Adds (de)serialization of DataPoints to byte array.

src/main/java/com/iobeam/api/resource/DataPoint.java

@@ -3,6 +3,7 @@
 import org.json.JSONObject;
 
 import java.io.Serializable;
+import java.nio.ByteBuffer;
 import java.text.ParseException;
 import java.util.ArrayList;
 import java.util.List;
@@ -16,6 +17,14 @@ public class DataPoint implements Serializable {
     private static final String KEY_TIME = "time";
     private static final String KEY_VALUE = "value";
 
+    public static final byte TYPE_LONG = 0x0;
+    public static final byte TYPE_DOUBLE = TYPE_LONG + 1;
+    public static final byte TYPE_STRING = TYPE_DOUBLE + 1;
+    /* Byte array format, all start with [time (8)][type (1)] (9 bytes), followed by:
+        - for int/long/float/double:     [value (8)] (17 total bytes)
+        - for strings:                   [len (4)][value (X)] (13 + X total bytes, X = len of str)
+     */
+
     private final long time;
     private final Object data;
 
@@ -162,6 +171,62 @@ public JSONObject toJson() {
         return ret;
     }
 
+    public static DataPoint fromByteArray(byte[] array) {
+        ByteBuffer buf = ByteBuffer.wrap(array);
+        long timestamp = buf.getLong();
+        byte type = buf.get();
+        if (type == TYPE_LONG) {
+            return new DataPoint(timestamp, buf.getLong());
+        } else if (type == TYPE_DOUBLE) {
+            return new DataPoint(timestamp, buf.getDouble());
+        } else {
+            int len = buf.getInt();
+            byte[] bytes = new byte[len];
+            buf.get(bytes, 0, len);
+            return new DataPoint(timestamp, new String(bytes));
+        }
+    }
+
+    /**
+     * Returns the byte array representation of this data point. Byte array format are as follows:
+     *
+     * Starts with 8 bytes for time and 1 byte for type for a total of 9 bytes. Then, based on value
+     * type, it does the following:
+     * - int/long/float/double: 8 bytes for the value, for 17 total bytes.
+     * - strings: 4 bytes for string length, then X bytes for string for a total of 13 + X bytes.
+     *
+     * @return Byte array representation
+     */
+    public byte[] toByteArray() {
+        int arrSize = 1 + Long.BYTES;  // first byte specifies type of data
+        byte type;
+        if (data instanceof Long) {
+            arrSize += Long.BYTES;
+            type = TYPE_LONG;
+        } else if (data instanceof Double) {
+            arrSize += Double.BYTES;
+            type = TYPE_DOUBLE;
+        } else {
+            arrSize += Integer.BYTES + ((String) data).length();
+            type = TYPE_STRING;
+        }
+
+        ByteBuffer buf = ByteBuffer.allocate(arrSize);
+        buf.putLong(time);
+        buf.put(type);
+        if (type == TYPE_LONG) {
+            buf.putLong((Long) data);
+        } else if (type == TYPE_DOUBLE) {
+            buf.putDouble((Double) data);
+        } else {
+            String temp = (String) data;
+            buf.putInt(temp.length());
+            buf.put(temp.getBytes());
+        }
+        buf.flip();
+        return buf.array();
+    }
+
     @Override
     public int hashCode() {
         return (int) this.time;

