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https://issues.apache.org/jira/browse/FLINK-8558?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16538680#comment-16538680
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ASF GitHub Bot commented on FLINK-8558:
---------------------------------------
Github user twalthr commented on a diff in the pull request:
https://github.com/apache/flink/pull/6264#discussion_r201363632
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/formats/TableFormatFactory.scala
---
@@ -0,0 +1,85 @@
+/*
+ * 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.
+ */
+
+package org.apache.flink.table.formats
+
+import java.util
+
+import org.apache.flink.api.common.serialization.{DeserializationSchema,
SerializationSchema}
+
+/**
+ * A factory to create different table format instances. This factory is
used with Java's Service
+ * Provider Interfaces (SPI) for discovering. A factory is called with a
set of normalized
+ * properties that describe the desired format. The factory allows for
matching to the given set of
+ * properties. See also [[SerializationSchemaFactory]] and
[[DeserializationSchemaFactory]] for
+ * creating configured instances of format classes accordingly.
+ *
+ * Classes that implement this interface need to be added to the
+ * "META_INF/services/org.apache.flink.table.formats.TableFormatFactory'
file of a JAR file in
+ * the current classpath to be found.
+ *
+ * @tparam T record type that the format produces or consumes
+ */
+trait TableFormatFactory[T] {
+
+ /**
+ * Specifies the context that this factory has been implemented for.
The framework guarantees
+ * to only use the factory if the specified set of properties and
values are met.
+ *
+ * Typical properties might be:
+ * - format.type
+ * - format.version
+ *
+ * Specified property versions allow the framework to provide backwards
compatible properties
+ * in case of string format changes:
+ * - format.property-version
+ *
+ * An empty context means that the factory matches for all requests.
+ */
+ def requiredContext(): util.Map[String, String]
--- End diff --
Context defines the "context" in which the factory will be activated.
> Add unified format interfaces and format discovery
> --------------------------------------------------
>
> Key: FLINK-8558
> URL: https://issues.apache.org/jira/browse/FLINK-8558
> Project: Flink
> Issue Type: New Feature
> Components: Streaming Connectors
> Reporter: Timo Walther
> Assignee: Timo Walther
> Priority: Major
> Labels: pull-request-available
>
> In the last release, we introduced a new module {{flink-formats}}. Currently
> only {{flink-avro}} is located there but we will add more formats such as
> {{flink-json}}, {{flink-protobuf}}, and so on. For better separation of
> concerns we want decouple connectors from formats: e.g., remove
> {{KafkaAvroTableSource}} and {{KafkaJsonTableSource}}.
> A newly introduced {{FormatFactory}} will use Java service loaders to
> discovery available formats in the classpath (similar to how file systems are
> discovered now). A {{Format}} will provide a method for converting {{byte[]}}
> to target record type.
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