Hey There,

The main method for returning JSON data is to use the Worklist REST Service available through the Web Service Brokers. More information on that is available here:

http://help.k2.com/onlinehelp/K2blackpearl/DevRef/current/default.htm#Using_the_Worklist_Service.html

One thing to note, though, is that REST is not currently fully supported by the Brokers. There is currently a REST Service Broker in BETA that will be available in a future release. If you need to utilize REST services then I would suggest signing up for the BETA, though it is an unreleased product, so there might be some bugs present. 

Ian

Thanks  @K2Ian for the reference.