public void process(Processing processing, ProcessingEndpoint endp) {
        processing.setServiceName(getName());
        ((ProcessingAccess)processing).setCallStack(new CallStack(getCallStack()));
        ((ProcessingAccess)processing).setEndpoint(endp);
        addProcessing(processing);
    }
Asynchronously process the given Processing using the processing
chain of this service, and call the specified ProcessingEndpoint when done.

@throws RuntimeException caused by a QueueFullException if this DocprocService has a bounded input queue and the queue is full
@throws IllegalStateException if this DocprocService is not accepting new incoming processings
docproc/src/main/java/com/yahoo/docproc/impl/DocprocService.java