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/*
 * 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.kafka.connect.data;

import java.util.List;
import java.util.Locale;
import java.util.Map;

/**
 * 

* Definition of an abstract data type. Data types can be primitive types (integer types, floating point types, * boolean, strings, and bytes) or complex types (typed arrays, maps with one key schema and value schema, * and structs that have a fixed set of field names each with an associated value schema). Any type can be specified * as optional, allowing it to be omitted (resulting in null values when it is missing) and can specify a default * value. *

*

* All schemas may have some associated metadata: a name, version, and documentation. These are all considered part * of the schema itself and included when comparing schemas. Besides adding important metadata, these fields enable * the specification of logical types that specify additional constraints and semantics (e.g. UNIX timestamps are * just an int64, but the user needs the know about the additional semantics to interpret it properly). *

*

* Schemas can be created directly, but in most cases using {@link SchemaBuilder} will be simpler. *

*/ public interface Schema { /** * The type of a schema. These only include the core types; logical types must be determined by checking the schema name. */ enum Type { /** * 8-bit signed integer * * Note that if you have an unsigned 8-bit data source, {@link Type#INT16} will be required to safely capture all valid values */ INT8, /** * 16-bit signed integer * * Note that if you have an unsigned 16-bit data source, {@link Type#INT32} will be required to safely capture all valid values */ INT16, /** * 32-bit signed integer * * Note that if you have an unsigned 32-bit data source, {@link Type#INT64} will be required to safely capture all valid values */ INT32, /** * 64-bit signed integer * * Note that if you have an unsigned 64-bit data source, the {@link Decimal} logical type (encoded as {@link Type#BYTES}) * will be required to safely capture all valid values */ INT64, /** * 32-bit IEEE 754 floating point number */ FLOAT32, /** * 64-bit IEEE 754 floating point number */ FLOAT64, /** * Boolean value (true or false) */ BOOLEAN, /** * Character string that supports all Unicode characters. * * Note that this does not imply any specific encoding (e.g. UTF-8) as this is an in-memory representation. */ STRING, /** * Sequence of unsigned 8-bit bytes */ BYTES, /** * An ordered sequence of elements, each of which shares the same type. */ ARRAY, /** * A mapping from keys to values. Both keys and values can be arbitrarily complex types, including complex types * such as {@link Struct}. */ MAP, /** * A structured record containing a set of named fields, each field using a fixed, independent {@link Schema}. */ STRUCT; private String name; Type() { this.name = this.name().toLowerCase(Locale.ROOT); } public String getName() { return name; } public boolean isPrimitive() { switch (this) { case INT8: case INT16: case INT32: case INT64: case FLOAT32: case FLOAT64: case BOOLEAN: case STRING: case BYTES: return true; } return false; } } Schema INT8_SCHEMA = SchemaBuilder.int8().build(); Schema INT16_SCHEMA = SchemaBuilder.int16().build(); Schema INT32_SCHEMA = SchemaBuilder.int32().build(); Schema INT64_SCHEMA = SchemaBuilder.int64().build(); Schema FLOAT32_SCHEMA = SchemaBuilder.float32().build(); Schema FLOAT64_SCHEMA = SchemaBuilder.float64().build(); Schema BOOLEAN_SCHEMA = SchemaBuilder.bool().build(); Schema STRING_SCHEMA = SchemaBuilder.string().build(); Schema BYTES_SCHEMA = SchemaBuilder.bytes().build(); Schema OPTIONAL_INT8_SCHEMA = SchemaBuilder.int8().optional().build(); Schema OPTIONAL_INT16_SCHEMA = SchemaBuilder.int16().optional().build(); Schema OPTIONAL_INT32_SCHEMA = SchemaBuilder.int32().optional().build(); Schema OPTIONAL_INT64_SCHEMA = SchemaBuilder.int64().optional().build(); Schema OPTIONAL_FLOAT32_SCHEMA = SchemaBuilder.float32().optional().build(); Schema OPTIONAL_FLOAT64_SCHEMA = SchemaBuilder.float64().optional().build(); Schema OPTIONAL_BOOLEAN_SCHEMA = SchemaBuilder.bool().optional().build(); Schema OPTIONAL_STRING_SCHEMA = SchemaBuilder.string().optional().build(); Schema OPTIONAL_BYTES_SCHEMA = SchemaBuilder.bytes().optional().build(); /** * @return the type of this schema */ Type type(); /** * @return true if this field is optional, false otherwise */ boolean isOptional(); /** * @return the default value for this schema */ Object defaultValue(); /** * @return the name of this schema */ String name(); /** * Get the optional version of the schema. If a version is included, newer versions *must* be larger than older ones. * @return the version of this schema */ Integer version(); /** * @return the documentation for this schema */ String doc(); /** * Get a map of schema parameters. * @return Map containing parameters for this schema, or null if there are no parameters */ Map parameters(); /** * Get the key schema for this map schema. Throws a DataException if this schema is not a map. * @return the key schema */ Schema keySchema(); /** * Get the value schema for this map or array schema. Throws a DataException if this schema is not a map or array. * @return the value schema */ Schema valueSchema(); /** * Get the list of fields for this Schema. Throws a DataException if this schema is not a struct. * @return the list of fields for this Schema */ List fields(); /** * Get a field for this Schema by name. Throws a DataException if this schema is not a struct. * @param fieldName the name of the field to look up * @return the Field object for the specified field, or null if there is no field with the given name */ Field field(String fieldName); /** * Return a concrete instance of the {@link Schema} * @return the {@link Schema} */ Schema schema(); }




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