We shall review two concepts, one introduced by Beilinson and Drinfeld, another by Costello and Gwilliam and show in an example how the latter leads to the former.
Links:
[1] http://www.mpim-bonn.mpg.de/taxonomy/term/39
[2] http://www.mpim-bonn.mpg.de/node/3444
[3] http://www.mpim-bonn.mpg.de/node/3946
[4] http://www.mpim-bonn.mpg.de/node/5275