Add support to generic resources and refactor in classes to support types and commandpattern.

15 files changed, 521 insertions, 109 deletions

diff --git a/src/org/traccar/database/DataManager.java b/src/org/traccar/database/DataManager.java
index 24a07a05c..767582604 100644
--- a/src/org/traccar/database/DataManager.java
+++ b/src/org/traccar/database/DataManager.java
@@ -379,4 +379,43 @@ public class DataManager implements IdentityManager {
                 .executeUpdate();
     }
 
+    public void add(Object entity) throws SQLException {
+        if (entity instanceof User) {
+            addUser((User) entity);
+        } else if (entity instanceof Device) {
+            addDevice((Device) entity);
+        } else if (entity instanceof Position) {
+            addPosition((Position) entity);
+        }
+    }
+
+    public void update(Object entity) throws SQLException {
+        if (entity instanceof User) {
+            updateUser((User) entity);
+        } else if (entity instanceof Device) {
+            updateDevice((Device) entity);
+        } else if (entity instanceof Server) {
+            updateServer((Server) entity);
+        }
+    }
+
+    public void remove(Object entity) throws SQLException {
+        if (entity instanceof User) {
+            removeUser((User) entity);
+        } else if (entity instanceof Device) {
+            removeDevice((Device) entity);
+        }
+    }
+
+    public void link(Class clazz, long userId, long entityId) throws SQLException {
+        if (clazz.equals(Device.class)) {
+            linkDevice(userId, entityId);
+        }
+    }
+
+    public void unlink(Class clazz, long userId, long entityId) throws SQLException {
+        if (clazz.equals(Device.class)) {
+            unlinkDevice(userId, entityId);
+        }
+    }
 }
diff --git a/src/org/traccar/database/PermissionsManager.java b/src/org/traccar/database/PermissionsManager.java
index a38a29c32..138641973 100644
--- a/src/org/traccar/database/PermissionsManager.java
+++ b/src/org/traccar/database/PermissionsManager.java
@@ -22,6 +22,7 @@ import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 import org.traccar.helper.Log;
+import org.traccar.model.Device;
 import org.traccar.model.Permission;
 import org.traccar.model.User;
 
@@ -66,7 +67,7 @@ public class PermissionsManager {
         }
     }
 
-    public void checkUser(long userId, long otherUserId) throws SecurityException {
+    private void checkUser(long userId, long otherUserId) throws SecurityException {
         if (userId != otherUserId) {
             checkAdmin(userId);
         }
@@ -76,10 +77,17 @@ public class PermissionsManager {
         return getNotNull(userId);
     }
 
-    public void checkDevice(long userId, long deviceId) throws SecurityException {
+    private void checkDevice(long userId, long deviceId) throws SecurityException {
         if (!getNotNull(userId).contains(deviceId)) {
             throw new SecurityException("Device access denied");
         }
     }
 
