AvroIDL can handle imports, but it generates classes. The Avro API's for this can be used to generate Schemas without making objects if you wish.
The Avro schema compiler (*.avsc, *.avpr) does not support imports, it is a feature requested by many but not contributed by anyone. You may be interested in the code-gen capabilities of Avro, which has a Velocity templating engine to create Java classes based on schemas. This can be customized to generate classes in custom ways. However, if you are using Avro to serialize objects that have pre-existing classes, the Reflect API or an enhancement of it may be more suitable. More information on your use case may help to point you in the right direction. -Scott On 7/14/11 6:43 PM, "Peter Wolf" <[email protected]<mailto:[email protected]>> wrote: Many thanks Scott, I am looking for the equivalent of #include or import. I want to make a complicated schema with many record types, but manage it in separate strings. In my application, I am using AVRO to serialize a tree of connected Java objects. The record types mirror Java classes. The schema descriptions live in the different Java classes, and reference each other. My current code looks like this... public class Foo { static String schemaDescription = "{" + " \"namespace\": \"foo\", " + " \"name\": \"Foo\", " + " \"type\": \"record\", " + " \"fields\": [ " + " {\"name\": \"notes\", \"type\": \"string\" }, " + " {\"name\": \"timestamp\", \"type\": \"string\" }, " + " {\"name\": \"bah\", \"type\": " + Bah.schemaDescription + " }," + " {\"name\": \"zot\", \"type\": " + Zot.schemaDescription + " }" + " ]" + "}"; static Schema schema = Schema.parse(schemaDescription); So, I am referencing by copying the schemaDescriptions. The top level schemaDescription strings therefore get really big. Is there already a clean coding Pattern for doing this-- I can't be the first. Is there a document describing best practices? Thanks P On 7/14/11 7:02 PM, Scott Carey wrote: The name and namespace is part of any named schema (Type.RECORD, Type.FIXED, Type.ENUM). We don't currently have an API to search a schema for subschemas that match names. It would be useful, you might want to create a JIRA ticket explaining your use case. So it would be a little more complex. Schema schema = Schema.parse(schemaDescription); Schema.Type type = schema.getType(); switch (type) { case RECORD: String name = schema.getName(); String namespace = schema.getNamespace(); List<Field> fields = schema.getFields(); } etc. In general, I have created SpecificRecord objects from schemas using the specific compiler (and the ant task or maven plugin) and then within those generated classes there is a static SCHEMA variable to reference. Avro IDL is alo an easier way to define related schemas. Currently there are only build tools that generate code from these, though there are APIs to extract schemas. -Scott On 7/13/11 10:43 AM, "Peter Wolf" <[email protected]<mailto:[email protected]>> wrote: Hello, this a dumb question, but I can not find the answer in the docs I want to have a complicated schema with lots of Records referencing other Records. Like this... { "namespace": "com.foobah", "name": "Bah", "type": "record", "fields": [ {"name": "value", "type": "int"} ] } { "namespace": "com.foobah", "name": "Foo", "type": "record", "fields": [ {"name": "bah", "type": "Bah"} ] } Using the Java API, how do I reference types within a schema? Let's say I want to make a Foo object, I want to do something like this... Schema schema = Schema.parse(schemaDescription); >>> Schema foo = schema.getSchema("com.foobah.Foo"); <<< GenericData o = new GenericData( foo ); Many thanks in advance Peter
