Difference between revisions of "Platform Team/Package Management System"

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[[Category:Activity Team]]
 
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== Summary ==
 
== Summary ==
  
Provides transparent for users and convenient for activity developers, method to support variety of activity dependencies and variety of dependency versions. In other words Services is a common deployment system for activity dependencies, lightweight like sugargame and hightweight like Qt.
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Sweets is a [http://en.wikipedia.org/wiki/Package_management_system Package Management System] entirely based on [http://0install.net/ Zero Install], a decentralized cross-distribution software installation system. It is intended to distribute various software projects created in the Sugar ecosystem, such as libraries, sugar itself, and sugar activities.
 
 
The major difference from existed sugar deployment technics is that Services is activity developers POV system. It doesn't exclude(because reuse them) Sucrose releases or GNU/Linux distribution initiatives but gives activity developers additional(and optional) instrument.
 
 
 
== Work flows ==
 
 
 
How it looks like for:
 
 
 
=== Users ===
 
 
 
In case of poor internet connection(and implemented [[Features/Zero_Install_integration|Zero Install integration]] feature), user can switch to offline mode and won't encounter any changes in regular workflow. Switching to online mode brings additional progress bar to launch dialog for activities that have pending/not-yet-downloaded/out-dated activity dependencies.
 
 
 
=== Activity developers ===
 
 
 
Sugar Services makes sense only for activities that have non Sugar Platform dependencies or support more then one Sucrose release cycles.
 
 
 
For such activities development focus is shifting from Sucrose to API of services they are using. More over activity could be stuck to particular service API version(of course if service developers still support this branch) and Sugar Services will support several branches for the same service simultaneously.
 
 
 
To utilize Services benefits, activity developer just need to [[Activity Team/Documentation/Services/Activity Developers HOWTO|mention all services]] that activity is using and(if activity targeted to sugars w/o [[Features/Zero_Install_integration|Zero Install integration]]) pure python library to initial launch of Services infrastructure. Services infrastructure will provide specified services(and specified versions) for activity and will export environment variables, like LD_LIBRARY_PATH or PYTHONPATH, to activity session, so activity developer shouldn't adapt code to Services.
 
 
 
=== Service developers ===
 
 
 
Services could be:
 
* 3rd party applications that are not included to Sugar Platform e.g. Qt
 
* applications that were not included to all deployed Sugar Platforms e.g. gst-espeak came only from 0.84 and Services will let gst-espeak based activities work even in 0.82 environment
 
* dependencies that are specific to particular activity e.g. some python activities have C libraries, using Services, activity developer should not bundle all binaries that sugar supports but provide links to binaries that he managed to build and let Services build C libraries from sources on user side in the rest of cases
 
  
To create new service developper needs to [[Activity Team/Documentation/Services/Service Developers HOWTO|create and share]] proper feed file which url could be used in activity developers [[Activity Team/Documentation/Services/Activity Developers HOWTO|local feed files]].
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This new distribution method is initiated with these assumptions:
  
=== Geeks ===
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* The method to share software projects should to be as convenient as possible.
 +
* It is important to stimulate users into becoming doers&mdash;to modify existing activities, and to share the results of their experiments with other people, viz., a distribution method should handle different variants of the same project.
 +
* This distribution method is not intended to be the only one, but is targeted more towards direct distribution&mdash;from software creators to software users.
  
The whole Sugar Services feature is nothing but just a sugarized UI around [http://0install.net/ 0install] e.g. feed files that are beeing used in activity bundles are just regular 0install local feeds, so could be used to install/upgrade any software(including sugar core components).
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The goal is to create a new distribution method that goes beyond reusing the current methods:
  
== Detailed Description ==
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# [[Development_Team/Almanac/Activity_Bundles|''.xo bundles'']]
 +
#* Work smoothly only for pure python activities, though only if all (and the same) dependencies are installed on all systems. They stop working smoothly if activities use non-standard dependencies or contain binaries.
 +
#* But, are not effective in supporting the simultaneous use of multiple versions of software, e.g., the results of experiments (the work) of different doers, in one environment. Users must manually handle the variety of activity versions, e.g., sort out all the local bundles or directories in {{Code|~/Activities}}.
 +
# ''native packages''
 +
#* Are not the shortest way to connect developers with users.
 +
#* In most cases, they don't support multiple versions of the same project.
 +
#* They don't work at all for sharing results of experiments.
  
This proposal assumes that the core of sugar development(in common sense) is variety of developers rather then developers who are taking part in sugar core(glucose) development. So, it's all about seeing from activity/3rd-party developers.
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And, at the same time, the existing distribution methods are available for reuse in Sweets:
  
From such new core POV, sugar development process will look like:
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# [[Development_Team/Almanac/Activity_Bundles|''.xo bundles'']] are a subset of the Sweets workflow, from the usage point of view.
* variety of sugar activities
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#* It is possible to bundle an entire directory as a sweet project to use it as a regular .xo file.
* that use Sugar Services
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# ''native packages''
 +
#* Sweets is not intended to create one more GNU/Linux distribution. It distributes only projects that people create within the Sugar community; all other software, i.e., dependencies, will be reused from native packages.
 +
#* For cases like Sugar deployments, using the more centralized, regular repositories (third party or official GNU/Linux distributions with native packages) makes more sense. These native packages of Sugar software will be included in Sweets, as well. When people start using Sweets on top of these Sugar distributions, they will have the chance to choose between natively packaged Sugar components and components that came directly from software creators.
 +
#* It is possible, when there is a need, to automatically package sweets into native packages. See [[Sweets Distribution]], for example.
  
