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From Keith Turner <ke...@deenlo.com>
Subject [DISCUSS] New API for setting up observers.
Date Thu, 23 Feb 2017 22:36:35 GMT
The current way observers are set up in Fluo requires specifying a
class for each observers in configuration.  This is cumbersome and
prevents using lambdas and anonymous inner classes.  It also makes it
hard to follow what a Fluo Application is doing.  This cumbersome way
of setting things up propagates forward into higher level constructs
in Fluo Recipes making them also cumbersome to use.

I think it would be much simpler if the user only had to specify one
factory class in configuration that created all observers.  This
factory would be free to pair a lambda with a column for an observer.
Observed columns would no longer be tightly coupled with a specific
class.  I am thinking the factory would look something like the

interface ObserversFactory {
  Map<ObservedColumn, Observer> getObservers(SimpleConfiguration

A user would implement this interface with a class that creates all of
their observers.

class UserObserversFactory implements ObserversFactory {
  Map<ObservedColumn, Observer> getObservers(SimpleConfiguration appConfig) {
    //all of users observers are setup here in code, which is much
easier to follow than current way of configuring each observer class
     HashMap observers = ...;
     observers.put(col1, tx,row,col -> ....); //an observer that's a lambda
     ExportQueue.addObserver(observers, appConfig, "queueId", exports
-> ....);  //using a lambda to handle exports...

The user would configure Fluo to use the above observer factory.

I am thinking of trying to implement this for 1.1, but wanted to see
if anyone had any input before I started.  If it seems to work well, I
was thinking of deprecating the current way of configuring observers.
I would update webindex and fluo recipes in parallel to evaluate the

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