or you must use Active Directory group policy to configure the URL.
- Proxy Settings. If you use an HTTP proxy to manage your Web traffic and the Address Book data flows through this proxy, then the client will not be able to access these URLs if the proxy becomes unavailable or if authorization problems occur with the proxy.