When you use the AIR update framework, you define basic
information about the available update in update descriptor files,
stored on your web server. An update descriptor file is a simple
XML file. The update framework included in the application checks
this file to see if a new version has been uploaded.
The format of the update descriptor file changed for AIR 2.5.
The new format uses a different namespace. The original namespace
is “http://ns.adobe.com/air/framework/update/description/1.0”. The
AIR 2.5 name space is “http://ns.adobe.com/air/framework/update/description/2.5”.
AIR applications created prior to AIR 2.5 can only read the version
1.0 update descriptor. AIR applications created using the updater
framework included in AIR 2.5 or later can only read the version
2.5 update descriptor. Because of this version incompatibility,
you often need to create two update descriptor files. The update
logic in the AIR 2.5 versions of your application must download
an update descriptor that uses the new format. Earlier versions
of your AIR application must continue to use the original format.
Both files must be modified for every update that you release (until
you stop supporting versions created before AIR 2.5).
The
update descriptor file contains the following data:
versionNumber—The new version of the
AIR application. Use the versionNumber element
in update descriptors used to update AIR 2.5 applications. The value
must be the same string that is used in the versionNumber element
of the new AIR application descriptor file. If the version number
in the update descriptor file does not match the update AIR file’s
version number, the update framework will throw an exception.
version—The new version
of the AIR application. Use the version element
in update descriptors used to update applications created prior
to AIR 2.5. The value must be the same string that is used in the version element of
the new AIR application descriptor file. If the version in the update descriptor
file does not match the update AIR file’s version, the update framework
will throw an exception.
versionLabel—The human readable version
string intended to be shown to users. The versionLabel is
optional, but can only be specified in version 2.5 update descriptor
files. Use it if you use a versionLabel in the
application descriptor and set it to the same value.
url—The location of the update AIR file.
This is the file that contains the update version of the AIR application.
description—Details regarding the new version.
This information can be displayed to the user during the update
process.
The version and url elements
are mandatory. The description element is optional.
Here is a sample version 2.5 update descriptor file:
<?xml version="1.0" encoding="utf-8"?>
<update xmlns="http://ns.adobe.com/air/framework/update/description/2.5">
<versionNumber>1.1.1</versionNumber>
<url>http://example.com/updates/sample_1.1.1.air</url>
<description>This is the latest version of the Sample application.</description>
</update>
And, here is a sample version 1.0 update descriptor file:
<?xml version="1.0" encoding="utf-8"?>
<update xmlns="http://ns.adobe.com/air/framework/update/description/1.0">
<version>1.1.1</version>
<url>http://example.com/updates/sample_1.1.1.air</url>
<description>This is the latest version of the Sample application.</description>
</update>
If you want to define the description tag using
multiple languages, use multiple text elements
that define a lang attribute:
<?xml version="1.0" encoding="utf-8"?>
<update xmlns="http://ns.adobe.com/air/framework/update/description/2.5">
<versionNumber>1.1.1</versionNumber>
<url>http://example.com/updates/sample_1.1.1.air</url>
<description>
<text xml:lang="en">English description</text>
<text xml:lang="fr">French description</text>
<text xml:lang="ro">Romanian description</text>
</description>
</update>
Place the update descriptor file, along with the update AIR file,
on your web server.
The templates directory included with the update descriptor includes
sample update descriptor files. These include both single-language
and multi-language versions.
