[GitHub] [calcite] XuMingmin commented on a change in pull request #1127: [CALCITE-2913] Adapter for Apache Kafka

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XuMingmin commented on a change in pull request #1127: [CALCITE-2913] Adapter for Apache Kafka
URL: https://github.com/apache/calcite/pull/1127#discussion_r284358866
 
 

 ##########
 File path: site/_docs/kafka_adapter.md
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+---
+layout: docs
+title: Kafka adapter
+permalink: /docs/kafka_adapter.html
+---
+<!--
+{% comment %}
+Licensed to the Apache Software Foundation (ASF) under one or more
+contributor license agreements.  See the NOTICE file distributed with
+this work for additional information 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.
+{% endcomment %}
+-->
+  
+**Note**:
+
+KafkaAdapter is an experimental feature, changes in public API and usage are expected.
+
+For instructions on downloading and building Calcite, start with the[tutorial]({{ site.baseurl }}/docs/tutorial.html).
+
+The Kafka adapter exposes an Apache Kafka topic as a STREAM table, so it can be queried using
+[Calcite Stream SQL]({{ site.baseurl }}/docs/stream.html). Note that the adapter will not attempt to scan all topics,
+instead users need to configure tables manually, one Kafka stream table is mapping to one Kafka topic.
+
+A basic example of a model file is given below:
+
+{% highlight json %}
+{
+  "version": "1.0",
+  "defaultSchema": "KAFKA",
+  "schemas": [
+    {
+      "name": "KAFKA",
+      "tables": [
+        {
+          "name": "TABLE_NAME",
+          "type": "custom",
+          "factory": "org.apache.calcite.adapter.kafka.KafkaTableFactory",
+          "row.converter": "com.example.CustKafkaRowConverter",
+          "operand": {
+            "bootstrap.servers": "host1:port,host2:port",
+            "topic.name": "kafka.topic.name",
+            "consumer.params": {
+              "key.deserializer": "org.apache.kafka.common.serialization.ByteArrayDeserializer",
+              "value.deserializer": "org.apache.kafka.common.serialization.ByteArrayDeserializer"
+            }
+          }
+        }
+      ]
+    }
+  ]
+}
+{% endhighlight %}
+
+Note that:
+
+1. As Kafka message is schemaless, a [KafkaRowConverter]({{ site.apiRoot }}/org/apache/calcite/adapter/kafka/KafkaRowConverter.html)
+ is required to specify row schema explicitly(with parameter `row.converter`), and
+ how to decode Kafka message to Calcite row. [KafkaRowConverterImpl]({{ site.apiRoot }}/org/apache/calcite/adapter/kafka/KafkaRowConverterImpl.html)
+ is used if not provided;
+
+2. More consumer settings can be added in parameter `consumer.paras`;
 
 Review comment:
   yes, let me update it.

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