Github user thvasilo commented on a diff in the pull request:
https://github.com/apache/flink/pull/727#discussion_r31055461
--- Diff: docs/libs/ml/contribution_guide.md ---
@@ -20,7 +21,329 @@ specific language governing permissions and limitations
under the License.
-->
+The Flink community highly appreciates all sorts of contributions to
FlinkML.
+FlinkML offers people interested in machine learning to work on a highly
active open source project which makes scalable ML reality.
+The following document describes how to contribute to FlinkML.
+
* This will be replaced by the TOC
{:toc}
-Coming soon. In the meantime, check our list of [open issues on
JIRA](https://issues.apache.org/jira/browse/FLINK-1748?jql=component%20%3D%20%22Machine%20Learning%20Library%22%20AND%20project%20%3D%20FLINK%20AND%20resolution%20%3D%20Unresolved%20ORDER%20BY%20priority%20DESC)
+## Getting Started
+
+In order to get started first read Flink's [contribution
guide](http://flink.apache.org/how-to-contribute.html).
+Everything from this guide also applies to FlinkML.
+
+## Pick a Topic
+
+If you are looking for some new ideas, then you should check out the list
of [unresolved issues on
JIRA](https://issues.apache.org/jira/issues/?jql=component%20%3D%20%22Machine%20Learning%20Library%22%20AND%20project%20%3D%20FLINK%20AND%20resolution%20%3D%20Unresolved%20ORDER%20BY%20priority%20DESC).
+Once you decide to contribute to one of these issues, you should take
ownership of it and track your progress with this issue.
+That way, the other contributors know the state of the different issues
and redundant work is avoided.
+
+If you already know what you want to contribute to FlinkML all the better.
+It is still advisable to create a JIRA issue for your idea to tell the
Flink community what you want to do, though.
+
+## Testing
+
+New contributions should come with tests to verify the correct behavior of
the algorithm.
+The tests help to maintain the algorithm's correctness throughout code
changes, e.g. refactorings.
+
+We distinguish between unit tests, which are executed during maven's test
phase, and integration tests, which are executed during maven's verify phase.
+Maven automatically makes this distinction by using the following naming
rules:
+All test cases whose class name ends with a suffix fulfilling the regular
expression `(IT|Integration)(Test|Suite|Case)`, are considered integration
tests.
+The rest are considered unit tests and should only test behavior which is
local to the component under test.
+
+An integration test is a test which requires the full Flink system to be
started.
+In order to do that properly, all integration test cases have to mix in
the trait `FlinkTestBase`.
+This trait will set the right `ExecutionEnvironment` so that the test will
be executed on a special `FlinkMiniCluster` designated for testing purposes.
+Thus, an integration test could look the following:
+
+{% highlight scala %}
+class ExampleITSuite extends FlatSpec with FlinkTestBase {
+ behavior of "An example algorithm"
+
+ it should "do something" in {
+ ...
+ }
+}
+{% endhighlight %}
+
+The test style does not have to be `FlatSpec` but can be any other
scalatest `Suite` subclass.
+
+## Documentation
+
+When contributing new algorithms, it is required to add code comments
describing the functioning of the algorithm and its parameters with which the
user can control its behavior.
--- End diff --
functioning -> functionality
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