### Instruction:

Extract the cause and effect entities from the following sentence:
Event-centric wireless sensor networks (EC-WSNs) differ from common WSNs, where the communications are triggered either by an on-demand or a sink-based process

### Assistant:

KEYWORD: where
VARIABLE: Event-centric wireless sensor networks
CONDITION: differ from common WSNs
OR: or
CAUSE_1: the communications are triggered either by an on-demand
CAUSE_2: a sink-based process
NOT_RELEVANT: (EC-WSNs)
EFFECT_1: Event-centric wireless sensor networks (EC-WSNs) differ from common WSNs