src/test/java/com/iobeam/api/resource/DataPointTest.java

@@ -1,112 +1,139 @@
-package com.iobeam.api.resource;
-
-import org.json.JSONObject;
-import org.junit.Test;
-
-import java.util.List;
-
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
-
-public class DataPointTest {
-
-    private static final String jsonDataPoint = "{\n"
-                                                + "     \"time\": 123456789,\n"
-                                                + "     \"value\": 100\n"
-                                                + "}";
-
-
-    private static final String jsonDataPoint2 = "{\n"
-                                                 + "     \"time\": 123456789,\n"
-                                                 + "     \"value\": 100.51\n"
-                                                 + "}";
-
-
-    private static final String jsonDataPoint3 = "{\n"
-                                                 + "     \"time\": 123456789,\n"
-                                                 + "     \"value\": \"110\"\n"
-                                                 + "}";
-
-    private static final String csvInts = "1,10,100,1000,";
-    private static final String otherReals = "1.0&2&5.0&10.";
-
-    @Test
-    public void testFromJson() throws Exception {
-        DataPoint dataPoint = DataPoint.fromJson(new JSONObject(jsonDataPoint));
-        assertEquals(123456789, dataPoint.getTime());
-        Object val = dataPoint.getValue();
-        assertTrue(val instanceof Long);
-        assertEquals(100, ((Long) val).longValue());
-
-        dataPoint = DataPoint.fromJson(new JSONObject(jsonDataPoint2));
-        assertEquals(123456789, dataPoint.getTime());
-        val = dataPoint.getValue();
-        assertTrue(val instanceof Double);
-        assertEquals(100.51, ((Double) val).doubleValue(), .05);
-
-        dataPoint = DataPoint.fromJson(new JSONObject(jsonDataPoint3));
-        assertEquals(123456789, dataPoint.getTime());
-        val = dataPoint.getValue();
-        assertTrue(val instanceof String);
-        assertEquals("110", val);
-
-    }
-
-    @Test
-    public void testToJson() throws Exception {
-        long now = System.currentTimeMillis();
-
-        DataPoint dataPointInt = new DataPoint(now, 10);
-        JSONObject json = dataPointInt.toJson();
-        assertEquals(now, json.getLong("time"));
-        assertEquals(10, json.getInt("value"));
-
-        DataPoint dataPointDouble = new DataPoint(now, 10.5);
-        json = dataPointDouble.toJson();
-        assertEquals(now, json.getLong("time"));
-        assertEquals(10.5, json.getDouble("value"), .1);
-
-        DataPoint dataPointString = new DataPoint(now, "11.2");
-        json = dataPointString.toJson();
-        assertEquals(now, json.getLong("time"));
-        assertEquals("11.2", json.getString("value"));
-    }
-
-    // REMOVE IN NEXT RELEASE
-
-    @Test
-    public void testCsvIntParse() throws Exception {
-        long ts = 1001;
-        List<DataPoint> list = DataPoint.parseDataPoints(csvInts, ",", Long.class, ts);
-        assertEquals(4, list.size());
-        for (DataPoint d : list) {
-            assertEquals(ts, d.getTime());
-        }
-        assertEquals(1l, list.get(0).getValue());
-        assertEquals(10l, list.get(1).getValue());
-        assertEquals(100l, list.get(2).getValue());
-        assertEquals(1000l, list.get(3).getValue());
-    }
-
-    @Test
-    public void testRealParse() throws Exception {
-        long ts = 2001;
-        List<DataPoint> list = DataPoint.parseDataPoints(otherReals, "&", Double.class, ts);
-        assertEquals(4, list.size());
-        for (DataPoint d : list) {
-            assertEquals(ts, d.getTime());
-        }
-        assertEquals(1d, list.get(0).getValue());
-        assertEquals(2d, list.get(1).getValue());
-        assertEquals(5d, list.get(2).getValue());
-        assertEquals(10d, list.get(3).getValue());
-    }
-
-    @Test
-    public void testInvalidTypeParse() throws Exception {
-        // Ideally, this call would be rejected as List is not an appropriate type, but we'll
-        // leave that as a TODO.
-        List<DataPoint> list = DataPoint.parseDataPoints(csvInts, ",", List.class);
-        assertEquals(0, list.size());
-    }
-}
+package com.iobeam.api.resource;
+
+import org.json.JSONObject;
+import org.junit.Test;
+
+import java.nio.ByteBuffer;
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+public class DataPointTest {
+
+    private static final String jsonDataPoint = "{\n"
+                                                + "     \"time\": 123456789,\n"
+                                                + "     \"value\": 100\n"
+                                                + "}";