+    public <T> void check(Class<T> clazz, long userId, long entityId) throws SecurityException {
+        if (clazz.equals(User.class)) {
+            checkUser(userId, entityId);
+        } else if (clazz.equals(Device.class)) {
+            checkDevice(userId, entityId);
+        }
+    }
 }
diff --git a/src/org/traccar/helper/Clazz.java b/src/org/traccar/helper/Clazz.java
new file mode 100644
index 000000000..bdde940a0
--- /dev/null
+++ b/src/org/traccar/helper/Clazz.java
@@ -0,0 +1,105 @@
+/*
+ * Copyright 2015 Anton Tananaev (anton.tananaev@gmail.com)
+ *
+ * Licensed 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.traccar.helper;
+
+import java.beans.Introspector;
+import java.lang.reflect.Method;
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+
+public final class Clazz {
+
+    private Clazz() {
+    }
+
+    public static Class getGenericArgumentType(Class currentClass, Class genericSuperClass) {
+        return getGenericArgumentType(currentClass, genericSuperClass, 0);
+    }
+
+    public static Class getGenericArgumentType(Class currentClass, int argumentIndex) {
+        return getGenericArgumentType(currentClass, null, argumentIndex);
+    }
+
+    public static Class getGenericArgumentType(Class currentClass) {
+        return getGenericArgumentType(currentClass, null, 0);
+    }
+
+    public static Class getGenericArgumentType(Class currentClass, Class genericSuperClass, int argumentIndex) {
+        Type superType = currentClass.getGenericSuperclass();
+        if (superType == null) {
+            throw new IllegalArgumentException();
+        }
+        if (!(superType instanceof ParameterizedType)
+                || genericSuperClass != null
+                && ((ParameterizedType) superType).getRawType() != genericSuperClass) {
+            return getGenericArgumentType(currentClass.getSuperclass(), genericSuperClass, argumentIndex);
+        }
+        Object[] args = ((ParameterizedType) superType).getActualTypeArguments();
+        if (argumentIndex >= args.length) {
+            throw new IllegalArgumentException();
+        }
+        return cast(Class.class, args[argumentIndex]);
+    }
+
+    public static <T> T newInstance(Class<T> clazz) {
+        try {
+            return clazz.newInstance();
+        } catch (InstantiationException | IllegalAccessException e) {
+            throw new IllegalArgumentException();
+        }
+    }
+
+    public static <T> T cast(Class<T> classe, Object objeto) {
+        if (classe.isAssignableFrom(objeto.getClass())) {
+            return classe.cast(objeto);
+        }
+        throw new ClassCastException();
+    }
+
+    public static Class forName(String className) {
+        try {
+            return Class.forName(className, false, Thread.currentThread().getContextClassLoader());
+        } catch (ClassNotFoundException e) {
+            throw new IllegalArgumentException(e);
+        }
+    }
+
+    public static long getId(Object entity) throws Exception {
+        Method[] methods = entity.getClass().getMethods();
+        for (final Method method : methods) {
+            if (method.getName().startsWith("get") && method.getParameterTypes().length == 0) {
+                final String name = Introspector.decapitalize(method.getName().substring(3));
+                if (name.equals("id")) {
+                    return Long.parseLong(method.invoke(entity).toString());
+                }
+            }
+        }
+        throw new IllegalArgumentException();
+    }
+
+    public static void setId(Object entity, long id) throws Exception {
+        Method[] methods = entity.getClass().getMethods();
+        for (final Method method : methods) {
+            if (method.getName().startsWith("set") && method.getParameterTypes().length == 1) {
+                final String name = Introspector.decapitalize(method.getName().substring(3));
+                if (name.equals("id")) {
+                    method.invoke(entity, id);
+                    break;
+                }
+            }
+        }
+    }
+}
diff --git a/src/org/traccar/helper/CommandCall.java b/src/org/traccar/helper/CommandCall.java
new file mode 100644
index 000000000..d5da79348
--- /dev/null
+++ b/src/org/traccar/helper/CommandCall.java
@@ -0,0 +1,51 @@
+/*
+ * Copyright 2015 Anton Tananaev (anton.tananaev@gmail.com)
+ *
+ * Licensed 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.traccar.helper;
+
+public abstract class CommandCall<T> {
+
+    private long userId;
+    private T entity;
+
+    public void before() throws Exception {
+        //Do nothing.
+    }
+
+    public void check() throws Exception {
+        //Do nothing.
+    }
+
+    public void after() throws Exception {
+        //Do nothing.
+    }
+
+    public long getUserId() {
+        return userId;
+    }
+
+    public void setUserId(long userId) {
+        this.userId = userId;
+    }
+
+    public T getEntity() {
+        return entity;
+    }
+
+    public void setEntity(T entity) {
+        this.entity = entity;
+    }
+
+}
diff --git a/src/org/traccar/web/BaseServlet.java b/src/org/traccar/web/BaseServlet.java
index 283edf1e5..916eb6a18 100644
--- a/src/org/traccar/web/BaseServlet.java
+++ b/src/org/traccar/web/BaseServlet.java
@@ -37,15 +37,11 @@ import org.traccar.model.User;
 
 public abstract class BaseServlet extends HttpServlet {
 
-    public static final String USER_KEY = "user";
+    public static final String USER_ID_KEY = "user";
     public static final String ALLOW_ORIGIN_VALUE = "*";
     public static final String ALLOW_HEADERS_VALUE = "Origin, X-Requested-With, Content-Type, Accept";
     public static final String ALLOW_METHODS_VALUE = "GET, POST, PUT, DELETE";
     public static final String APPLICATION_JSON = "application/json";
-    public static final String GET = "GET";
-    public static final String POST = "POST";
-    public static final String PUT = "PUT";
-    public static final String DELETE = "DELETE";
 
