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The Updater class (in the flash.desktop
package) includes one method, update(), which you
can use to update the currently running application with a different
version. For example, if the user has a version of the AIR file ("Sample_App_v2.air")
located on the desktop, the following code updates the application.
ActionScript example:
var updater:Updater = new Updater();
var airFile:File = File.desktopDirectory.resolvePath("Sample_App_v2.air");
var version:String = "2.01";
updater.update(airFile, version);
JavaScript example:
var updater = new air.Updater();
var airFile = air.File.desktopDirectory.resolvePath("Sample_App_v2.air");
var version = "2.01";
updater.update(airFile, version);
Before an application uses the Updater class, the user or the
application must download the updated version of the AIR file to
the computer. For more information, see Downloading an AIR file to the user’s computer.
Results of the Updater.update() method callWhen
an application in the runtime calls the update() method,
the runtime closes the application, and it then attempts to install
the new version from the AIR file. The runtime checks that the application
ID and publisher ID specified in the AIR file matches the application
ID and publisher ID for the application calling the update() method.
(For information on the application ID and publisher ID, see AIR application descriptor files.) It also checks that the version
string matches the version string passed to the update() method.
If installation completes successfully, the runtime opens the new
version of the application. Otherwise (if the installation cannot
complete), it reopens the existing (pre-install) version of the
application.
On Mac OS, to install an updated version of an application, the
user must have adequate system privileges to install to the application
directory. On Windows and Linux, a user must have administrative
privileges.
If the updated version of the application requires an updated
version of the runtime, the new runtime version is installed. To
update the runtime, a user must have administrative privileges for
the computer.
When testing an application using ADL, calling the update() method
results in a runtime exception.
About the version stringThe string that is specified as the version parameter
of the update() method must match the string in
the version or versionNumber element
in the application descriptor file for the AIR file to be installed.
Specifying the version parameter is required for
security reasons. By requiring the application to verify the version
number in the AIR file, the application will not inadvertently install
an older version. (An older version of the application might contain
a security vulnerability that has been fixed in the currently installed
application.) The application should also check the version string
in the AIR file with version string in the installed application
to prevent downgrade attacks.
Prior to AIR 2.5, the version string can be of any format. For
example, it can be "2.01" or "version 2". In AIR 2.5, or later,
the version string must be a sequence of up to three, three-digit
numbers separated by periods. For example, “.0”, “1.0”, and “67.89.999”
are all valid version numbers. You should validate the update version string
before updating the application.
If an Adobe AIR application downloads an AIR file via the web,
it is a good practice to have a mechanism by which the web service
can notify the Adobe AIR application of the version being downloaded.
The application can then use this string as the version parameter
of the update() method. If the AIR file is obtained by
some other means, in which the version of the AIR file is unknown,
the AIR application can examine the AIR file to determine the version
information. (An AIR file is a ZIP-compressed archive, and the application
descriptor file is the second record in the archive.)
For details on the application descriptor file, see AIR application descriptor files.
Signing workflow for application updatesPublishing updates in an ad-hoc manner complicates the
tasks of managing multiple application versions and also makes tracking
certificate expiry dates difficult. Certificates may expire before
you can publish an update.
Adobe AIR runtime treats an application update published without
a migration signature as a new application. Users must uninstall
their current AIR application before they can install the application
update.
To resolve the problem, upload each updated application with
the latest certificate to a separate deployment URL. Include a mechanism
that reminds you to apply migration signatures when your certificate
is within the 180 days grace period. See Signing an updated version of an AIR application for more information.
See ADT commands for information on how to apply signatures.
Perform the following tasks to streamline the process of applying
the migration signatures:
Upload each updated application to a separate deployment
URL.
Upload the upgrade descriptor XML file and the latest certificate
for the update to the same URL.
Sign the updated application with the latest certificate.
Apply a migration signature to the updated application with
the certificate used to sign the previous version located at a different
URL.
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