Developers/Stack

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Official description of the Software components on the laptop (XXX maybe merge this into that page, we want links to further information about each library, though?)

Development Languages:

• Python is strongly encouraged, to have a single language "under the hood" when the curious child looks inside
  • C/C++ should be used where Python performance is unacceptable, but try to keep it to a minimum, preferably as standard well-encapsulated and documented components
• Smalltalk-speaking developers may wish to work within the eToys environment
• Javascript can be used in web-based applications (Gecko or Opera engine Javascript implementation)

GUI Environments:

• PyGTK or the PyGTK-derived Sugar system should be used for most "Window, Icon, Mouse, Pointer" type GUIs. Note, however, as of 2007-04-21 that the Sugar "graphics" package is in Flux.
• Pygame SDL-based 2D game environment can be used for "Canvas" graphics using "Sprites".
• (Mozilla) XULRunner can be used to develop Gecko-based activities
• EToys

Operating Stack:

• Hardware
• Firmware (Open Firmware)
• Fedora Core based Operating System
• Bitfrost Security System
• Sugar GUI Shell

Libraries/modules/services of note:

• D-BUS -- efficient Desktop-level RPC engine, most specialized laptop hardware and operations are exposed over DBus
• Telepathy (Glib, Salut, Gabble) -- collaboration/communications engine with "Tubes" (cross-machine RPC over DBus) and various network traversal and discovery logic, activities are encouraged to use Tubes where ever practical
• CSound -- acoustically modelled sound-synthesis engine (seen in the TamTam activity)
• Abiword -- collaborative text editor/word processor usable as a GTK widget that can be embedded in other activities
• SQLite -- lightweight relational database
• XULRunner (with Python DOM-capable bindings) -- Gecko 1.9 (Firefox 3.x) engine
• GStreamer -- general purpose media streaming platform, used for accessing the video camera and playing media
• Avahi -- discovery and advertising mechanism for mesh-hosted services

Common libraries not available:

• OpenGL
• Server-based relational databases (MySQL, PostgreSQL)
• If you are unsure whether something is supported, ask, or load up an emulated machine and check for the presence of the library

Testing/working:

• Announce your project on the OLPC devel list so that people know what you are working on and duplication of effort is reduced
• Add your project to the Software projects page
• Test your application in an official image (or a physical laptop) before publishing broadly
• To conserve memory or improve performance, consider replacing problematic areas in your Python code with C. For example, a rewrite of the hardware manager service in C saved 1.8 megabytes of private dirty memory. On a machine with only 256 megabytes of RAM and no swap space, efficient use of memory can make the difference between a usable system and a system made unreliable by out-of-memory failures.
• Distribute your source code under the GPL, LGPL or MIT license.
• When ready to test with real users add your activity to the Activities page to allow for easy download and installation

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