     @Override
     protected final void service(
@@ -82,6 +78,10 @@ public abstract class BaseServlet extends HttpServlet {
             String command, HttpServletRequest req, HttpServletResponse resp) throws Exception;
 
     public long getUserId(HttpServletRequest req) throws Exception  {
+        Object userId = req.getSession().getAttribute(USER_ID_KEY);
+        if (userId != null) {
+            return (Long) userId;
+        }
         String authorization = req.getHeader(HttpHeaders.Names.AUTHORIZATION);
         if (authorization != null && !authorization.isEmpty()) {
             Map<String, String> authMap = Authorization.parse(authorization);
@@ -92,11 +92,7 @@ public abstract class BaseServlet extends HttpServlet {
                 return user.getId();
             }
         }
-        Long userId = (Long) req.getSession().getAttribute(USER_KEY);
-        if (userId == null) {
-            throw new AccessControlException("User not logged in");
-        }
-        return userId;
+        throw new AccessControlException("User not logged in");
     }
 
     public void sendResponse(Writer writer, boolean success) throws IOException {
@@ -129,26 +125,12 @@ public abstract class BaseServlet extends HttpServlet {
         writer.write(result.build().toString());
     }
 
-    private String getCommand(HttpServletRequest req) {
+    protected String getCommand(HttpServletRequest req) {
         String command = req.getPathInfo();
         if (command == null) {
-            switch (req.getMethod()) {
-                case GET:
-                    command = "/get";
-                    break;
-                case POST:
-                    command = "/add";
-                    break;
-                case PUT:
-                    command = "/update";
-                    break;
-                case DELETE:
-                    command = "/remove";
-                    break;
-                default:
-                    command = "";
-            }
+            command = "";
         }
         return command;
     }
+
 }
diff --git a/src/org/traccar/web/BaseServletResource.java b/src/org/traccar/web/BaseServletResource.java
new file mode 100644
index 000000000..318f0d7b6
--- /dev/null
+++ b/src/org/traccar/web/BaseServletResource.java
@@ -0,0 +1,169 @@
+/*
+ * Copyright 2015 Anton Tananaev (anton.tananaev@gmail.com)
+ *
+ * Licensed 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.traccar.web;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import org.traccar.Context;
+import org.traccar.helper.CommandCall;
+import org.traccar.helper.Clazz;
+
+/**
+ *
+ * @author Rafael
+ */
+public abstract class BaseServletResource<T> extends BaseServlet {
+
+    private final Class<T> clazz = Clazz.getGenericArgumentType(getClass());
+
+    public static final String GET = "GET";
+    public static final String POST = "POST";
+    public static final String PUT = "PUT";
+    public static final String DELETE = "DELETE";
+
+    public static final String PATH_PARAM_ID = "/\\d";
+    public static final String SLASH = "/";
+    public static final String VOID = "";
+
+    @Override
+    protected String getCommand(HttpServletRequest req) {
+        String command = req.getPathInfo();
+        if (command == null || command.matches(PATH_PARAM_ID)) {
+            switch (req.getMethod()) {
+                case GET:
+                    command = "/get";
+                    break;
+                case POST:
+                    command = "/add";
+                    break;
+                case PUT:
+                    command = "/update";
+                    break;
+                case DELETE:
+                    command = "/remove";
+                    break;
+                default:
+                    command = "";
+            }
+        }
+        return command;
+    }
+
+    protected String getPathParamId(String pathInfo) {
+        if (pathInfo != null && pathInfo.matches(PATH_PARAM_ID)) {
+            return pathInfo.replaceAll(SLASH, VOID);
+        }
+        return null;
+    }
+
+    protected abstract void get(HttpServletRequest req, HttpServletResponse resp) throws Exception;
+
+    protected void add(HttpServletRequest req, HttpServletResponse resp) throws Exception {
+        add(req, resp, null);
+    }
+
+    protected void update(HttpServletRequest req, HttpServletResponse resp) throws Exception {
+        update(req, resp, null);
+    }
+
+    protected void remove(HttpServletRequest req, HttpServletResponse resp) throws Exception {
+        remove(req, resp, null);
+    }
+
+    protected void add(HttpServletRequest req, HttpServletResponse resp, CommandCall<T> commandCall) throws Exception {
+        if (commandCall != null) {
+            commandCall.before();
+        }
+
+        T entity = JsonConverter.objectFromJson(req.getReader(), this.clazz);
+        long userId = getUserId(req);
+        if (commandCall != null) {
+            commandCall.setUserId(userId);
+            commandCall.setEntity(entity);
+            commandCall.check();
+        }
+
+        Context.getDataManager().add(entity);
+
+        long entityId = Clazz.getId(entity);
+        Context.getDataManager().link(this.clazz, userId, entityId);
+
+        if (commandCall != null) {
+            commandCall.after();
+        }
+
+        sendResponse(resp.getWriter(), JsonConverter.objectToJson(entity));
+    }
+
+    protected void update(HttpServletRequest req, HttpServletResponse resp,
+                          CommandCall<T> commandCall) throws Exception {
+        if (commandCall != null) {
+            commandCall.before();
+        }
+
+        T entity = JsonConverter.objectFromJson(req.getReader(), this.clazz);
+        String entityId = getPathParamId(req.getPathInfo());
+        if (entityId != null) {
+            Clazz.setId(entity, Long.parseLong(entityId));
+        }
+        long userId = getUserId(req);
+
+        if (commandCall != null) {
+            commandCall.setUserId(userId);
+            commandCall.setEntity(entity);
+            commandCall.check();
+        }
+
+        Context.getDataManager().update(entity);
+
+        if (commandCall != null) {
+            commandCall.after();
+        }
+
+        sendResponse(resp.getWriter(), true);
+    }
+
+    protected void remove(HttpServletRequest req, HttpServletResponse resp,
+                          CommandCall<T> commandCall) throws Exception {
+        if (commandCall != null) {
+            commandCall.before();
+        }
+
+        T entity = Clazz.newInstance(this.clazz);
+        String entityId = getPathParamId(req.getPathInfo());
+        if (entityId != null) {
+            Clazz.setId(entity, Long.parseLong(entityId));
+        } else {
+            entity = JsonConverter.objectFromJson(req.getReader(), this.clazz);
+        }
+        long userId = getUserId(req);
+
+        if (commandCall != null) {
+            commandCall.setUserId(userId);
+            commandCall.setEntity(entity);
+            commandCall.check();
+        }
+
+        Context.getDataManager().remove(entity);
+
+        if (commandCall != null) {
+            commandCall.after();
+        }
+
+        sendResponse(resp.getWriter(), true);
+    }
+
+}
diff --git a/src/org/traccar/web/CommandServlet.java b/src/org/traccar/web/CommandServlet.java
index 958f1a888..be2d50ccc 100644
--- a/src/org/traccar/web/CommandServlet.java
+++ b/src/org/traccar/web/CommandServlet.java
@@ -7,6 +7,7 @@ import javax.servlet.http.HttpServletResponse;
 import org.traccar.Context;
 import org.traccar.database.ActiveDevice;
 import org.traccar.model.Command;
+import org.traccar.model.Device;
 
