public void addCallback(String streamId, StreamCallback streamCallback) {
        streamCallback.setStreamId(streamId);
        StreamJunction streamJunction = streamJunctionMap.get(streamId);
        if (streamJunction == null) {
            throw new DefinitionNotExistException("No stream found with name: " + streamId);
        }
        streamCallback.setStreamDefinition(streamDefinitionMap.get(streamId));
        streamCallback.setContext(siddhiAppContext);
        streamJunction.subscribe(streamCallback);
    }
Get the names of the available queries.

@return string set of query names.
modules/siddhi-core/src/main/java/io/siddhi/core/SiddhiAppRuntimeImpl.java