Figure 10-16 Viewing multiple calendars with OWA. in Visual C#.NET

Creation QR Code in Visual C#.NET Figure 10-16 Viewing multiple calendars with OWA.

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Exchange 2010 SP1 introduces the ability to share or publish calendars to the Internet. This feature is intended to allow Exchange to offer the same facility that exists in other Web-based calendaring software such as Google Calendar and Yahoo! Calendar.

The feature leverages the work done to introduce federated calendar sharing between Exchange organizations while understanding that the intended target is quite different. Calendar sharing depends on a high level of trust between the participating organizations, whereas sharing calendars with Internet users is obviously a much looser arrangement, because no one manages the Internet and there s no notion of credentials being required to look at calendar data that a user has decided to publish. On the other hand, the Internet does encourage the development and implementation of standard protocols that can be used to share data, and in this case the protocol is iCal, or iCalendar. Even though Exchange users can now share their calendars with Internet users, the operative word is can. Sharing does not happen automatically. Exchange 2010 SP1 does not suddenly tear down the shutters and publish every user calendar as widely as possible. Instead, administrators and users alike must both take deliberate and planned actions to first create the conditions where calendar sharing is possible and then to make the decisions about with whom to share calendar data and what level of transparency or access to support. The basis for calendar sharing is a vdir called /calendar that is underneath the /owavdir. To allow open sharing with the widest possible set of clients, the calendar vdir supports HTTP access. HTTPS connections will not be rejected, but HTTP is all that you need to share a calendar with an Exchange user.

The calendar vdir is serviced by a separate application pool to isolate it from OWA operations, so the fact that HTTP access is supported should not be a concern because there s no way for hackers to break into OWA just because they can get to a user s calendar .

By default, Exchange 2010 does not allow calendar sharing, and the administrator must configure Exchange before users are allowed to share calendars. The following steps must be taken:

containing the calendars that will be shared with Internet users must be populated with the name of the CAS server in the Internet-facing site through which connections will be channelled. For example:

Set-ExchangeServer Identity 'ExServer1' InternetWebProxy 'http://ExCASInternet.contoso.com'

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set to $True:

Set-OWAVirtualDirectory Identity "ExServer1\owa (default web site)" CalendarPublishingEnabled $True

can do this by amending the default sharing policy, or you can create a new sharing policy and apply that policy to the select group of mailboxes that you want to allow to share calendars. In this example, we set the default sharing policy to allow users to share calendar data at the level of free and busy information plus detail (the body of the appointment item) about appointments.

Set-SharingPolicy Identity 'Default Sharing Policy' Domains "Anonymous: CalendarSharingFreeBusyDetail"

Attendee lists or attachments are never shared for meetings . Sharing policies are discussed in more detail in 5, Exchange Management Console and C ontrol Panel .

If you create a new sharing policy, you will have to apply it to mailboxes using the Set-Mailbox cmdlet. For example:

Set-Mailbox Identity 'Redmond, Tony' SharingPolicy 'Internet Calendar Sharing Policy'

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Once the administrator has configured Exchange to allow calendar sharing to the Internet, users can publish calendars using the Publish This Calendar option available in the OWA calendar. Outlook doesn t support the same publishing feature directly, so when a user shares his calendar with an Internet correspondent through Outlook, he is redirected to the Web sharing page to execute the option. Figure 10-17 shows the publication process to make calendars available to Internet users. On the left, the user selects the Publish This Calendar option. This causes OWA to display the dialog box shown in the middle to collect details about how the calendar should be published. The user controls:

How much detail is revealed about appointments (the options are Availability Only, Limited Details, or Full Details). OWA will flag a warning if the user selects an option that is not allowed by the sharing policy that applies to the user s mailbox. How much calendar data are published. You can select to publish anything from one year to one day in advance of and before today.