 public class CommandServlet extends BaseServlet {
 
@@ -34,19 +35,17 @@ public class CommandServlet extends BaseServlet {
     }
 
     private void send(HttpServletRequest req, HttpServletResponse resp) throws Exception {
-
-        Command command = JsonConverter.objectFromJson(req.getReader(), new Command());
-        Context.getPermissionsManager().checkDevice(getUserId(req), command.getDeviceId());
+        Command command = JsonConverter.objectFromJson(req.getReader(), Command.class);
+        Context.getPermissionsManager().check(Device.class, getUserId(req), command.getDeviceId());
         getActiveDevice(command.getDeviceId()).sendCommand(command);
         sendResponse(resp.getWriter(), true);
     }
 
     private void raw(HttpServletRequest req, HttpServletResponse resp) throws Exception {
-
         JsonObject json = Json.createReader(req.getReader()).readObject();
         long deviceId = json.getJsonNumber("deviceId").longValue();
         String command = json.getString("command");
-        Context.getPermissionsManager().checkDevice(getUserId(req), deviceId);
+        Context.getPermissionsManager().check(Device.class, getUserId(req), deviceId);
         getActiveDevice(deviceId).write(command);
         sendResponse(resp.getWriter(), true);
     }
diff --git a/src/org/traccar/web/DeviceServlet.java b/src/org/traccar/web/DeviceServlet.java
index 8f983ad78..7900538bb 100644
--- a/src/org/traccar/web/DeviceServlet.java
+++ b/src/org/traccar/web/DeviceServlet.java
@@ -18,9 +18,11 @@ package org.traccar.web;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import org.traccar.Context;
+import org.traccar.helper.CommandCall;
 import org.traccar.model.Device;
+import org.traccar.model.User;
 
-public class DeviceServlet extends BaseServlet {
+public class DeviceServlet extends BaseServletResource<Device> {
 
     @Override
     protected boolean handle(String command, HttpServletRequest req, HttpServletResponse resp) throws Exception {
@@ -50,7 +52,8 @@ public class DeviceServlet extends BaseServlet {
         return true;
     }
 
