See this page for more details about Pail:
http://deals.manningpublications.com/pail.pdf

|+ mtitek-pail-object-samples |+ src |+ main |+ java |+ mtitek.pail.object.samples |+ Payload.java |+ PailStructurePayload.java |+ PailPayload.java |+ pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>mtitek.pail.object.samples</groupId> <artifactId>mtitek-pail-object-samples</artifactId> <version>1.0.0-SNAPSHOT</version> <dependencies> <dependency> <groupId>org.apache.hadoop</groupId> <artifactId>hadoop-common</artifactId> <version>2.7.3</version> </dependency> <dependency> <groupId>com.backtype</groupId> <artifactId>dfs-datastores</artifactId> <version>1.3.6</version> </dependency> </dependencies> </project>

A simple POJO java class that will be used as an example to show how to write/read Objects to/from pail.

► src/main/java/mtitek/pail/object/samples/Payload.java

package mtitek.pail.object.samples; public class Payload implements java.io.Serializable { private static final long serialVersionUID = -4058347141743162269L; private Integer field1; public Integer getField1() { return field1; } public void setField1(Integer field1) { this.field1 = field1; } @Override public String toString() { return "Payload [field1=" + field1 + "]"; } }

This java class is an implementation of the PailStructure interface that the Pail API will use to serialize/deserialize the payload objects.

► src/main/java/mtitek/pail/object/samples/PailStructurePayload.java

package mtitek.pail.object.samples; import java.util.Collections; import java.util.List; import org.apache.commons.lang.SerializationUtils; import com.backtype.hadoop.pail.PailStructure; public class PailStructurePayload implements PailStructure<Payload> { private static final long serialVersionUID = 4759079091041385329L; public byte[] serialize(Payload object) { return SerializationUtils.serialize(object); } public Payload deserialize(byte[] serialized) { return (Payload) SerializationUtils.deserialize(serialized); } public Class<Payload> getType() { return Payload.class; } public boolean isValidTarget(String... dirs) { return true; } public List<String> getTarget(Payload object) { return Collections.emptyList(); } }

This java class shows how to use the Pail API to write/read Objects to/from pail.

► src/main/java/mtitek/pail/object/samples/PailPayload.java

package mtitek.pail.object.samples; import java.io.IOException; import java.util.Random; import org.apache.hadoop.fs.Path; import com.backtype.hadoop.pail.Pail; public class PailPayload { private static final String PAIL_PATH = "/tmp/pail-test/pail-payload"; public static void main(String[] args) throws IOException { @SuppressWarnings("unchecked") final Pail<Payload> pail = Pail.create(PailString.PAIL_PATH, new PailStructurePayload(), false); writePayloads(pail); readPayload(pail); } private static void writePayloads(final Pail<Payload> pail) throws IOException { final Pail<Payload>.TypedRecordOutputStream typedRecordOutputStream = pail.openWrite(); final Payload payload = new Payload(); payload.setField1(new Random().nextInt()); typedRecordOutputStream.writeObject(payload); typedRecordOutputStream.close(); } private static void readPayload(final Pail<Payload> pail) throws IOException { for (final Payload payload : pail) { System.out.println(payload); } } }