Puzzled about Avro serialization

[David Rosenstrauch <da...@darose.net>]

Hi.  Newbie here, kicking the tires on Avro.

Although I read through the docs pretty carefully, I think I'm somehow 
missing some key point about how Avro serialization works.  I tried 
testing it out with the following code, and schema, but I'm not getting 
any serialized output.  Anyone know what I'm doing wrong?

Thanks,

DR

--------

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;

import junit.framework.TestCase;

import org.apache.avro.Schema;
import org.apache.avro.io.JsonEncoder;
import org.apache.avro.specific.SpecificDatumWriter;

public class TestAvroSerialization extends TestCase {

	protected void setUp() {
		schemaFile = new File("test_data/avro/SimpleRecord.avsc");
	}

	public void testParseSchema() throws IOException {
		doParseSchema();
	}

	public void testSerializeRecord() throws IOException {
		Schema recordSchema = doParseSchema();
		System.out.println(recordSchema.toString(true));
		SpecificDatumWriter<SimpleRecord> writer = new 
SpecificDatumWriter<SimpleRecord>(recordSchema);
		ByteArrayOutputStream out = new ByteArrayOutputStream();
		JsonEncoder encoder = new JsonEncoder(recordSchema, out);
		SimpleRecord record = new SimpleRecord(recordSchema);
		writer.write(record, encoder);
		System.out.println(out.toString() + "<eof>");
		fail("todo");
	}

	public void testDeserializeRecord() throws IOException {
		Schema recordSchema = doParseSchema();
		fail("todo");
	}


	private Schema doParseSchema() throws IOException {
		Schema recordSchema = Schema.parse(schemaFile);
		return recordSchema;
	}

	private File schemaFile;

}

--------

import org.apache.avro.Schema;
import org.apache.avro.specific.SpecificRecordBase;

public class SimpleRecord extends SpecificRecordBase {

	private Schema schema;

	public SimpleRecord(Schema schema) {
		this.schema = schema;
	}

	public Object get(int i) {
		if (i != 0) {
			throw new IllegalArgumentException();
		}
		return val;
	}

	public void put(int i, Object val) {
		if (i != 0) {
			throw new IllegalArgumentException();
		}
		if (!(val instanceof Integer)) {
			throw new IllegalArgumentException();
		}
		Integer intVal = (Integer)val;
		this.val = intVal;
	}

	public Schema getSchema() {
		return schema;
	}

	private int val = 1;
}

--------

test_data/avro/SimpleRecord.avsc
--------
{
	"type": "record",
	"name": "SimpleRecord",
	"fields" : [
		{"name": "val", "type": "int"}
	]
}

--------

Output
--------
{
   "type" : "record",
   "name" : "SimpleRecord",
   "fields" : [ {
     "name" : "val",
     "type" : "int"
   } ]
}
<eof>

Re: Puzzled about Avro serialization

[Philip Zeyliger <ph...@cloudera.com>]

Take a look also at
lang/java/src/java/org/apache/avro/tool/JsonToBinaryFragmentTool.java
if you just want to play with fragments of avro-encoded data.

-- Philip

On Wed, Jul 7, 2010 at 12:44 PM, David Rosenstrauch <da...@darose.net> wrote:
> On 07/07/2010 03:22 PM, David Rosenstrauch wrote:
>>
>> Hi.  Newbie here, kicking the tires on Avro.
>>
>> Although I read through the docs pretty carefully, I think I'm somehow
>> missing some key point about how Avro serialization works. I tried
>> testing it out with the following code, and schema, but I'm not getting
>> any serialized output. Anyone know what I'm doing wrong?
>>
>> Thanks,
>>
>> DR
>
> Doh!  Posted too soon.
>
> Googling for "avro serialization example" turned up a blog post
> (http://blog.voidsearch.com/bigdata/apache-avro-in-practice/) with the magic
> incantation:  encoder.flush();
>
> Sorry for the noise.
>
> DR
>

Re: Puzzled about Avro serialization

[David Rosenstrauch <da...@darose.net>]

On 07/07/2010 03:22 PM, David Rosenstrauch wrote:
> Hi.  Newbie here, kicking the tires on Avro.
>
> Although I read through the docs pretty carefully, I think I'm somehow
> missing some key point about how Avro serialization works. I tried
> testing it out with the following code, and schema, but I'm not getting
> any serialized output. Anyone know what I'm doing wrong?
>
> Thanks,
>
> DR

Doh!  Posted too soon.

Googling for "avro serialization example" turned up a blog post 
(http://blog.voidsearch.com/bigdata/apache-avro-in-practice/) with the 
magic incantation:  encoder.flush();

Sorry for the noise.

DR