Design Process : Interface Namespaces
=====================================

[grid="all"]
`------------`-----------------------
*State*         _Final_
*Date*          _2008-09-18_
*Proposed by*   link:ct[]
-------------------------------------

Interface Namespaces
--------------------
Interfaces and their implementations (plugins) need unique identifiers. We
describe here what schemes shall be used to ensure this.

Description
~~~~~~~~~~~
What are the goals?

 * We need unique identifiers.
 * We dont want anyone to register at us, this shall be a free system.
 * There are 2 kinds, one bound to persons and one to projects as whole.
 * Uniquenes, not identity is the goal, plugins could even be provided
   anonymously.
 * This is the lowest level interface stuff, usually you'll deal with a
   high-level descriptor interface which provides much better (human readable)
   metainformation about a plugin.
 * The names should follow C identifier rules and either not to hard to deciper
   for a human or completely abstracted into a numeric ID like gpg id or uuid
 * Conclusion followed some mailinglist and IRC discussion: (see
   http://lists.lumiera.org/pipermail/lumiera/2008-September/000054.html)[]

First part: unique prefix
~~~~~~~~~~~~~~~~~~~~~~~~~

Domain names and emails names encoding
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Domain names in lowercase, dots and special chars removed, first char must be a
aphphanumeric character (if it is numeric, just write it out):

------------------------------------------------------------
 lumiera.org -> lumieraorg
 Gmail.COM -> gmailcom
 99foo-bar.baz.net -> ninetyninefoobarbaznet
------------------------------------------------------------

These are used when the provider is a project and not an individual person.

If the provider of a interface is a individual person then he encodes his email
address in a similar way The @ sign is encoded as uppercase "AT":


------------------------------------------------------------
 7of9@star-trek.net -> sevenofnineATstartreknet
------------------------------------------------------------

Abstract identifiers
^^^^^^^^^^^^^^^^^^^^

As alternative method one can use his gpg (or pgp) key ids or full
fingerprints. These are encoded as uppercase 'PGP' or 'GPG' followed with a
sequence of hex digits (both upper and lower case allowed):


------------------------------------------------------------
 GPGAC4F4FF4
 PGP09FF1387811ADFD4AE84310960DEA1B8AC4F4FF4
------------------------------------------------------------

Next completely random identifiers (uuid's) are used by prefixing them with
uppercase "UID" followed by some alphanumeric characters (no underline), no
encoding is specified but must conform to be a C identifier, shall give a
entropy of 128 bits:

------------------------------------------------------------
 UIDd557753400ad4ac6912773b1deb4d99d
------------------------------------------------------------

 Remarks: this are now quite a lot more or less unique encodings, notably  we
 could allow them all, they dont clash with each other. They would be parseable
 if needed, but we never ever need to parse them, they are just taken as whole
 and have no other meaning then being unique.


Following Parts: hierachic namespace
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Lumiera itself will use some hierachic naming scheme for it interface
declarations and implementations. The details will be layed out next,
genereally thinks look like:

------------------------------------------------------------
 lumieraorg_backend_frameprovider
 lumieraorg_plugin_video
------------------------------------------------------------

it is suggested that anyone providing plugins for lumiera follows this and
extends it with his own identifier:

for examle joecoder``@freevideo.org writes a ultrablur then its identifier
would look like:

------------------------------------------------------------
 joecoderATfreevideoorg_plugin_video_ultrablur
------------------------------------------------------------




Tasks
~~~~~
The above described scheme will be implemented and used by me (cehteh).




Rationale
~~~~~~~~~
I believe that writing plugins for Lumiera shall be simple. We do not want some
central registry or management. Anyone shall be able to just start to write
plugins. But that puts some reponsibility on the namespace so that all plugins
can coexist and their names don't clash. The above describes a very simple and
flexible nameing system which anyone can follow. It produces names which should
be sufficiently unique for practical purposes. It leaves alternatives for
providing plugins as institutuion, individual or even anonymously.


Conclusion
----------
Accepted by October.2008 developer meeting


Addendum Internal Interfaces
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Interfaces which are internal and not meant for public use have 2 underscores
after the prefix (eg: `lumieraorg__`). These interfaces must not be used by
third party plugins, they are subject of unannounced changes or removal and
make no guarantee about backwards compatibility. When we spot someone using
this interfaces we ''will break'' his plugin ''intentionally''!
 -- link:ct[] [[DateTime(2008-10-24T03:43:43Z)]]

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