need help with Async code

[Sumanth Chinthagunta]

Hi All,
I am new to NiFi and   I'm stuck with couple issues:  

1. Unable to get hold of ControllerService  from Processor’s init method. 
        I wanted to pre-set some dependencies during init phase instead of  
querying them repeatedly in onTrigger method. 
        I am getting null for service and not sure what I have to pass for 
'serviceIdentifier’ . I couldn't find documentation or examples on how to give 
Identifier to a service.  


        final VertxServiceInterface vertxService = (VertxServiceInterface) 
context.getControllerServiceLookup().getControllerService("VertxService”)

        
https://github.com/xmlking/nifi-websocket/blob/master/src/main/java/com/crossbusiness/nifi/processors/PutEventBus.java#L55
 
<https://github.com/xmlking/nifi-websocket/blob/master/src/main/java/com/crossbusiness/nifi/processors/PutEventBus.java#L55>

2. for my usecase I get data published to a topic from EventBus with following 
code. 

        EventBus eb = vertx.eventBus();

        eb.consumer("news.uk.sport", message -> {
                System.out.println("I have received a message: " + 
message.body());
        });
        
        I am working on a date ingest processor (push based) that needs to 
listen for new messages on a topic and send to flow as FlowFile. 
        In my case data source is EvenBus that expose emit messages via 
callback API. 
        I am looking for ideas on how to call Processor’s onTrigger method when 
the above callback is evoked. 
        Should I have to use my own intermediate queue and poll it in onTrigger 
method? 
        is there a better way to trigger the  onTrigger method programmatically 
? 

Thanks 
Sumo