Sugar Labs

Platform Team/Package Management System

< Platform Team
Revision as of 19:00, 6 March 2010 by FGrose (talk | contribs) (work on English)


Zero Sugar Distribution

Sugar Services provides a method that is transparent for users and convenient for activity developers to support activity dependencies across varying platforms (and their varying dependencies) as well as across Sugar releases. In other words, Services is a common deployment system for activity developers' needs.

See Scalable development model to learn more about the initial intentions for Sugar Services.

Workflows

Sugar Services look different depending upon your point of view:

Users

In the case of a poor Internet connection (and a Zero Sugar Activities-implemented feature), users can switch to offline mode and they won't encounter any changes to their regular workflow. Switching to online mode will bring an additional progress bar to the launch dialog for activities that have pending/not-yet-downloaded/out-dated activity dependencies.

Activity developers

Sugar Services make sense for activities that have non-Sugar Platform dependencies or support more then one Sucrose release cycle.

To utilize the benefits of Services, activity developers need only to mention all services that their activity is using. The Services infrastructure will provide specified services (and specified versions) for the activity and the service will let the activity know about them.

Sugar Services will let activity developers:

  • use dependencies that are not intended to be included in the Sugar Platform,
    • include libraries that are used by only a few activities; or
    • have shorter or longer release/support schedules than Sucrose;
  • deploy dependencies that are specific to a particular activity; for example, some Python activities include C libraries—by using Services, an activity developer need not bundle these binaries, they could be used as regular activity dependencies.

See the Activity Developers Guide to know how to add service dependencies to your activity.

All Sugar developers

Services are intended to decentralize the Sugar development process. If you have some idea in mind, you can start pushing it through the Sucrose release queue to get it into an upcoming (maybe not the nearest) release. However, since the release process is binary—either your feature is included or not—Services offers more flexibility. For example:

  • some features are of arguable general benefit; Sugar Services would allow interested end users to efficiently test (and even deploy) such features;
  • some feature are only stable in limited environments; Sugar Services would allow deployment in limited environmets without the risk of destabilizing the rest of Sugar.

A developer benefits from 0install features by:

  • letting users of all deployed Sucrose releases benefit from your new feature instead of having it only in a specific (latest) Sucrose release; for example Activity Triggers services;

See Service Developers Guide to learn how to create a service.

GNU/Linux distributions

The Sugar Platform cannot grow endlessly, e.g., installing sugar from packages should not fetch half of all available packages including several UI toolkits, several programming languages, etc., so components like Qt or Ruby are (at least at present) out of the Sugar Platform list. But with Sugar Services, activities can still use such dependencies by installing them from native packaging systems on demand and without bundling binaries.

See Native packages usage to know how to utilize native packages in your activity or service.

FAQ

A short list of questions that describe Sugar Services' purposes.

What is Sugar Services not?

  • It is not intended to cure all ills.
  • It is not a "must have" for activity developers; use it only if you really need it.
  • Is is not a replacement for GNU/Linux distributions' Sugar packaging efforts; Sugar Services places no need for special treatment regarding dependencies as part of the Sugar Platform.
  • It is not intended to be used to support large packages (such as Qt or Firefox) in parallel with distributions. Sugar Services should not be used to avert scenarios such as "It is too bad that you don't have Firefox-3.5 in your three-year-old distribution and cannot run the latest Browse activity." In such cases, we should require that users update their distribution and Sugar Platform to more recent versions.

How is Sugar Services different?

  • From the point of view of 0install: Sugar Services is just a method to create a 0install infrastructure; think about "apt" vs. "dpkg" or "yum" vs. "rpm". In other words, Sugar Services are an analog of the 0release command localized to Sugar needs.
  • From the point of view of PackageKit: PackageKit provides a distribution-agnostic method to install already packaged software. Via 0install, Sugar Services let users install unpackaged software as well. Moreover, 0install will use PackageKit to install missing dependencies if they present in a user's distribution.
  • From the point of view of GNU/Linux distributions: see the 0install original goals.

Documentation

Start your exploration with:

Or open the services documentation category page.

List of services

To see the entire list of services, go to http://download.sugarlabs.org/services/.

TODO

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