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https://issues.apache.org/jira/browse/FLINK-9947?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16563749#comment-16563749
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ASF GitHub Bot commented on FLINK-9947:
---------------------------------------
fhueske commented on a change in pull request #6456: [FLINK-9947] [docs]
Document unified table sources/sinks/formats
URL: https://github.com/apache/flink/pull/6456#discussion_r206540657
##########
File path: docs/dev/table/connect.md
##########
@@ -0,0 +1,1033 @@
+---
+title: "Connect to External Systems"
+nav-parent_id: tableapi
+nav-pos: 19
+---
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements. See the NOTICE file
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+regarding copyright ownership. The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License. You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied. See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+Flink's Table API & SQL programs can be connected to other external systems
for reading and writing both batch and streaming tables. A table source
provides access to data which is stored in external systems (such as a
database, key-value store, message queue, or file system). A table sink emits a
table to an external storage system. Depending on the type of source and sink,
they support different formats such as CSV, Parquet, or ORC.
+
+This page describes how to declare built-in table sources and/or table sinks
and register them in Flink. After a source, sink, or both have been registered,
they can be accessed by Table API & SQL queries.
+
+<span class="label label-danger">Attention</span> If you want to implement
your own *custom* table source or sink, have a look at the [user-defined
sources & sinks page](sourceSinks.html).
+
+* This will be replaced by the TOC
+{:toc}
+
+Dependencies
+------------
+
+The following table list all available connectors and formats. Their mutual
compatibility is tagged in the corresponding sections for [table
connectors](connect.html#table-connectors) and [table
formats](connect.html#table-formats). The following table provides dependency
information for both projects using a build automation tool (such as Maven or
SBT) and SQL Client with SQL JAR bundles.
+
+{% if site.is_stable %}
+
+### Connectors
+
+| Name | Version | Maven dependency | SQL
Client JAR |
+| :---------------- | :------------ | :--------------------------- |
:----------------------|
+| Filesystem | | Built-in | Built-in
|
+| Apache Kafka | 0.8 | `flink-connector-kafka-0.8` | Not
available |
+| Apache Kafka | 0.9 | `flink-connector-kafka-0.9` |
[Download](http://central.maven.org/maven2/org/apache/flink/flink-connector-kafka-0.9{{site.scala_version_suffix}}/{{site.version}}/flink-connector-kafka-0.9{{site.scala_version_suffix}}-{{site.version}}-sql-jar.jar)
|
+| Apache Kafka | 0.10 | `flink-connector-kafka-0.10` |
[Download](http://central.maven.org/maven2/org/apache/flink/flink-connector-kafka-0.10{{site.scala_version_suffix}}/{{site.version}}/flink-connector-kafka-0.10{{site.scala_version_suffix}}-{{site.version}}-sql-jar.jar)
|
+| Apache Kafka | 0.11 | `flink-connector-kafka-0.11` |
[Download](http://central.maven.org/maven2/org/apache/flink/flink-connector-kafka-0.11{{site.scala_version_suffix}}/{{site.version}}/flink-connector-kafka-0.11{{site.scala_version_suffix}}-{{site.version}}-sql-jar.jar)
|
+
+### Formats
+
+| Name | Maven dependency | SQL Client JAR |
+| :---------------- | :--------------------------- | :--------------------- |
+| CSV | Built-in | Built-in |
+| JSON | `flink-json` |
[Download](http://central.maven.org/maven2/org/apache/flink/flink-json/{{site.version}}/flink-json-{{site.version}}-sql-jar.jar)
|
+| Apache Avro | `flink-avro` |
[Download](http://central.maven.org/maven2/org/apache/flink/flink-avro/{{site.version}}/flink-avro-{{site.version}}-sql-jar.jar)
|
+
+{% else %}
+
+This table is only available for stable releases.
+
+{% endif %}
+
+{% top %}
+
+Overview
+--------
+
+Beginning from Flink 1.6, the declaration of a connection to an external
system is separated from the actual implementation. Connections can be
specified either
+
+- **programmatically** using a `Descriptor` under
`org.apache.flink.table.descriptors` for Table & SQL API
+- or **declaratively** via [YAML configuration files](http://yaml.org/) for
the SQL Client.
+
+This allows not only for better unification of APIs and SQL Client but also
for better extensibility in case of [custom implementations](sourceSinks.html)
without changing the declaration.
+
+Similar to a SQL `CREATE TABLE` statement, one can define the name of the
table, the final schema of the table, connector, and a data format upfront for
connecting to an external system. Additionally, the table's type (source, sink,
or both) and an update mode for streaming queries can be specified:
+
+<div class="codetabs" markdown="1">
+<div data-lang="Java/Scala" markdown="1">
+{% highlight java %}
+tableEnvironment
+ .connect(...)
+ .withFormat(...)
+ .withSchema(...)
+ .inAppendMode()
+ .registerTableSource(...)
+{% endhighlight %}
+</div>
+
+<div data-lang="YAML" markdown="1">
+{% highlight yaml %}
+name: MyTable
+type: source
+update-mode: append
+schema: ...
+format: ...
+connector: ...
+{% endhighlight %}
+</div>
+</div>
+
+The subsequent sections will cover each definition part
([schema](connect.html#table-schema),
[connector](connect.html#table-connectors),
[format](connect.html#table-formats), and [update
mode](connect.html#update-modes)) in more detail.
Review comment:
I think it would be good to explain the overall responsibilities and
dependencies of the descriptors before describing them in detail.
* Connector: defines all properties to connect to a data store as source or
sink
* Format: defines the format of the data in the storage system. Can be CSV,
Avro, Parquet but also the schema of a database table.
* TableSchema: defines the schema of a table as it is exposed to SQL
queries. Table schema fields can be linked to format fields or derived such as
time attributes.
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> Document unified table sources/sinks/formats
> --------------------------------------------
>
> Key: FLINK-9947
> URL: https://issues.apache.org/jira/browse/FLINK-9947
> Project: Flink
> Issue Type: Improvement
> Components: Documentation, Table API & SQL
> Reporter: Timo Walther
> Assignee: Timo Walther
> Priority: Major
> Labels: pull-request-available
>
> The recent unification of table sources/sinks/formats needs documentation. I
> propose a new page that explains the built-in sources, sinks, and formats as
> well as a page for customization of public interfaces.
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