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09/18/2014

Autodiscover Service Architecture (POX) in Exchange 2010

Last modified: February 08, 2010

Applies to: Exchange Server 2007 | Exchange Server 2010

In this article
Exchange Web Services and Autodiscover (POX)
How the Autodiscover Service Works
Robust Programming
Related Information

The Autodiscover (SOAP) service provides client application configuration information, including external and internal URLs, for Web services, such as Availability and Unified Messaging, that are included in Exchange Web Services. For example, MicrosoftOffice Outlook 2007 uses the Autodiscover service to discover and configure internal and external URLs for the Microsoft Exchange Server 2010 Web services during profile setup and later sessions with the computer that is running Exchange 2010 that has the Client Access server role installed.

Exchange Web Services and Autodiscover (POX)

The Autodiscover service automates part of the deployment of Exchange 2010 client applications by providing configuration information that is used to define the service binding in an Exchange Web Services request. This allows for the development of applications that can automatically reconfigure profile settings, which is useful for clients that connect from different locations and domains.

Note

The POX-based Autodiscover service is now deemphasized in favor of the new SOAP-based Autodiscover Web service. For more information about the SOAP-based Autodiscover Web service, see Autodiscover Service (SOAP) in Exchange 2010.

The Autodiscover service can be located by DNS lookup or Active Directory lookup, depending on whether the client is joined to a domain.

The Autodiscover service uses a user's e-mail address or domain account to provide the following configuration information to Exchange Web Services clients:

The user's display name
Separate connection settings for internal and external connectivity

To create a robust Exchange Web Services client, you should use the Autodiscover service to check for changes to how the client accesses the Client Access server. For example, if the client moves from the intranet to the Internet, it may have to change configurations to access the Client Access server that hosts Exchange Web Services. When the client can connect to the Client Access server, it can try to retrieve updated configuration information by using the Autodiscover service.

The following figure shows how a client on the intranet can use the Autodiscover service to retrieve the service binding to the Exchange Web Services endpoint.

Using the intranet to retrieve the service binding

Autodiscover Configuration for EWS

The following figure shows how a client on the Internet can use the Autodiscover service to retrieve the service binding to the Exchange Web Services endpoint.

Using the Internet to retrieve the service binding

Bb204047.Internet_Autodiscover_SDK(en-us,EXCHG.140).gif

How the Autodiscover Service Works

When you install the Client Access server role on a computer that is running Exchange 2010, a new virtual directory named Autodiscover is created under the default Web site in MicrosoftInternet Information Services (IIS). This virtual directory handles Autodiscover requests from client applications when a new user account is configured or updated, when a user periodically checks for changes to the Exchange Web Services URLs, or when underlying network connection changes occur in the Exchange 2010 messaging environment. Additionally, a new Active Directory directory service object named the service connection point (SCP) is created.

The SCP object contains the authoritative list of Autodiscover service URLs for the forest. You can update the SCP object by using the Set-ClientAccessServer cmdlet.

Important

Before you save the object, make sure that the Authenticated Users account has Read permissions for the object. If users do not have the correct permissions, they will be unable to search for and read items.

When the client connects to Active Directory Domain Services (AD DS), it looks for the SCP object that was created during Setup. In deployments that include multiple Client Access servers, an Autodiscover SCP object is created for each Client Access server. The SCP object contains the ServiceBindingInfo attribute that has the fully qualified domain name (FQDN) of the Client Access server in the form of https://CAS01/autodiscover/autodiscover.xml, where CAS01 is the FQDN for the Client Access server. By using the user credentials, the Exchange Web Services client authenticates to AD DS and searches for the Autodiscover SCP objects. After the client obtains and enumerates the instances of the Autodiscover service, it connects to the first Client Access server in the enumerated list and obtains the profile information in the form of XML data that is needed to connect to the user's mailbox.

Note

The Autodiscover service is also used by Outlook 2007 to retrieve profile information.