Fixed EMM-1531

components/device-mgt/org.wso2.carbon.device.mgt.api/src/main/java/org/wso2/carbon/device/mgt/jaxrs/service/impl/DeviceManagementServiceImpl.java

@@ -189,9 +189,25 @@ public class DeviceManagementServiceImpl implements DeviceManagementService {
         Device device;
         try {
             RequestValidationUtil.validateDeviceIdentifier(type, id);
-
             DeviceManagementProviderService dms = DeviceMgtAPIUtils.getDeviceManagementService();
-            device = dms.getDevice(new DeviceIdentifier(id, type));
+            if (ifModifiedSince != null && !ifModifiedSince.isEmpty()) {
+                Date sinceDate;
+                SimpleDateFormat format = new SimpleDateFormat("EEE, d MMM yyyy HH:mm:ss Z");
+                try {
+                    sinceDate = format.parse(ifModifiedSince);
+                } catch (ParseException e) {
+                    return Response.status(Response.Status.BAD_REQUEST).entity(
+                            new ErrorResponse.ErrorResponseBuilder().setMessage("Invalid date " +
+                                                                                "string is provided in 'If-Modified-Since' header").build()).build();
+                }
+                device = dms.getDevice(new DeviceIdentifier(id, type), sinceDate);
+                if (device == null) {
+                    return Response.status(Response.Status.NOT_MODIFIED).entity("No device is modified " +
+                                                                                "after the timestamp provided in 'If-Modified-Since' header").build();
+                }
+            } else {
+                device = dms.getDevice(new DeviceIdentifier(id, type));
+            }
         } catch (DeviceManagementException e) {
             String msg = "Error occurred while fetching the device information.";
             log.error(msg, e);

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/dao/DeviceDAO.java

@@ -25,6 +25,7 @@ import org.wso2.carbon.device.mgt.common.EnrolmentInfo.Status;
 import org.wso2.carbon.device.mgt.common.PaginationRequest;
 import org.wso2.carbon.device.mgt.core.dto.DeviceType;
 
+import java.util.Date;
 import java.util.HashMap;
 import java.util.List;
 
@@ -124,6 +125,18 @@ public interface DeviceDAO {
      */
     Device getDevice(DeviceIdentifier deviceIdentifier, int tenantId) throws DeviceManagementDAOException;
 
+    /**
+     * This method is used to retrieve a device of a given device-identifier and tenant-id.
+     *
+     * @param deviceIdentifier device id.
+     * @param ifModifiedSince last modified time.
+     * @param tenantId tenant id.
+     * @return returns the device object.
+     * @throws DeviceManagementDAOException
+     */
+    Device getDevice(DeviceIdentifier deviceIdentifier, Date ifModifiedSince, int tenantId) throws
+                                                                                            DeviceManagementDAOException;
+
     /**
      * This method is used to retrieve a device of a given device-identifier, enrollment status and tenant-id.
      *

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/dao/impl/AbstractDeviceDAOImpl.java

@@ -128,7 +128,7 @@ public abstract class AbstractDeviceDAOImpl implements DeviceDAO {
             stmt.setInt(4, tenantId);
             rs = stmt.executeQuery();
             if (rs.next()) {
-                device = DeviceManagementDAOUtil.loadMatchingDevice(rs);
+                device = DeviceManagementDAOUtil.loadMatchingDevice(rs, false);
             }
         } catch (SQLException e) {
             throw new DeviceManagementDAOException("Error occurred while listing devices for type " +
@@ -139,6 +139,41 @@ public abstract class AbstractDeviceDAOImpl implements DeviceDAO {
         return device;
     }
 
+    @Override
+    public Device getDevice(DeviceIdentifier deviceIdentifier, Date since, int tenantId)
+                                                                                 throws DeviceManagementDAOException {
+        Connection conn;
+        PreparedStatement stmt = null;
+        ResultSet rs = null;
+        Device device = null;
+        try {
+            conn = this.getConnection();
+            String sql = "SELECT d1.ID AS DEVICE_ID, d1.DESCRIPTION, d1.NAME AS DEVICE_NAME, d1.DEVICE_TYPE, " +
+                         "d1.DEVICE_IDENTIFICATION, e.OWNER, e.OWNERSHIP, e.STATUS, e.DATE_OF_LAST_UPDATE, " +
+                         "e.DATE_OF_ENROLMENT, e.ID AS ENROLMENT_ID FROM DM_ENROLMENT e, (SELECT d.ID, d.DESCRIPTION, d.NAME, " +
+                         "t.NAME AS DEVICE_TYPE, d.DEVICE_IDENTIFICATION FROM DM_DEVICE d, DM_DEVICE_TYPE t, DM_DEVICE_DETAIL dt " +
+                         "WHERE t.NAME = ? AND d.DEVICE_IDENTIFICATION = ? AND d.TENANT_ID = ? AND dt.DEVICE_ID = d.ID " +
+                         "AND dt.UPDATE_TIMESTAMP > ?) d1 WHERE d1.ID = e.DEVICE_ID AND TENANT_ID = ?" ;
+            stmt = conn.prepareStatement(sql);
+            int paramIdx = 1;
+            stmt.setString(paramIdx++, deviceIdentifier.getType());
+            stmt.setString(paramIdx++, deviceIdentifier.getId());
+            stmt.setInt(paramIdx++, tenantId);
+            stmt.setLong(paramIdx++, since.getTime());
+            stmt.setInt(paramIdx, tenantId);
+            rs = stmt.executeQuery();
+            if (rs.next()) {
+                device = DeviceManagementDAOUtil.loadMatchingDevice(rs, true);
+            }
+        } catch (SQLException e) {
+            throw new DeviceManagementDAOException("Error occurred while listing device for type " +
+                                                   "'" + deviceIdentifier.getType() + "'", e);
+        } finally {
+            DeviceManagementDAOUtil.cleanupResources(stmt, rs);
+        }
+        return device;
+    }
+
     @Override
     public Device getDevice(DeviceIdentifier deviceIdentifier, EnrolmentInfo.Status status, int tenantId) throws
                                                                                          DeviceManagementDAOException {

