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Outlook Web App Customization Architecture

This topic describes the relationship between the files that are used to customize Microsoft Office Outlook Web App in Microsoft Exchange Server 2010, and the features that those files affect.

Outlook Web App Customization Files

The files that enable Outlook Web App customization are stored in the Exchange installation folder, in the ClientAccess\Owa\forms\Customization subfolder. This folder contains template files for the forms registry and the user interface extensions. When you are customizing the user interface, place all files that are related to the customization into this folder. When you are creating a custom form, create a folder inside the ClientAccess\Owa\forms folder. Name the folder for your custom form; for example, "MyCustomForm".

Forms Registry File

Outlook Web App can display an .aspx page for custom content classes when the class has been registered in a forms registry file. The forms registry file specifies which forms are used to display the custom content class item for a particular action. For example, a custom content type might have to display different forms for creating, reading, and replying to a message. Each form can be registered in the forms registry.

Inside the ClientAccess\Owa\forms\Customization folder is a template forms registry file that is named registry.xml.template. When you are registering a new custom form, copy that file into the folder for the forms and rename it to remove the template extension; for example, forms\MyCustomForm\registry.xml. Edit the registry.xml file to specify the forms and actions that you want Outlook Web App to use.

Outlook Web App in Exchange 2010 supports registering custom forms for content items, but does not support registering custom forms on folders.

Outlook Web App looks for and reads all the registry.xml files in any folders that it finds in the forms folder.

Forms Registry File Entries

Each registry.xml file specifies the forms, states, and actions for custom items and folders. Inside the XML file, each custom form registration entry indicates the content class to which the registry entries apply, and the user action that will trigger the use of the specified form. For an example of a complete forms registry file, see the registry.xml file that is located inside the ClientAccess\Owa\forms\premium folder.

Forms Registration and Outlook Web App Segmentation

Exchange 2010 includes the concept of segmentation for Outlook Web App. By using the segmentation features, administrators can control which Outlook Web App features are available to users. Custom forms that are registered in the registry.xml files can take advantage of the segmentation feature by indicating which features must be enabled. If the required feature is not available, the registered forms will also be disabled.

For more information about segmentation, see Configure Segmentation in Outlook Web App on Microsoft TechNet.

User Interface Extensions File

You can add items to the New drop-down menu, add items to the navigation pane, add items to the right-click (context menu), and register small icons to distinguish custom content classes.

You change the Outlook Web App user interface by copying the UIExtensions.xml.template file that is located in the forms\Customization folder. Create a copy of that file in the forms\Customization folder, and rename the file to UIExtensions.xml.

Unlike the registry.xml file, each Outlook Web App forms area can have only one UIExtensions.xml file.

User Interface Extensions File Entries

The UIExtensions.xml file provides sections for specifying icons that will be displayed in the navigation pane for custom content classes. The UIExtensions.xml file also includes sections to specify navigation pane extensions, additional items to be shown in the New drop-down menu, and items to be added to the right-click (context) menu.

Icon Image Files

The Outlook Web App navigation pane uses two icon sizes, depending on how many icons must be displayed. If more than four icons must be displayed, Outlook Web App uses 16x16 pixel icon images. If four or fewer icons are displayed, Outlook Web App uses 24x24 pixel icon images.

The number of icons that are displayed is the sum of the number of MainNavigationBarEntry elements in the UIExtensions.xml file and the number of standard icons that Outlook Web App displays. The Outlook Web App segmentation settings determine which standard icons are displayed.

Theme Files

Outlook Web App in Exchange 2010 reads theme files from the \Client Access\OWA\<version>\themes folder, where <version> can be either "premium" or "basic." Outlook Web App in Exchange 2010 obtains theme information from only the Base theme folder. There can only be one theme in Exchange 2010, and that theme is displayed to all users accessing Outlook Web App from that Client Access server. The additional folders named "1", "2" and "3" must be present, but are not used. Do not modify those folders.