mikewalch commented on a change in pull request #904: Fixes #897 added context
to application docs and moved some docs from?
URL: https://github.com/apache/fluo/pull/904#discussion_r132262720
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File path: docs/applications.md
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@@ -140,12 +135,123 @@ To create an observer, follow these steps:
3. Build a jar containing these classes and include this jar in the `lib/`
directory of your Fluo
application.
-4. Configure your Fluo instance to use this observer provider by modifying
the Application section of
- [fluo-app.properties].
-5. Initialize Fluo. During initialization Fluo will obtain the observed
columns from the
- ObserverProvider and persist the columns in Zookeeper. These columns
persisted in Zookeeper
- are used by transactions to know when to trigger observers.
-6. Start your Fluo instance so that your Fluo workers load the new observer.
+4. Configure your Fluo application to use this observer provider by modifying
the Application section of
+ [fluo-app.properties]. Set `fluo.observer.provider` to the observer
provider class name.
+5. Initialize your Fluo application as described in the next section. During
initialization Fluo
+ will obtain the observed columns from the ObserverProvider and persist the
columns in Zookeeper.
+ These columns persisted in Zookeeper are used by transactions to know when
to trigger observers.
+
+## Initializing a Fluo Application
+
+Before a Fluo Application can run, it must be initiaized. Below is an
overview of what
+initialization does and some of the properties that may be set for
initialization.
+
+ * **Initialize ZooKeeper** : Each application has its own area in ZooKeeper
used for configuration,
+ Oracle state, and worker coordination. All properties, except
`fluo.connections.*`, are copied
+ into ZooKeeper. For example, if `fluo.worker.num.threads=128` was set, then
when a worker process
+ starts it will read this from ZooKeeper.
+ * **Copy Observer jars to DFS** : Fluo workers processes need the jars
containing observers. These
+ are provided in one of the following ways.
+ * Set the property `fluo.observer.init.dir` to a local directory containing
observer jars. The
+ jars in this directory are copied to DFS under `<fluo.dfs.root>/<app
name>`. When a worker is
+ started, the jars are pulled from DFS and added to its classpath.
+ * Set the property `fluo.observer.jars.url` to a directory in DFS
containing observer jars. No
+ copying is done. When a worker is started, the jars are pulled from this
location and added to
+ its classpath.
+ * Do not set any of the properties above and have the mechanism that starts
the worker process
+ add the needed jars to the classpath.
+ * **Create Accumulo table** : Each Fluo application creates and configures an
Accumulo table. The
+ `fluo.accumulo.*` properties determine which Accumulo instance is used. For
performance reasons,
+ Fluo runs its own code in Accumulo tablet servers. Fluo attempts to copy
Fluo jars into DFS and
+ configure Accumulo to use them. Fluo first checks the property
`fluo.accumulo.jars` and if set,
+ copies the jars listed there. If that property is not set, then Fluo looks
on the classpath to
+ find jars. Jars are copied to a location under `<fluo.dfs.root>/<app name>`.
+
+Below are the steps to initialize an application from the command line. It is
also possible to
+initialize an application using Fluo's Java API.
+
+1. Create a copy of [fluo-app.properties] for your Fluo application.
+
+ cp $FLUO_HOME/conf/fluo-app.properties
/path/to/myapp/fluo-app.properties
+
+2. Edit your copy of [fluo-app.properties] and make sure to set the following:
+
+ * Class name of your ObserverProvider
+ * Paths to your Fluo observer jars
+ * Accumulo configuration
+ * DFS configuration
+
+ When configuring the observer section of fluo-app.properties, you can
configure your instance for the
+ [phrasecount] application if you have not created your own application. See
the [phrasecount]
Review comment:
No link for phrasecount
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