generalizing inmemory map into any sensor

modules/samples/virtual_firealarm/src/org.wso2.carbon.device.mgt.iot.sample.virtual.firealarm.service.impl/src/main/java/org/wso2/carbon/device/mgt/iot/sample/virtual/firealarm/service/impl/dao/DeviceRecord.java

@@ -20,11 +20,11 @@ import javax.xml.bind.annotation.XmlElement;
 import javax.xml.bind.annotation.XmlRootElement;
 
 @XmlRootElement
-public class TemperatureRecord {
+public class DeviceRecord {
     private double temperature;
     private long time;
 
-    public TemperatureRecord(double temperature, long time) {
+    public DeviceRecord(double temperature, long time) {
         this.temperature = temperature;
         this.time = time;
     }

modules/samples/virtual_firealarm/src/org.wso2.carbon.device.mgt.iot.sample.virtual.firealarm.service.impl/src/main/java/org/wso2/carbon/device/mgt/iot/sample/virtual/firealarm/service/impl/dao/SensorRecord.java

@@ -0,0 +1,24 @@
+package org.wso2.carbon.device.mgt.iot.sample.virtual.firealarm.service.impl.dao;
+
+import javax.xml.bind.annotation.XmlElement;
+
+public class SensorRecord {
+	private String sensorValue;
+	private long time;
+
+	public SensorRecord(String sensorValue, long time) {
+		this.sensorValue = sensorValue;
+		this.time = time;
+	}
+
+	@XmlElement
+	public String getSensorValue() {
+		return sensorValue;
+	}
+
+	@XmlElement
+	public long getTime() {
+		return time;
+	}
+
+}