In some cases, the BE application needs to consume messages (e.g. EMS, Kafka) with JSON payloads which have no root element. For example:
 

 {   "BookTitle":"Finnegans Wake",   "BookAuthor":"James Joyce",   "BookPrice":24.98 }

First, configure the Payload in the Event definition with Content = Any Element:



Next, define properties for the Concept that will be instantiated when a new message arrives:



Next, create a RuleFunction to serve as a pre-processor for the incoming messages, and use the createInstanceFromJSON() function. For example:

 void rulefunction RuleFunctions.PreProc {   attribute {     validity = ACTION;   }   scope {     Events.BookDataEvent bookdataevent;   }   body {     System.debugOut("*** Instantiating BookData Concept ****");     Concepts.BookDataConcept bdInst = Instance.createInstanceFromJSON("/Concepts/BookDataConcept",bookdataevent@payload);     System.debugOut("*** New BookDataConcept: "+bdInst.BookTitle         +" by " + bdInst.BookAuthor + " ("+bdInst.BookPrice+")");   } }

Finally, at either the cluster or processing-unit level, set the property 'be.http.json.rootElement.ignore' to 'true':



You should see the following message emitted to the console:

 2021 Nov 19 06:58:45:995 GMT -05 dev.machine INFO [$default.be.mt$.Thread.7] - [user] [jms]  *** New BookDataConcept: Finnegans Wake  by James Joyce (24.98)