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From twalthr <...@git.apache.org>
Subject [GitHub] flink pull request #6264: [FLINK-8558] [table] Add unified format interfaces...
Date Tue, 10 Jul 2018 14:26:04 GMT
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.


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