So, developers use a set of services that have theirs own API changes based schedules. Existed glucose could be treated as a big service and splited to several components but thats not a task for this proposal. Instead, it's about proposing basic infrastructure of Sugar Services and several services that are not part of glucose.
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See also the initial release [[Platform_Team/Sweets/1.0/Notes|notes]].
  
The corner stone of Sugar Services proposal is [[Activity_Team/Services/Saccharin|Saccharin]] service. This service provides installing/upgrading(via 0install) mechanism for all other services. The rest of services is just variety of libraries/applications.
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== Zero Install basis ==
  
Technically, service could be a part of glucose(or some of its releases) but from activity POV it doesn't make much sense, if activity requires some service, [[Activity_Team/Services/Saccharin|Saccharin]] will do nothing if requested service/version is a part of installed glucose or install proper service(via 0install). Various activities on the same system could use various versions of the same service, in that case [[Activity_Team/Services/Saccharin|Saccharin]](via 0install) will just provide proper version to particular activity.
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Sweets is entirely based on Zero Install. Sweets might be treated as a tools and infrastructure wrapper around Zero Install. See Zero Install's home page, http://0install.net/, for detailed information. And the [http://0install.net/injector-design.html design] page in particular.
  
=== Versioning scheme ===
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== Further reading ==
  
Each service has API changes based versioning scheme
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* [[Platform_Team/Sweets/Architecture|Sweets Architecture]] - A guide to basic Sweets concepts.
 +
* [[Platform_Team/Guide/Sweets_Usage|Sweets Usage]] - A guide to know how to launch software using Sweets.
 +
* [[Platform_Team/Guide/Sweets_Packaging|Sweets Packaging]] - A guide to know how to make your software accessible via Sweets.
 +
* [[Platform_Team/Infrastructure|Infrastructure Map]] - An overview of the Sweets software world.
  
<major-version>.<minor-version>
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== Getting involved ==
  
* the major version starts from ''0''(premature state) and exposes the fact of API backwards compatibility breakage
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* Read the [http://git.sugarlabs.org/sdk/sweets/blobs/master/HACKING HACKING] file to know how to contribute with code.
* the minor version is for bugfixes and features that don't break backwards compatibility
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{{:Platform_Team/Sweets/Feedback}}
  
== Documentation ==
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== Resources ==
  
{{Special:PrefixIndex/Activity_Team/Documentation/Services/}}
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* [http://git.sugarlabs.org/sdk/sweets Sources].
 +
* Recipe files [[Platform_Team/Recipe_Specification|specification]].
  
== List of services ==
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== Subpages ==
  
{{Special:PrefixIndex/{{PAGENAME}}/}}
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{{Special:PrefixIndex/{{PAGENAMEE}}/}}

Latest revision as of 15:51, 3 July 2012

Summary

Sweets is a Package Management System entirely based on Zero Install, a decentralized cross-distribution software installation system. It is intended to distribute various software projects created in the Sugar ecosystem, such as libraries, sugar itself, and sugar activities.

This new distribution method is initiated with these assumptions:

  • The method to share software projects should to be as convenient as possible.
  • It is important to stimulate users into becoming doers—to modify existing activities, and to share the results of their experiments with other people, viz., a distribution method should handle different variants of the same project.
  • This distribution method is not intended to be the only one, but is targeted more towards direct distribution—from software creators to software users.

The goal is to create a new distribution method that goes beyond reusing the current methods:

  1. .xo bundles
    • Work smoothly only for pure python activities, though only if all (and the same) dependencies are installed on all systems. They stop working smoothly if activities use non-standard dependencies or contain binaries.
    • But, are not effective in supporting the simultaneous use of multiple versions of software, e.g., the results of experiments (the work) of different doers, in one environment. Users must manually handle the variety of activity versions, e.g., sort out all the local bundles or directories in ~/Activities.
  2. native packages
    • Are not the shortest way to connect developers with users.
    • In most cases, they don't support multiple versions of the same project.
    • They don't work at all for sharing results of experiments.

And, at the same time, the existing distribution methods are available for reuse in Sweets:

  1. .xo bundles are a subset of the Sweets workflow, from the usage point of view.
    • It is possible to bundle an entire directory as a sweet project to use it as a regular .xo file.
  2. native packages
    • Sweets is not intended to create one more GNU/Linux distribution. It distributes only projects that people create within the Sugar community; all other software, i.e., dependencies, will be reused from native packages.
    • For cases like Sugar deployments, using the more centralized, regular repositories (third party or official GNU/Linux distributions with native packages) makes more sense. These native packages of Sugar software will be included in Sweets, as well. When people start using Sweets on top of these Sugar distributions, they will have the chance to choose between natively packaged Sugar components and components that came directly from software creators.
    • It is possible, when there is a need, to automatically package sweets into native packages. See Sweets Distribution, for example.

See also the initial release notes.

Zero Install basis

Sweets is entirely based on Zero Install. Sweets might be treated as a tools and infrastructure wrapper around Zero Install. See Zero Install's home page, http://0install.net/, for detailed information. And the design page in particular.

Further reading

Getting involved

  • Read the HACKING file to know how to contribute with code.
  • Submit your bug report or feature request.
  • Subscribe to the sugar-devel mailing list and email with the subject prefixed with [SWEETS].
  • Ask your question on IRC channels, #sugar (not logged) or #sugar-newbies (logged).

Resources

Subpages