Add small discussion about social networks

wiki/net2o.md

@@ -122,6 +122,7 @@ point:
 * [Nettie logo](nettie.md)
 * [$quid CryptoCurrency](squid.md)
 * [Guidelines of Conduct](guidelines.md)
+* [Social network](social.md)
 
 [de](/net2o/wiki?name=net2o.de)
 [中文](net2o.zh.md)

wiki/social.md

+# Using net2o as social network #
+
+When Google+ shut down, I took the opportunity to accelerate my plans on
+running social networks over net2o.  How does a social network over a
+peer2peer network look like and what's the challenge?
+
+## Data structure of social network postings ##
+
+* Timelines are kept as chat logs.  Each posting is a chat log entry, which
+  contains a short teaser of the posting, possibly a thumbnail image, and a
+  link to a DVCS project.
+* A thread (posting+comments) is a DVCS project.  That by itself is another
+  chat log, with each checkin as log entry.  Checkins contain a reference to a
+  file that highlights the posting/comment added in the checkin.  Likes are
+  just messages with a like emoji and a reference to the checkin that is
+  liked.  The DVCS as base to organize a thread allows editing.  It's even
+  possible to collaboratively edit if permissions allow.
+* A posting itself is a markdown file.  Images and videos are in jpeg/png and
+  mkv format.
+
+## Importing data from other networks ##
+
+One thing that is annoying with new networks is that they start all empty.
+You leave all your postings behind in the old network.  But the GDPR allows to
+take out data, and if everything is fine, it's possible to convert that data.
+
+I wrote an importer for Google+, which is mostly complete by now, and also
+started with Blogger.com, Twitter, and Facebook importers.  Other importers
+will follow.
+
+## Connecting to other social networks ##
+
+While in general, a connector to a plattform is a bad idea, for social
+networks, where publicity matters, connectors can have some place, at least
+for the transition period.  Though I have not attempted to actually write one;
+but at least for networks that have an API, you could import feeds into
+net2o, and (with severe limitations) crosspost from net2o.