Sprint Developers

A General Content Descriptor (GCD) file is similar to a JAD file. While a JAD describes a J2ME MIDlet for download, a GCD describes downloads like ringtones and pictures. GCD's are plain text files and you can create them using any simple text editor like Windows Notepad. If you'd like your phone to download your own picture, then you'll need a GCD file.

Serving Ringtones

If you plan to serve ringtones or pictures from your own website then make sure your webserver has the proper MIME type for GCD files. Specifically:

File extension:  .gcd   Content-handler type:  text/x-pcs-gcd

If you are trying to use a website like GeoCities or AOL then you have a problem. Most ISPs will not allow you to define new MIME types and they will not have the GCD type already defined for you. You need to use a server where you have more control. For example, on an Apache server you'd modify the .htaccess file. Again, this is something that most ISPs won't allow you to do.

For more information read the "Setup a Mobile Website" article.

More MIME Types

What do you plan to distribute? A JPEG picture? A MIDI ringtone? Each different type of content has a corresponding MIME definition. To create a GCD, you need to know what MIME type matches your download. Here's some common ones:

File Extension	MIME Type
.jpg	image/jpeg
.gif	image/gif
.png	image/png
.mid	audio/midi
.qcd	audio/vnd.qcelp

GCD Example

Here's an example of a GCD file

Content-Type: image/jpeg
Content-Name: William
Content-Version: 1.0
Content-Vendor: ApGap.com
Content-URL: http://www.apgap.com/pictures/William.jpg
Content-Size: 2405

What's All That Stuff?

Everything you put in the GCD can be displayed using most (all?) Sprint handsets. It varies from model to model, but look for a "properties" option in your download menu. On my T608, I highlight the downloaded item, press the options key, and select "Properties" to see the GCD.

Other than being able to read it, there's not much point to the vendor and version. Nothing exciting there.

The size is required and must exactly match the size (in bytes) of the content you're downloading. The URL is also essential since it directs the phone where to go to actually get the content. This needs to be a fully qualified URL starting with "http://".

The name is about the most interesting thing in the GCD file. It will be the label for your content in the download menu on your phone. You could freak somebody out by using a name like "Erase All" and then add a picture of a skull and cross bones. A novice user might think you magically added a command to their phone.

Try the Uploader

Sprint Developers has an upload tool you can use if you'd just like to transfer a couple files to your phone. You don't have to set up a mobile website. Just fill in the form at uploader.sprintdevelopers.com.