5. Availability Service
The
Availability service is the name of the service that provides free/busy
information to Outlook 2007 clients. It is integrated with the
Autodiscover service (discussed in the following section) and improves
on the Exchange 2003 version.
In Exchange
2003, the free/busy information was published in local public folders.
In Exchange 2007, the Availability service is web-based and is accessed
via a uniform resource locator (URL). The service can be load-balanced
with Network Load Balancing (NLB) and can provide free/busy information
in trusted cross-forest topologies.
The Autodiscover service provides the closest availability service URL to the client in the XML file.
The
Availability service is installed by default on each CAS.
Interestingly, there are no Exchange Management Console options for the
Availability service. All interaction with the service is through the
Exchange Management Shell.
Autodiscover Service
In
previous versions of Exchange, profiles were a frequent source of
headaches for administrators. The new Exchange 2007 Autodiscover
feature automatically generates a profile from the user’s email address
and password. The service works with the clients and protocols listed
in Table 4.
Table 4. Autodiscover Supported Clients and Protocols
| Client | Protocol |
|---|
| Outlook 2007 | MAPI (Exchange RPC) Outlook Anywhere (RPC over HTTP) |
| ActiveSync | ActiveSync |
Autodiscover
is an evolution of the Exchange 2003 MAPI referral feature, which would
redirect the user to the appropriate Exchange back-end server and
modify the user’s profile. All that the user needed to provide was
their alias and the name of any Exchange server. This was a very useful
feature if the location of a user’s mailbox would change from one
server to another, as it would automatically redirect the user and
permanently change the profile. This was a marked improvement over the
Exchange 2000 profile generation, which would simply fail if the server
or alias were not specified correctly. Any Exchange server would do and
the user could type their full name, the account name, or even their
email address. However, in Exchange 2003 the user still had to enter
the information to get access.
With
Outlook 2007 and Exchange 2007, it gets even better. The user simply
provides authentication credentials and the Autodiscover service
determines the user’s profile settings. Then, the Autodiscover function
of Outlook 2007 configures the user’s profile automatically, basically
filling in the information automatically. No manual entry of the server
name or username is needed.
When the CAS
is created, a virtual directory is created in the default website on
the CAS server. The CAS role also creates Service Connection Point
(SCP) objects in Active Directory.
When a
client is domain joined and domain connected, the Outlook 2007 client
looks up the SCP records in AD. The client picks the one in its site or
a random one if there is none in its site. It then communicates with
the CAS and gets an XML file with profile information. The Outlook
client consumes this XML file to generate or update its profile.
The
Autodiscover service can also be used by Outlook Anywhere and
ActiveSync clients over the Internet, which requires SSL for security.
The Outlook 2007 client uses the domain portion of the Simple Mail
Transfer Protocol (SMTP) address of the user to locate the Autodiscover
service.
The
Autodiscover service requires the CAS. The Autodiscover service also
requires that the forest in which it resides has the Exchange 2007 AD
schema changes applied.
The functionality
of the Autodiscover service and the Autodiscover feature can be tested
using the Outlook 2007 client. The steps are as follows:
1. | Launch Outlook 2007.
|
2. | Press and hold the Ctrl key, and then select the Outlook icon in the system tray.
|
3. | Select Test E-Mail AutoConfiguration in the menu.
|
4. | The email address should already be populated, so enter the user’s password.
|
5. | Uncheck the Use Guessmart check box.
|
6. | Click the AutoConfigure button.
|
7. | Review the Results, Log, and XML tabs.
|
The log should show a series of three lines in the log with the text:
Attempting URL https://ex1.companyabc.com/Autodiscover/Autodiscover.xml found though SCP
Autodiscover to https://ex1.companyabc.com/Autodiscover/Autodiscover.xml starting
Autodiscover to https://ex1.companyabc.com/Autodiscover/Autodiscover.xml succeeded (0x00000000)
This
shows that the Autodiscover URL was identified from the SCP record in
AD. The client then attempts the autodiscovery and is finally
successful in the last line.
The XML tab
shows (data shown next) the actual file that is returned by the
Autodiscover service. This not only includes information such as the
user’s server and alias, but also information such as the URLs for the
Availability service, Unified Messaging server, and OWA.
<?xml version="1.0" encoding="utf-8"?>
<Autodiscover xmlns="http://schemas.microsoft.com/exchange/autodiscover/responseschema/2006">
<Response xmlns="http://schemas.microsoft.com/exchange/autodiscover/outlook/responseschema/2006a">
<User>
<DisplayName>Chris Amaris</DisplayName>
<LegacyDN>/o=CompanyABC/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=chrisa</LegacyDN>
<DeploymentId>26902be6-4e19-4e1b-a758-a174748122a1</DeploymentId>
</User>
<Account>
<AccountType>email</AccountType>
<Action>settings</Action>
<Protocol>
<Type>EXCH</Type>
<Server>ex1.companyabc.com</Server>
<ServerDN>/o=CompanyABC/ou=Exchange Administrative Group
(FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=EX1</ServerDN>
<ServerVersion>7200825D</ServerVersion>
<MdbDN>/o=CompanyABC/ou=Exchange Administrative Group
(FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=EX1/cn=Microsoft Private MDB</MdbDN>
<ASUrl>https://ex1.companyabc.com/EWS/Exchange.asmx</ASUrl>
<OOFUrl>https://ex1.companyabc.com/EWS/Exchange.asmx</OOFUrl>
<UMUrl>https://ex1.companyabc.com/unifiedmessaging/service.asmx</UMUrl>
<OABUrl>Public Folder</OABUrl>
</Protocol>
<Protocol>
<Type>EXPR</Type>
<Server>ex1.companyabc.com</Server>
<ASUrl>https://ex1.companyabc.com/EWS/Exchange.asmx</ASUrl>
<OOFUrl>https://ex1.companyabc.com/EWS/Exchange.asmx</OOFUrl>
<UMUrl>https://ex1.companyabc.com/unifiedmessaging/service.asmx</UMUrl>
<OABUrl>Public Folder</OABUrl>
<AuthPackage>Basic</AuthPackage>
</Protocol>
<Protocol>
<Type>WEB</Type>
<Internal>
<OWAUrl AuthenticationMethod="Basic"> https://ex1.companyabc.com/owa</OWAUrl>
</Internal>
</Protocol>
</Account>
</Response></Autodiscover>
This information is presented in a neater form on the Results tab.
6. POP and IMAP
Post
Office Protocol (POP) and Internet Message Access Protocol (IMAP) are
legacy messaging protocols that are used mostly by home users and some
third-party applications.
Exchange 2007
supports them for backward compatibility and the services are disabled
by default. To use these protocols, the services must be started on the
CAS.