-    private void get(HttpServletRequest req, HttpServletResponse resp) throws Exception {
+    @Override
+    protected void get(HttpServletRequest req, HttpServletResponse resp) throws Exception {
         if (Boolean.parseBoolean(req.getParameter("all"))) {
             Context.getPermissionsManager().checkAdmin(getUserId(req));
             sendResponse(resp.getWriter(), JsonConverter.arrayToJson(
@@ -63,39 +66,57 @@ public class DeviceServlet extends BaseServlet {
             } else {
                 userId = getUserId(req);
             }
-            Context.getPermissionsManager().checkUser(getUserId(req), userId);
+            Context.getPermissionsManager().check(User.class, getUserId(req), userId);
             sendResponse(resp.getWriter(), JsonConverter.arrayToJson(
                     Context.getDataManager().getDevices(userId)));
         }
     }
 
-    private void add(HttpServletRequest req, HttpServletResponse resp) throws Exception {
-        Device device = JsonConverter.objectFromJson(req.getReader(), new Device());
-        long userId = getUserId(req);
-        Context.getDataManager().addDevice(device);
-        Context.getDataManager().linkDevice(userId, device.getId());
-        Context.getPermissionsManager().refresh();
-        sendResponse(resp.getWriter(), JsonConverter.objectToJson(device));
+    @Override
+    protected void add(HttpServletRequest req, HttpServletResponse resp) throws Exception {
+        super.add(req, resp, new CommandCall<Device>() {
+
+            @Override
+            public void after() throws Exception {
+                Context.getDataManager().link(Device.class, getUserId(), getEntity().getId());
+                Context.getPermissionsManager().refresh();
+            }
+
+        });
     }
 
-    private void update(HttpServletRequest req, HttpServletResponse resp) throws Exception {
-        Device device = JsonConverter.objectFromJson(req.getReader(), new Device());
-        Context.getPermissionsManager().checkDevice(getUserId(req), device.getId());
-        Context.getDataManager().updateDevice(device);
-        sendResponse(resp.getWriter(), true);
+    @Override
+    protected void update(HttpServletRequest req, HttpServletResponse resp) throws Exception {
+        super.update(req, resp, new CommandCall<Device>() {
+
+            @Override
+            public void check() throws Exception {
+                Context.getPermissionsManager().check(Device.class, getUserId(), getEntity().getId());
+            }
+
+        });
     }
 
-    private void remove(HttpServletRequest req, HttpServletResponse resp) throws Exception {
-        Device device = JsonConverter.objectFromJson(req.getReader(), new Device());
-        Context.getPermissionsManager().checkDevice(getUserId(req), device.getId());
-        Context.getDataManager().removeDevice(device);
-        Context.getPermissionsManager().refresh();
-        sendResponse(resp.getWriter(), true);
+    @Override
+    protected void remove(HttpServletRequest req, HttpServletResponse resp) throws Exception {
+        super.remove(req, resp, new CommandCall<Device>() {
+
+            @Override
+            public void check() throws Exception {
+                Context.getPermissionsManager().check(Device.class, getUserId(), getEntity().getId());
+            }
+
+            @Override
+            public void after() throws Exception {
+                Context.getPermissionsManager().refresh();
+            }
+
+        });
     }
 
     private void link(HttpServletRequest req, HttpServletResponse resp) throws Exception {
         Context.getPermissionsManager().checkAdmin(getUserId(req));
-        Context.getDataManager().linkDevice(
+        Context.getDataManager().link(Device.class,
                 Long.parseLong(req.getParameter("userId")),
                 Long.parseLong(req.getParameter("deviceId")));
         Context.getPermissionsManager().refresh();
@@ -104,7 +125,7 @@ public class DeviceServlet extends BaseServlet {
 
     private void unlink(HttpServletRequest req, HttpServletResponse resp) throws Exception {
         Context.getPermissionsManager().checkAdmin(getUserId(req));
-        Context.getDataManager().unlinkDevice(
+        Context.getDataManager().unlink(Device.class,
                 Long.parseLong(req.getParameter("userId")),
                 Long.parseLong(req.getParameter("deviceId")));
         Context.getPermissionsManager().refresh();
diff --git a/src/org/traccar/web/JsonConverter.java b/src/org/traccar/web/JsonConverter.java
index b19894dd6..d39e6b488 100644
--- a/src/org/traccar/web/JsonConverter.java
+++ b/src/org/traccar/web/JsonConverter.java
@@ -34,8 +34,8 @@ import javax.json.JsonValue;
 import org.joda.time.DateTime;
 import org.joda.time.format.DateTimeFormatter;
 import org.joda.time.format.ISODateTimeFormat;
+import org.traccar.helper.Clazz;
 import org.traccar.helper.Log;
-import org.traccar.model.Factory;
 import org.traccar.model.MiscFormatter;
 
 public final class JsonConverter {
@@ -49,17 +49,15 @@ public final class JsonConverter {
         return DATE_FORMAT.parseDateTime(value).toDate();
     }
 
