  The Cherenkov Telescope Array (CTA) Observatory must be capable of issuing
fast alerts on variable and transient sources to maximize the scientific
return. This will be accomplished by means of a Real-Time Analysis (RTA)
pipeline, a key system of the CTA observatory. The latency and sensitivity
requirements of the alarm system impose a challenge because of the large
foreseen data flow rate, between 0.5 and 8 GB/s. As a consequence, substantial
efforts toward the optimization of this high-throughput computing service are
envisaged, with the additional constraint that the RTA should be performed
on-site (as part of the auxiliary infrastructure of the telescopes). In this
work, the functional design of the RTA pipeline is presented.
