Simplestringserde (apache#19)

* Create pulsar-functions module (#1)

* Create pulsar-functions module

* rename `sdk` package to `api`

* Added the first cut of the Java interface for Pulsar functions (#2)

* Added a simple String based serde

pulsar-functions/run-examples.sh

@@ -1 +1 @@
-CLASSPATH=`pwd`/api-examples/target/pulsar-functions-api-examples.jar bin/pulsar-functions functions run --function-config conf/example.yml --sink-topic persistent://sample/standalone/ns1/test_result --source-topic persistent://sample/standalone/ns1/test_src --function-classpath `pwd`/api-examples/target/pulsar-functions-api-examples.jar
+CLASSPATH=`pwd`/api-examples/target/pulsar-functions-api-examples.jar bin/pulsar-functions functions run --function-config conf/example.yml --sink-topic persistent://sample/standalone/ns1/test_result --source-topic persistent://sample/standalone/ns1/test_src --serde-classname org.apache.pulsar.functions.runtime.container.SimpleStringSerDe --function-classpath `pwd`/api-examples/target/pulsar-functions-api-examples.jar

pulsar-functions/runtime/src/main/java/org/apache/pulsar/functions/runtime/container/SimpleStringSerDe.java

@@ -0,0 +1,44 @@
+/**
+ * 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.pulsar.functions.runtime.container;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.*;
+
+/**
+ * A simple Serde that treats the bytes as Java String
+ */
+public class SimpleStringSerDe implements SerDe {
+    private static final Logger log = LoggerFactory.getLogger(SimpleStringSerDe.class);
+
+    public SimpleStringSerDe() { }
+
+    @Override
+    public byte[] serialize(Object resultValue) {
+        String string = (String) resultValue;
+        return string.getBytes();
+    }
+
+    @Override
+    public Object deserialize(byte[] data) {
+        return new String(data);
+    }
+}