-    public static <T extends Factory> T objectFromJson(Reader reader, T prototype) throws ParseException {
+    public static <T> T objectFromJson(Reader reader, Class<T> clazz) throws ParseException {
         try (JsonReader jsonReader = Json.createReader(reader)) {
-            return objectFromJson(jsonReader.readObject(), prototype);
+            return objectFromJson(jsonReader.readObject(), clazz);
         }
     }
 
-    public static <T extends Factory> T objectFromJson(JsonObject json, T prototype) {
-        T object = (T) prototype.create();
-
+    public static <T> T objectFromJson(JsonObject json, Class<T> clazz) {
+        T object = Clazz.newInstance(clazz);
         Method[] methods = object.getClass().getMethods();
-
         for (final Method method : methods) {
             if (method.getName().startsWith("set") && method.getParameterTypes().length == 1) {
 
@@ -91,7 +89,6 @@ public final class JsonConverter {
                 }
             }
         }
-
         return object;
     }
 
diff --git a/src/org/traccar/web/MainServlet.java b/src/org/traccar/web/MainServlet.java
index 63ff27813..40bfcddb5 100644
--- a/src/org/traccar/web/MainServlet.java
+++ b/src/org/traccar/web/MainServlet.java
@@ -45,7 +45,7 @@ public class MainServlet extends BaseServlet {
     }
 
     private void session(HttpServletRequest req, HttpServletResponse resp) throws Exception {
-        Long userId = (Long) req.getSession().getAttribute(USER_KEY);
+        Long userId = (Long) req.getSession().getAttribute(USER_ID_KEY);
         if (userId != null) {
             sendResponse(resp.getWriter(), JsonConverter.objectToJson(
                     Context.getDataManager().getUser(userId)));
@@ -58,7 +58,7 @@ public class MainServlet extends BaseServlet {
         User user = Context.getDataManager().login(
                 req.getParameter("email"), req.getParameter("password"));
         if (user != null) {
-            req.getSession().setAttribute(USER_KEY, user.getId());
+            req.getSession().setAttribute(USER_ID_KEY, user.getId());
             sendResponse(resp.getWriter(), JsonConverter.objectToJson(user));
         } else {
             sendResponse(resp.getWriter(), false);
@@ -66,12 +66,12 @@ public class MainServlet extends BaseServlet {
     }
 
     private void logout(HttpServletRequest req, HttpServletResponse resp) throws Exception {
-        req.getSession().removeAttribute(USER_KEY);
+        req.getSession().removeAttribute(USER_ID_KEY);
         sendResponse(resp.getWriter(), true);
     }
 
     private void register(HttpServletRequest req, HttpServletResponse resp) throws Exception {
-        User user = JsonConverter.objectFromJson(req.getReader(), new User());
+        User user = JsonConverter.objectFromJson(req.getReader(), User.class);
         Context.getDataManager().addUser(user);
         sendResponse(resp.getWriter(), true);
     }
diff --git a/src/org/traccar/web/PositionServlet.java b/src/org/traccar/web/PositionServlet.java
index 796d6a81f..c63968251 100644
--- a/src/org/traccar/web/PositionServlet.java
+++ b/src/org/traccar/web/PositionServlet.java
@@ -23,8 +23,9 @@ import org.traccar.model.Position;
 
 import java.util.HashMap;
 import java.util.Map;
+import org.traccar.model.Device;
 
-public class PositionServlet extends BaseServlet {
+public class PositionServlet extends BaseServletResource<Position> {
 
     @Override
     protected boolean handle(String command, HttpServletRequest req, HttpServletResponse resp) throws Exception {
@@ -42,9 +43,10 @@ public class PositionServlet extends BaseServlet {
         return true;
     }
 
