Drupal 6 No Longer Supported
The Services module for Drupal 6 is no longer supported, and in fact is not even recommended to be installed on Drupal 6 site's because of a security issue (https://drupal.org/node/2012982). Since DrupalGap relies heavily on this module, there will be no further support for Drupal 6.
What now?
Even though the Services module for Drupal 6 is not at all recommended, you can roll the dice and use it. DrupalGap has a beta branch of the mobile app development kit that can be of used:
https://github.com/signalpoint/DrupalGap/tree/6.x-1.x
The old school versions available for download may also be of use:
https://github.com/signalpoint/DrupalGap/tags
Ultimately though, the Drupal 6 version needs a backport from the 7.x-1.x-alpha (or later) branch to be useful these days. If you would like to sponsor this backport, or contribute code to make it happen, please contact the maintainer(s) of DrupalGap.
Otherwise, proceed with caution.
DrupalGap Module Installation (via Drush, for advanced users)
// Drupal 6
# drush dl drupalgap services libraries views_datasource autoload
// Download spyc.php for the Rest Server.
# cd sites/all/modules/services/servers/rest_server/lib
// (Unix, Linux)
# wget http://spyc.googlecode.com/svn/trunk/spyc.php -O spyc.php
// (OSX)
# curl http://spyc.googlecode.com/svn/trunk/spyc.php -o spyc.php
// Enable DrupalGap.
# drush en drupalgap
Then go to your Drupal site and verify DrupalGap was enabled properly:
admin/settings/drupalgap
Now you're ready to try the DrupalGap Mobile Application or the Mobile Application Development Kit.
DrupalGap Module Installation
1. Download the DrupalGap module and upload it to your 'sites/all/modules' directory.
2. Download The DrupalGap Module Dependencies
- Views JSON (included in the Views Datasource module)
- REST Server* (included in the Services module)
- Autoload
*Before the REST Server module can be enabled, you need to download SPYC and upload the spyc.php file to your drupal site so it lives here, for example:
sites/all/modules/services/servers/rest_server/lib/spyc.php
3. Enable the DrupalGap module dependencies listed above.
4. Enable the DrupalGap module.
5. Flush all of your Drupal caches.
6. Visit admin/settings/drupalgap and verify the module was enabled properly.
7. You're ready to try the Mobile App Development Kit.