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From ewe...@apache.org
Subject kafka git commit: MINOR: Adding example to SMT documentation
Date Thu, 23 Mar 2017 06:05:36 GMT
Repository: kafka
Updated Branches:
  refs/heads/trunk 57278aa82 -> 95ef40dd3

MINOR: Adding example to SMT documentation

Author: Gwen Shapira <cshapi@gmail.com>

Reviewers: Ewen Cheslack-Postava <ewen@confluent.io>

Closes #2721 from gwenshap/improve_smt_docs

Project: http://git-wip-us.apache.org/repos/asf/kafka/repo
Commit: http://git-wip-us.apache.org/repos/asf/kafka/commit/95ef40dd
Tree: http://git-wip-us.apache.org/repos/asf/kafka/tree/95ef40dd
Diff: http://git-wip-us.apache.org/repos/asf/kafka/diff/95ef40dd

Branch: refs/heads/trunk
Commit: 95ef40dd31b6b0ee403413184ef974c6c051ddeb
Parents: 57278aa
Author: Gwen Shapira <cshapi@gmail.com>
Authored: Wed Mar 22 23:06:26 2017 -0700
Committer: Ewen Cheslack-Postava <me@ewencp.org>
Committed: Wed Mar 22 23:06:26 2017 -0700

 docs/connect.html | 68 +++++++++++++++++++++++++++++++++++++++++++++++++-
 docs/toc.html     |  6 +++++
 2 files changed, 73 insertions(+), 1 deletion(-)

diff --git a/docs/connect.html b/docs/connect.html
index d6b6f00..48c5139 100644
--- a/docs/connect.html
+++ b/docs/connect.html
@@ -104,7 +104,7 @@
     <h4><a id="connect_transforms" href="#connect_transforms">Transformations</a></h4>
-    Connectors can be configured with transformations to make lightweight message-at-a-time
modifications. They can be convenient for minor data massaging and routing changes.
+    Connectors can be configured with transformations to make lightweight message-at-a-time
modifications. They can be convenient for data massaging and event routing.
     A transformation chain can be specified in the connector configuration.
@@ -114,8 +114,74 @@
Configuration properties for the transformation</li>
+    <p>For example, lets take the built-in file source connector and use a transformation
to add a static field.</p>
+    <p>Throughout the example we'll use schemaless JSON data format. To use schemaless
format, we changed the following two lines in <code>connect-standalone.properties</code>
from true to false:</p>
+    <pre>
+        key.converter.schemas.enable
+        value.converter.schemas.enable
+    </pre>
+    The file source connector reads each line as a String. We will wrap each line in a Map
and then add a second field to identify the origin of the event. To do this, we use two transformations:
+    <ul>
+        <li><b>HoistField</b> to place the input line inside a Map</li>
+        <li><b>InsertField</b> to add the static field. In this example
we'll indicate that the record came from a file connector</li>
+    </ul>
+    After adding the transformations, <code>connect-file-source.properties</code>
file looks as following:
+    <pre>
+        name=local-file-source
+        connector.class=FileStreamSource
+        tasks.max=1
+        file=test.txt
+        topic=connect-test
+        transforms=MakeMap, InsertSource
+        transforms.MakeMap.type=org.apache.kafka.connect.transforms.HoistField$Value
+        transforms.MakeMap.field=line
+        transforms.InsertSource.type=org.apache.kafka.connect.transforms.InsertField$Value
+        transforms.InsertSource.static.field=data_source
+        transforms.InsertSource.static.value=test-file-source
+    </pre>
+    <p>All the lines starting with <code>transforms</code> were added for
the transformations. You can see the two transformations we created: "InsertSource" and "MakeMap"
are aliases that we chose to give the transformations. The transformation types are based
on the list of built-in transformations you can see below. Each transformation type has additional
configuration: HoistField requires a configuration called "field", which is the name of the
field in the map that will include the original String from the file. InsertField transformation
lets us specify the field name and the value that we are adding.</p>
+    When we ran the file source connector on my sample file without the transformations,
and then read them using <code>kafka-console-consumer.sh</code>, the results were:
+    <pre>
+        "foo"
+        "bar"
+        "hello world"
+   </pre>
+    We then create a new file connector, this time after adding the transformations to the
configuration file. This time, the results will be:
+    <pre>
+        {"line":"foo","data_source":"test-file-source"}
+        {"line":"bar","data_source":"test-file-source"}
+        {"line":"hello world","data_source":"test-file-source"}
+    </pre>
+    You can see that the lines we've read are now part of a JSON map, and there is an extra
field with the static value we specified. This is just one example of what you can do with
     Several widely-applicable data and routing transformations are included with Kafka Connect:
+    <ul>
+        <li>InsertField - Add a field using either static data or record metadata</li>
+        <li>ReplaceField - Filter or rename fields</li>
+        <li>MaskField - Replace field with valid null value for the type (0, empty
string, etc)</li>
+        <li>ValueToKey</li>
+        <li>HoistField - Wrap the entire event as a single field inside a Struct or
a Map</li>
+        <li>ExtractField - Extract a specific field from Struct and Map and include
only this field in results</li>
+        <li>SetSchemaMetadata - modify the schema name or version</li>
+        <li>TimestampRouter - Modify the topic of a record based on original topic
and timestamp. Useful when using a sink that needs to write to different tables or indexes
based on timestamps</li>
+        <li>RegexpRouter - modify the topic of a record based on original topic, replacement
string and a regular expression</li>
+    </ul>
+    Details on how to configure each transformation are listed below:
     <!--#include virtual="generated/connect_transforms.html" -->
     <h4><a id="connect_rest" href="#connect_rest">REST API</a></h4>

diff --git a/docs/toc.html b/docs/toc.html
index 787153d..935703b 100644
--- a/docs/toc.html
+++ b/docs/toc.html
@@ -130,6 +130,12 @@
                 <li><a href="#connect_overview">8.1 Overview</a></li>
                 <li><a href="#connect_user">8.2 User Guide</a></li>
+                <ul>
+                    <li><a href="#connect_running">Running Kafka Connect</a></li>
+                    <li><a href="#connect_configuring">Configuring Connectors</a></li>
+                    <li><a href="#connect_transforms">Transformations</a></li>
+                    <li><a href="#connect_rest">REST API</a></li>
+                </ul>
                 <li><a href="#connect_development">8.3 Connector Development

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