-    private void get(HttpServletRequest req, HttpServletResponse resp) throws Exception {
+    @Override
+    protected void get(HttpServletRequest req, HttpServletResponse resp) throws Exception {
         long deviceId = Long.parseLong(req.getParameter("deviceId"));
-        Context.getPermissionsManager().checkDevice(getUserId(req), deviceId);
+        Context.getPermissionsManager().check(Device.class, getUserId(req), deviceId);
         sendResponse(resp.getWriter(), JsonConverter.arrayToJson(
                     Context.getDataManager().getPositions(
                             getUserId(req), deviceId,
@@ -59,7 +61,7 @@ public class PositionServlet extends BaseServlet {
         for (String deviceIdString : req.getParameterValues("devicesId")) {
             Long deviceId = Long.parseLong(deviceIdString);
 
-            Context.getPermissionsManager().checkDevice(userId, deviceId);
+            Context.getPermissionsManager().check(Device.class, userId, deviceId);
 
             Position position = Context.getConnectionManager().getLastPosition(deviceId);
             positions.put(deviceId.toString(), position);
diff --git a/src/org/traccar/web/ServerServlet.java b/src/org/traccar/web/ServerServlet.java
index 7ed096bc6..312876f36 100644
--- a/src/org/traccar/web/ServerServlet.java
+++ b/src/org/traccar/web/ServerServlet.java
@@ -18,16 +18,17 @@ package org.traccar.web;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import org.traccar.Context;
+import org.traccar.helper.CommandCall;
 import org.traccar.model.Server;
 
-public class ServerServlet extends BaseServlet {
+public class ServerServlet extends BaseServletResource<Server> {
 
     @Override
     protected boolean handle(String command, HttpServletRequest req, HttpServletResponse resp) throws Exception {
 
         switch (command) {
             case "/get":
-                get(resp);
+                get(req, resp);
                 break;
             case "/update":
                 update(req, resp);
@@ -38,16 +39,22 @@ public class ServerServlet extends BaseServlet {
         return true;
     }
 
-    private void get(HttpServletResponse resp) throws Exception {
-        sendResponse(resp.getWriter(), JsonConverter.objectToJson(
-                    Context.getDataManager().getServer()));
+    @Override
+    protected void update(HttpServletRequest req, HttpServletResponse resp) throws Exception {
+        super.update(req, resp, new CommandCall() {
+
+            @Override
+            public void check() {
+                Context.getPermissionsManager().checkAdmin(getUserId());
+            }
+
+        });
     }
 
-    private void update(HttpServletRequest req, HttpServletResponse resp) throws Exception {
-        Server server = JsonConverter.objectFromJson(req.getReader(), new Server());
-        Context.getPermissionsManager().checkAdmin(getUserId(req));
-        Context.getDataManager().updateServer(server);
-        sendResponse(resp.getWriter(), true);
+    @Override
+    protected void get(HttpServletRequest req, HttpServletResponse resp) throws Exception {
+        sendResponse(resp.getWriter(), JsonConverter.objectToJson(
+                    Context.getDataManager().getServer()));
     }
 
 }
diff --git a/src/org/traccar/web/UserServlet.java b/src/org/traccar/web/UserServlet.java
index 6bd870d4d..f7ae19fa9 100644
--- a/src/org/traccar/web/UserServlet.java
+++ b/src/org/traccar/web/UserServlet.java
@@ -18,9 +18,10 @@ package org.traccar.web;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import org.traccar.Context;
+import org.traccar.helper.CommandCall;
 import org.traccar.model.User;
 
-public class UserServlet extends BaseServlet {
+public class UserServlet extends BaseServletResource<User> {
 
     @Override
     protected boolean handle(String command, HttpServletRequest req, HttpServletResponse resp) throws Exception {
@@ -44,38 +45,64 @@ public class UserServlet extends BaseServlet {
         return true;
     }
 
-    private void get(HttpServletRequest req, HttpServletResponse resp) throws Exception {
+    @Override
+    protected void get(HttpServletRequest req, HttpServletResponse resp) throws Exception {
         Context.getPermissionsManager().checkAdmin(getUserId(req));
         sendResponse(resp.getWriter(), JsonConverter.arrayToJson(
                     Context.getDataManager().getUsers()));
     }
 
-    private void add(HttpServletRequest req, HttpServletResponse resp) throws Exception {
-        User user = JsonConverter.objectFromJson(req.getReader(), new User());
-        Context.getPermissionsManager().checkUser(getUserId(req), user.getId());
-        Context.getDataManager().addUser(user);
-        Context.getPermissionsManager().refresh();
-        sendResponse(resp.getWriter(), JsonConverter.objectToJson(user));
-    }
+    @Override
+    protected void add(HttpServletRequest req, HttpServletResponse resp) throws Exception {
+        super.add(req, resp, new CommandCall<User>() {
 
