Github user drigodwin commented on a diff in the pull request:
https://github.com/apache/brooklyn-docs/pull/160#discussion_r109779180
--- Diff: guide/java/enrichers.md ---
@@ -0,0 +1,150 @@
+---
+title: Enrichers
+layout: website-normal
+toc: ../guide_toc.json
+categories: [use, guide, defining-applications]
+---
+
+Enrichers provide advanced manipulation of an entity's sensor values.
+
+#### Transformer
+
+- org.apache.brooklyn.enricher.stock.Transformer
+
+Transforms attributes of an entity.
+
+{% highlight yaml %}
+brooklyn.enrichers:
+- type: org.apache.brooklyn.enricher.stock.Transformer
+ brooklyn.config:
+ enricher.sourceSensor: $brooklyn:sensor("urls.tcp.string")
+ enricher.targetSensor: $brooklyn:sensor("urls.tcp.withBrackets")
+ enricher.targetValue: $brooklyn:formatString("[%s]",
$brooklyn:attributeWhenReady("urls.tcp.string"))
+{% endhighlight %}
+
+#### Propagator
+
+- org.apache.brooklyn.enricher.stock.Propagator
+
+Use propagator to duplicate one sensor as another, giving the supplied
sensor mapping.
+The other use of Propagator is where you specify a producer (using
`$brooklyn:entity(...)` as below)
+from which to take sensors; in that mode you can specify `propagate` as a
list of sensors whose names are unchanged,
+instead of (or in addition to) this map
+
+{% highlight yaml %}
+brooklyn.enrichers:
+- type: org.apache.brooklyn.enricher.stock.Propagator
+ brooklyn.config:
+ producer: $brooklyn:entity("cluster")
+- type: org.apache.brooklyn.enricher.stock.Propagator
+ brooklyn.config:
+ sensorMapping:
+ $brooklyn:sensor("url"):
$brooklyn:sensor("org.apache.brooklyn.core.entity.Attributes", "main.uri")
+{% endhighlight %}
+
+#### Custom Aggregating
+
+- org.apache.brooklyn.enricher.stock.Aggregator
+
+Aggregates multiple sensor values (usually across a tier, esp. a cluster)
and performs a supplied aggregation method to them to return an aggregate
figure, e.g. sum, mean, median, etc.
+
+{% highlight yaml %}
+brooklyn.enrichers:
+- type: org.apache.brooklyn.enricher.stock.Aggregator
+ brooklyn.config:
+ enricher.sourceSensor: $brooklyn:sensor("webapp.reqs.perSec.windowed")
+ enricher.targetSensor: $brooklyn:sensor("webapp.reqs.perSec.perNode")
+ enricher.aggregating.fromMembers: true
+ transformation: average
+{% endhighlight %}
+
+#### Joiner
+
+- org.apache.brooklyn.enricher.stock.Joiner
+
+Joins a sensor whose output is a list into a single item joined by a
separator.
+
+{% highlight yaml %}
+brooklyn.enrichers:
+- type: org.apache.brooklyn.enricher.stock.Joiner
+ brooklyn.config:
+ enricher.sourceSensor: $brooklyn:sensor("urls.tcp.list")
+ enricher.targetSensor: $brooklyn:sensor("urls.tcp.string")
+ uniqueTag: urls.quoted.string
+{% endhighlight %}
+
+#### Delta Enricher
+
+- org.apache.brooklyn.policy.enricher.Delta Enricher
+
+Converts absolute sensor values into a delta.
+
+#### Time-weighted Delta
+
+- org.apache.brooklyn.enricher.stock.YamlTimeWeightedDeltaEnricher
+
+Converts absolute sensor values into a delta/second.
+
+{% highlight yaml %}
+brooklyn.enrichers:
+- type: org.apache.brooklyn.enricher.stock.YamlTimeWeightedDeltaEnricher
+ brooklyn.config:
+ enricher.sourceSensor: reqs.count
+ enricher.targetSensor: reqs.per_sec
+ enricher.delta.period: 1s
+{% endhighlight %}
+
+#### Rolling Mean
+
+- org.apache.brooklyn.policy.enricher.RollingMeanEnricher
+
+Converts the last *N* sensor values into a mean.
--- End diff --
Is N a config value to the enricher? What's it's key?
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