+
+
+    private static final String jsonDataPoint2 = "{\n"
+                                                 + "     \"time\": 123456789,\n"
+                                                 + "     \"value\": 100.51\n"
+                                                 + "}";
+
+
+    private static final String jsonDataPoint3 = "{\n"
+                                                 + "     \"time\": 123456789,\n"
+                                                 + "     \"value\": \"110\"\n"
+                                                 + "}";
+
+    private static final String csvInts = "1,10,100,1000,";
+    private static final String otherReals = "1.0&2&5.0&10.";
+
+    @Test
+    public void testFromJson() throws Exception {
+        DataPoint dataPoint = DataPoint.fromJson(new JSONObject(jsonDataPoint));
+        assertEquals(123456789, dataPoint.getTime());
+        Object val = dataPoint.getValue();
+        assertTrue(val instanceof Long);
+        assertEquals(100, ((Long) val).longValue());
+
+        dataPoint = DataPoint.fromJson(new JSONObject(jsonDataPoint2));
+        assertEquals(123456789, dataPoint.getTime());
+        val = dataPoint.getValue();
+        assertTrue(val instanceof Double);
+        assertEquals(100.51, ((Double) val).doubleValue(), .05);
+
+        dataPoint = DataPoint.fromJson(new JSONObject(jsonDataPoint3));
+        assertEquals(123456789, dataPoint.getTime());
+        val = dataPoint.getValue();
+        assertTrue(val instanceof String);
+        assertEquals("110", val);
+
+    }
+
+    @Test
+    public void testToJson() throws Exception {
+        long now = System.currentTimeMillis();
+
+        DataPoint dataPointInt = new DataPoint(now, 10);
+        JSONObject json = dataPointInt.toJson();
+        assertEquals(now, json.getLong("time"));
+        assertEquals(10, json.getInt("value"));
+
+        DataPoint dataPointDouble = new DataPoint(now, 10.5);
+        json = dataPointDouble.toJson();
+        assertEquals(now, json.getLong("time"));
+        assertEquals(10.5, json.getDouble("value"), .1);
+
+        DataPoint dataPointString = new DataPoint(now, "11.2");
+        json = dataPointString.toJson();
+        assertEquals(now, json.getLong("time"));
+        assertEquals("11.2", json.getString("value"));
+    }
+
+    @Test
+    public void testToByteArray() throws Exception {
+        long now = System.currentTimeMillis();
+
+        DataPoint dataPointInt = new DataPoint(now, 10);
+        ByteBuffer buf = ByteBuffer.wrap(dataPointInt.toByteArray());
+        assertEquals(now, buf.getLong());
+        buf.get();  // skip type
+        assertEquals(10, buf.getLong());
+
+        DataPoint dataPointDouble = new DataPoint(now, 10.5);
+        buf = ByteBuffer.wrap(dataPointDouble.toByteArray());
+        assertEquals(now, buf.getLong());
+        buf.get();  // skip type
+        assertEquals(10.5, buf.getDouble(), .1);
+
+        DataPoint dataPointString = new DataPoint(now, "11.2");
+        buf = ByteBuffer.wrap(dataPointString.toByteArray());
+        assertEquals(now, buf.getLong());
+        buf.get();  // skip type
+        int strSize = buf.getInt();
+        byte[] temp = new byte[strSize];
+        buf.get(temp, 0, strSize);
+        assertEquals("11.2", new String(temp));
+    }
+
+    // REMOVE IN NEXT RELEASE
+
+    @Test
+    public void testCsvIntParse() throws Exception {
+        long ts = 1001;
+        List<DataPoint> list = DataPoint.parseDataPoints(csvInts, ",", Long.class, ts);
+        assertEquals(4, list.size());
+        for (DataPoint d : list) {
+            assertEquals(ts, d.getTime());
+        }
+        assertEquals(1l, list.get(0).getValue());
+        assertEquals(10l, list.get(1).getValue());
+        assertEquals(100l, list.get(2).getValue());
+        assertEquals(1000l, list.get(3).getValue());
+    }
+
+    @Test
+    public void testRealParse() throws Exception {
+        long ts = 2001;
+        List<DataPoint> list = DataPoint.parseDataPoints(otherReals, "&", Double.class, ts);
+        assertEquals(4, list.size());
+        for (DataPoint d : list) {
+            assertEquals(ts, d.getTime());
+        }
+        assertEquals(1d, list.get(0).getValue());
+        assertEquals(2d, list.get(1).getValue());
+        assertEquals(5d, list.get(2).getValue());
+        assertEquals(10d, list.get(3).getValue());
+    }
+
+    @Test
+    public void testInvalidTypeParse() throws Exception {
+        // Ideally, this call would be rejected as List is not an appropriate type, but we'll
+        // leave that as a TODO.
+        List<DataPoint> list = DataPoint.parseDataPoints(csvInts, ",", List.class);
+        assertEquals(0, list.size());
+    }
+}