Documentation Team/Obsolete/Services Activity Packagers Guide

Introduction
The purpose of this Guide is to describe how to package activities that use Sugar Services.

Activity dependencies
Every activity that uses Sugar Services will contain additional options in an activity.info file:


 * requires option, a comma-separated list of dependencies that should exist,
 * suggests option, a comma-separated list of dependencies that could not exist.

Each dependency could be a,


 * service name, the full 0install link will be http://services.sugarlabs.org/,
 * sub service slashed name, the full 0install link will be http://services.sugarlabs.org/.xml
 * full 0install link.

In any case, the resulting 0install link will contain the appropriate information about dependency - home page, link to sources, licence, etc.

The activity itself doesn't contain any 0sugar-related code. 0sugar will export the appropriate environment variables to the activity process, e.g., PYTHONPATH or LD_LIBRARY_PATH. Thus, dependencies could be packaged and the activity will not notice any differences between 0install dependencies and those installed from packages. An exception is the libsugarize service, which exports the LD_PRELOAD environment variable.

Cache directory
Every activity that uses Sugar Services will contain a .0sugar subdirectory in its activity root

exec $(dirname $0)//0sugar-selector "$@"
 * to keep all necessary dependency implementations (so as not to download them on demand). This could be any content, including binaries.
 * 0sugar launching code, since 0sugar is not part of Sugar Platform. This is pure python code.
 * .0sugar/launch script, which starts 0sugar launching code The exec option from activity.info invokes this script.

If all dependencies (including 0sugar) are packaged, then this directory could be just removed.