Schema Entities

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You can use Schema Registry to work with three types of schema entities:

Figure 4.2. Schema entities

The following table provides a more detailed description of the schema entities:

Table 4.1. Schema entity types

Entity Type	Description	Example
Schema group	A logical grouping of similar schemas. A Schema Group can be based on any criteria you have for managing schemas. Schema Groups can have multiple Schema Metadata definitions.	Group Name – truck-sensors-log Group Name – truck-sensors-kafka
Schema metadata	Metadata associated with a named schema. A metadata definition is applied to all the schema versions that are assigned to it. Key metadata elements include the following: Schema Name A unique name for each schema. Used as a key to look up schemas. Schema Type The format of the schema. Note: Avro is currently the only supported type. Compatibility Policy The compatibility rules that exist when the new schemas are registered. See Compatibility Policies for more information. Serializers/Deserializers A set of serializers and deserializers that you can upload to the registry and associate with schema metadata definitions.	Schema Name – truck_events_avro:v Schema Type – avro Compatibility Policy – SchemaCompatibility.BACKWARD
Schema version	The versioned schema associated a schema metadata definition.	{ "type" : "record", "namespace" : "hortonworks.hdp.refapp.trucking", "name" : "truckgeoevent", "fields" : [ { "name" : "eventTime" , "type" : "string" }, { "name" : "eventSource" , "type" : "string" }, { "name" : "truckId" , "type" : "int" }, { "name" : "driverId" , "type" : "int"}, { "name" : "driverName" , "type" : "string"}, { "name" : "routeId" , "type" : "int"}, { "name" : "route" , "type" : "string"}, { "name" : "eventType" , "type" : "string"}, { "name" : "longitude" , "type" : "double"}, { "name" : "latitude" , "type" : "double"}, { "name" : "correlationId" , "type" : "long"} ] }

Entity Type

Description

Example

Schema group

A logical grouping of similar schemas. A Schema Group can be based on any criteria you have for managing schemas.

Schema Groups can have multiple Schema Metadata definitions.

Group Name – truck-sensors-log
Group Name – truck-sensors-kafka

Schema metadata

Metadata associated with a named schema. A metadata definition is applied to all the schema versions that are assigned to it.

Key metadata elements include the following:

Schema Name
A unique name for each schema. Used as a key to look up schemas.
Schema Type
The format of the schema.
Note: Avro is currently the only supported type.
Compatibility Policy
The compatibility rules that exist when the new schemas are registered. See Compatibility Policies for more information.
Serializers/Deserializers
A set of serializers and deserializers that you can upload to the registry and associate with schema metadata definitions.

Schema Name – truck_events_avro:v
Schema Type – avro
Compatibility Policy – SchemaCompatibility.BACKWARD

Schema version

The versioned schema associated a schema metadata definition.

{   
  "type" : "record",   
  "namespace" : "hortonworks.hdp.refapp.trucking",   
  "name" : "truckgeoevent",   
  "fields" : [     
    { "name" : "eventTime" , "type" : "string" },     
    { "name" : "eventSource" , "type" : "string" },      
    { "name" : "truckId" , "type" : "int" },      
    { "name" : "driverId" , "type" : "int"},      
    { "name" : "driverName" , "type" : "string"},      
    { "name" : "routeId" , "type" : "int"},      
    { "name" : "route" , "type" : "string"},      
    { "name" : "eventType" , "type" : "string"},      
    { "name" : "longitude" , "type" : "double"},      
    { "name" : "latitude" , "type" : "double"},     
    { "name" : "correlationId" , "type" : "long"}   
  ]
}

​Schema Entities

Schema Entities