Add serialization trait.

build.sbt

diff --git a/build.sbt b/build.sbt
index 1f27989..21f4f87 100644
--- a/build.sbt
+++ b/build.sbt
@@ -27,16 +27,13 @@
   )
 )
 
-lazy val commons = (project in file("commons.v2")).settings (
-  common
-)
+lazy val commons = (project in file("commons.v2")).settings(common)
 
-lazy val bsp = (project in file("bsp")).settings (
-  common
-)
+lazy val bsp = (project in file("bsp")).settings(common)
 
-lazy val membership = (project in file("membership")).settings (
-  common
-) .dependsOn(commons)
+lazy val io = (project in file("io")).settings(common)
+
+lazy val membership = (project in file("membership")).settings(common).
+  dependsOn(commons)
 
 lazy val core = (project in file(".")).aggregate(commons, bsp, membership)

io/build.sbt

diff --git a/io/build.sbt b/io/build.sbt
new file mode 100644
index 0000000..0f1604e
--- /dev/null
+++ b/io/build.sbt
@@ -0,0 +1,18 @@
+/**
+ * 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.
+ */
+name := "io"

io/src/main/scala/org/apache/hama/io/serialization.scala

diff --git a/io/src/main/scala/org/apache/hama/io/serialization.scala b/io/src/main/scala/org/apache/hama/io/serialization.scala
new file mode 100644
index 0000000..6426b14
--- /dev/null
+++ b/io/src/main/scala/org/apache/hama/io/serialization.scala
@@ -0,0 +1,56 @@
+/**
+ * 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.hama.io
+
+import java.io.DataInput
+import java.io.DataOutput
+import scala.util.Failure
+import scala.util.Success
+import scala.util.Try
+
+trait serialization[T] {
+
+  def read(input: DataInput, clazz: Class[T]): T
+
+  def write(value: T): Either[Throwable, Array[Byte]]
+
+}
+object serialization {
+
+  def apply[T](implicit instance: T) = instance
+
+  implicit val int = new serialization[Int] {
+
+    override def read(input: DataInput, clazz: Class[Int]): Int = 
+      input.readInt
+    
+    override def write(value: Int): Either[Throwable, Array[Byte]] = Try {
+      val byteStream = new ByteArrayOutputStream
+      val out = new DataOutputStream(byteSteram)
+      out.writeInt(value)
+      (out, byteStream)
+    } match {
+      case Failure(ex) => Left(ex)
+      case Success((out, stream)) => 
+        try {} finally { out.close }
+        Right(stream.toByteArray) 
+    }
+
+  }
+
+}