Initializing an Application

To enable installer functionality, an application must call a number of functions when it is initializing. For more information, see Installation Mechanism. The following steps describe how to use the installer to initialize an application:

To initialize an application

1. Call the MsiGetProductCode function so the application can identify itself to the installer.

   The product code is a required parameter for many installer functions.

2. Call the MsiGetUserInfo function to collect user information the first time the application starts.

   If the call to MsiGetUserInfo fails, call the MsiCollectUserInfo function to collect user information.

3. Display a default user interface, if necessary, by calling the MsiSetInternalUI function.

   To author your own user interface, register it with the installer by calling the MsiSetExternalUI function.

4. Call the MsiEnableLog function to set the logging level.
5. Present the user with available features by enumerating the features of your application. You can enumerate features in the following ways:
   • Query the installer feature-by-feature. For example, before the application draws a button or a menu item, the application calls the MsiQueryFeatureState function so the installer can check that the feature is available.
   • Enumerate all of the available features at once by calling the MsiEnumFeatures function. To use this function, the application must call MsiEnumFeatures repeatedly while incrementing an index.
6. Get detailed information about the current installation by calling the following enumeration functions repeatedly, incrementing an index variable for each call:
   • Call the MsiEnumProducts function to enumerate products registered with the installer.
   • Call the MsiEnumComponents function to enumerate components.
   • Call the MsiEnumComponentQualifiers function to enumerate component qualifiers.
   • Call the MsiEnumClients function to enumerate the products for a particular component.

   If the return value on an enumeration function is ERROR_SUCCESS, there are still more items to be enumerated and the function should be called again with an incremented index variable. If the return value is ERROR_NO_MORE_ITEMS, then all of the items have been enumerated, and the function should not be called again.