
435Real-Time Big Data Processing for Domain Experts
Runtime Stream Processing
At runtime, that is, immediately after the conguration phase, the process-
ing tasks dened in spXML are encoded into a suitable stream processor
instance, ready to perform the needed computations. In such a phase, on-line
processing can start provided that actual event producers and consumers
have been “connected” to the processor sources and drains. This is typically
done through a collection (on the input side) and an output layer, dealing
with event capture/delivery logic. Depending on the application domain, the
collection layer can either be a web service ...