-    private void update(HttpServletRequest req, HttpServletResponse resp) throws Exception {
-        User user = JsonConverter.objectFromJson(req.getReader(), new User());
-        if (user.getAdmin()) {
-            Context.getPermissionsManager().checkAdmin(getUserId(req));
-        } else {
-            Context.getPermissionsManager().checkUser(getUserId(req), user.getId());
-        }
-        Context.getDataManager().updateUser(user);
-        Context.getPermissionsManager().refresh();
-        sendResponse(resp.getWriter(), true);
+            @Override
+            public void check() throws Exception {
+                Context.getPermissionsManager().check(User.class, getUserId(), getEntity().getId());
+            }
+
+            @Override
+            public void after() throws Exception {
+                Context.getPermissionsManager().refresh();
+            }
+        });
     }
 
-    private void remove(HttpServletRequest req, HttpServletResponse resp) throws Exception {
-        User user = JsonConverter.objectFromJson(req.getReader(), new User());
-        Context.getPermissionsManager().checkUser(getUserId(req), user.getId());
-        Context.getDataManager().removeUser(user);
-        Context.getPermissionsManager().refresh();
-        sendResponse(resp.getWriter(), true);
+    @Override
+    protected void update(HttpServletRequest req, HttpServletResponse resp) throws Exception {
+        super.update(req, resp, new CommandCall<User>() {
+
+            @Override
+            public void check() {
+                if (getEntity().getAdmin()) {
+                    Context.getPermissionsManager().checkAdmin(getUserId());
+                } else {
+                    Context.getPermissionsManager().check(User.class, getUserId(), getEntity().getId());
+                }
+            }
+
+            @Override
+            public void after() {
+                Context.getPermissionsManager().refresh();
+            }
+
+        });
     }
 
+    @Override
+    protected void remove(HttpServletRequest req, HttpServletResponse resp) throws Exception {
+        super.remove(req, resp, new CommandCall<User>() {
+
+            @Override
+            public void check() throws Exception {
+                Context.getPermissionsManager().check(User.class, getUserId(), getEntity().getId());
+            }
+
+            @Override
+            public void after() throws Exception {
+                Context.getPermissionsManager().refresh();
+            }
+
+        });
+    }
 }
diff --git a/src/org/traccar/web/WebServer.java b/src/org/traccar/web/WebServer.java
index 36c43736d..2e7e1a31b 100644
--- a/src/org/traccar/web/WebServer.java
+++ b/src/org/traccar/web/WebServer.java
@@ -102,10 +102,15 @@ public class WebServer {
         servletHandler.setContextPath("/api");
         servletHandler.addServlet(new ServletHolder(new AsyncServlet()), "/async/*");
         servletHandler.addServlet(new ServletHolder(new ServerServlet()), "/server/*");
+        servletHandler.addServlet(new ServletHolder(new ServerServlet()), "/servers/*");
         servletHandler.addServlet(new ServletHolder(new UserServlet()), "/user/*");
+        servletHandler.addServlet(new ServletHolder(new UserServlet()), "/users/*");
         servletHandler.addServlet(new ServletHolder(new DeviceServlet()), "/device/*");
+        servletHandler.addServlet(new ServletHolder(new DeviceServlet()), "/devices/*");
         servletHandler.addServlet(new ServletHolder(new PositionServlet()), "/position/*");
+        servletHandler.addServlet(new ServletHolder(new PositionServlet()), "/positions/*");
         servletHandler.addServlet(new ServletHolder(new CommandServlet()), "/command/*");
+        servletHandler.addServlet(new ServletHolder(new CommandServlet()), "/commands/*");
         servletHandler.addServlet(new ServletHolder(new MainServlet()), "/*");
         handlers.addHandler(servletHandler);
     }
diff --git a/test/org/traccar/web/JsonConverterTest.java b/test/org/traccar/web/JsonConverterTest.java
index 5b2d80ebc..2a0055f54 100644
--- a/test/org/traccar/web/JsonConverterTest.java
+++ b/test/org/traccar/web/JsonConverterTest.java
@@ -20,7 +20,7 @@ public class JsonConverterTest {
                 "\"string\": \"discworld\", " +
                 "\"date\":\"2015-07-09T19:02:17.000Z\"" +
                 "}"),
-                new Primitives());
+                Primitives.class);
 
         assertEquals(true, o.getBoolean());
         assertEquals(42, o.getInt());