Hi, I been testing wait/notify pattern specially on a process one-by-one pattern (an http rest API can only process 2nd request only after previous completed).
1. i managed to have it work using technique i found here https://community.cloudera.com/t5/Community-Articles/Trigger-based-Serial-Data-processing-in-NiFi-using-Wait-and/ta-p/248308 Basically it tags each ff via statefull UpdateAttribute and then creates a distributedcache key "Release Signal Identifier" with this token (1, 2, ..) and works fine. Wait removes key after consuming/releasing it. 2. but i was unable to understand - i guess - how to implement it uding tooltip suggestion of special values zero(0) or one(1) on both wait.Releasable FlowFile Count and notify.xxxxx which seems suggestion its possible to implement exactly what i want (a flip-flop gate,. where some processing happens serial way one at a time.. but i wasn't able to have this work. It seems both wait/notify Release Signal Identifier would/can be a static value (doesn't matter) as the magic values of zero(close gate) or one(open gate) would be enough... but wasn't able to have this work. Any suggestion please how to have a flip-flop or Singleton or serial processing pattern using the magic values and just 1 Release Signal Identifier? wait.Releasable FlowFile Count "(..)Zero (0) has a special meaning, any number of FlowFiles can be released as long as signal count matches target.(..)" notify.Signal Counter Delta "(..)Zero (0) has a special meaning, it clears target count back to 0, which is especially useful when used with Wait Releasable FlowFile Count = Zero (0) mode, to provide 'open-close-gate' type of flow control. One (1) can open a corresponding Wait processor, and Zero (0) can negate it as if closing a gate.(..)". Ideally would be great if someone could share a minimalistic xml template just demo this capacity suggested by both wait/notify processors documentation. Thanks, Emanuel Oliveira
