Github user mikewalch commented on a diff in the pull request:
https://github.com/apache/incubator-fluo/pull/817#discussion_r107466485
--- Diff: docs/applications.md ---
@@ -114,25 +114,45 @@ To create an observer, follow these steps:
// invert row and value
tx.set(value, new Column("inv", "data"), row);
}
+ }
+ ```
+2. Create a class that implements [ObserverProvider] like the example
below. The purpose of this
+ class is associate a set Observers with columns that trigger the
observers. The class can
+ create multiple observers.
+ ```java
+ class AppObserverProvider implements ObserverProvider {
@Override
- public ObservedColumn getObservedColumn() {
- return new ObservedColumn(new Column("obs", "data"),
NotificationType.STRONG);
+ public void provide(Registry or, Context ctx) {
+ //setup InvertObserver to be triggered when the column obs:data is
modified
+ or.register(new Column("obs", "data"),
+ NotificationType.STRONG,
+ new InvertObserver());
+
+ //Observer is a Functional interface. So Obsevers can be written
as lambdas.
+ or.register(new Column("new","data"),
+ NotificationType.WEAK,
+ (tx,row,col) -> {
+ Bytes combined = combineNewAndOld(tx,row);
+ tx.set(row, new Column("current","data"),
combined);
+ });
}
}
```
-2. Build a jar containing this class and include this jar in the `lib/`
directory of your Fluo
+
+3. Build a jar containing thses classes and include this jar in the
`lib/` directory of your Fluo
application.
-3. Configure your Fluo instance to use this observer by modifying the
Observer section of
+4. Configure your Fluo instance to use this observer factory by modifying
the Observer section of
--- End diff --
should be `observer provider`
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