colingabr / catsbatsrats

Demo using streamparse to allow a bolt to dynamically choose an emit target. The bolt "hash-bolt" has logic to determine which of the three subscribed bolts to emit to

Cats Bats Rats

Demo using streamparse to allow a bolt to dynamically choose an emit target. The bolt "hash-bolt" has logic to determine which of the three subscribed bolts to emit to.

There are three components which allow this to work:

Output specification (topologies/*.clj) for a bolt or spout, see Clojure-DSL for more info

   ;;streamid ["tuple"]
   ;;the "Cats" bolt will subscribe to the stream of id "c" and so on.
   {"c" ["demon"]
   "b" ["demon"]
   "r" ["demon"]}

Code choosing which streamid to emit to (src/bolts/*.py|src/spouts/*.py)

  streamid = #some computation
  self.emit(["tuples"], stream=streamid)

Input specification (topologies/*.clj)

  ;;subscribe Cats bolt to hash-bolt with streamid "c"
  {["hash-bolt" "c"] :shuffle}