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/dao/util/DeviceManagementDAOUtil.java

@@ -160,14 +160,21 @@ public final class DeviceManagementDAOUtil {
 
     //This method will retrieve most appropriate device information when there are multiple device enrollments for
     //a single device. We'll give the highest priority to active devices.
-    public static Device loadMatchingDevice(ResultSet rs) throws SQLException {
+    public static Device loadMatchingDevice(ResultSet rs, boolean deviceInfoIncluded) throws SQLException {
         Map<EnrolmentInfo.Status, Device> deviceMap = new HashMap<>();
         Device device = loadDevice(rs);
+        if (deviceInfoIncluded) {
+            device.setDeviceInfo(loadDeviceInfo(rs));
+        }
+
         if (EnrolmentInfo.Status.ACTIVE.equals(device.getEnrolmentInfo().getStatus())) {
             return device;
         }
         while (rs.next()) {
             device = loadDevice(rs);
+            if (deviceInfoIncluded) {
+                device.setDeviceInfo(loadDeviceInfo(rs));
+            }
             if (EnrolmentInfo.Status.ACTIVE.equals(device.getEnrolmentInfo().getStatus())) {
                 return device;
             }

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/service/DeviceManagementProviderService.java

@@ -25,6 +25,7 @@ import org.wso2.carbon.device.mgt.common.operation.mgt.Operation;
 import org.wso2.carbon.device.mgt.common.operation.mgt.OperationManagementException;
 import org.wso2.carbon.device.mgt.core.dto.DeviceType;
 
+import java.util.Date;
 import java.util.List;
 
 /**
@@ -205,6 +206,8 @@ public interface DeviceManagementProviderService {
 
     Device getDevice(DeviceIdentifier deviceId) throws DeviceManagementException;
 
+    Device getDevice(DeviceIdentifier deviceId, Date since) throws DeviceManagementException;
+
     Device getDevice(DeviceIdentifier deviceId, EnrolmentInfo.Status status) throws DeviceManagementException;
 
     List<String> getAvailableDeviceTypes() throws DeviceManagementException;

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/service/DeviceManagementProviderServiceImpl.java

@@ -807,6 +807,54 @@ public class DeviceManagementProviderServiceImpl implements DeviceManagementProv
         return device;
     }
 
+    @Override
+    public Device getDevice(DeviceIdentifier deviceId, Date since) throws DeviceManagementException {
+        Device device;
+        try {
+            DeviceManagementDAOFactory.openConnection();
+            device = deviceDAO.getDevice(deviceId, since, this.getTenantId());
+            if (device == null) {
+                if (log.isDebugEnabled()) {
+                    log.debug("No device is found upon the type '" + deviceId.getType() + "' and id '" +
+                              deviceId.getId() + "'");
+                }
+                return null;
+            }
+            DeviceLocation location = deviceInfoDAO.getDeviceLocation(device.getId());
+            if (device.getDeviceInfo() != null) {
+                device.getDeviceInfo().setLocation(location);
+            }
+
+            List<Application> applications = applicationDAO.getInstalledApplications(device.getId());
+            device.setApplications(applications);
+        } catch (DeviceManagementDAOException e) {
+            throw new DeviceManagementException("Error occurred while obtaining the device for id " +
+                                                "'" + deviceId.getId() + "'", e);
+        } catch (SQLException e) {
+            throw new DeviceManagementException("Error occurred while opening a connection to the data source", e);
+        } catch (DeviceDetailsMgtDAOException e) {
+            throw new DeviceManagementException("Error occurred while fetching advanced device information", e);
+        } finally {
+            DeviceManagementDAOFactory.closeConnection();
+        }
+        // The changes made here to prevent unit tests getting failed. They failed because when running the unit
+        // tests there is no osgi services. So getDeviceManager() returns a null.
+        DeviceManager deviceManager = this.getDeviceManager(deviceId.getType());
+        if (deviceManager == null) {
+            if (log.isDebugEnabled()) {
+                log.debug("Device Manager associated with the device type '" + deviceId.getType() + "' is null. " +
+                          "Therefore, not attempting method 'getDevice'");
+            }
+            return device;
+        }
+        Device pluginSpecificInfo = deviceManager.getDevice(deviceId);
+        if (pluginSpecificInfo != null) {
+            device.setFeatures(pluginSpecificInfo.getFeatures());
+            device.setProperties(pluginSpecificInfo.getProperties());
+        }
+        return device;
+    }
+
     @Override
     public Device getDevice(DeviceIdentifier deviceId, EnrolmentInfo.Status status) throws DeviceManagementException {
         Device device;