content: /*
   * Copyright (C) 2010 The Android Open Source Project
   *
   * 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 com.google.android.vending.licensing;
  
  /**
   * Allows the developer to limit the number of devices using a single license.
   * <p>
   * The LICENSED response from the server contains a user identifier unique to
   * the &lt;application, user&gt; pair. The developer can send this identifier
   * to their own server along with some device identifier (a random number
   * generated and stored once per application installation,
   * {@link android.telephony.TelephonyManager#getDeviceId getDeviceId},
   * {@link android.provider.Settings.Secure#ANDROID_ID ANDROID_ID}, etc).
   * The more sources used to identify the device, the harder it will be for an
   * attacker to spoof.
   * <p>
   * The server can look at the &lt;application, user, device id&gt; tuple and
   * restrict a user's application license to run on at most 10 different devices
   * in a week (for example). We recommend not being too restrictive because a
   * user might legitimately have multiple devices or be in the process of
   * changing phones. This will catch egregious violations of multiple people
   * sharing one license.
   */
  public interface DeviceLimiter {
  
      /**
       * Checks if this device is allowed to use the given user's license.
       *
       * @param userId the user whose license the server responded with
       * @return LICENSED if the device is allowed, NOT_LICENSED if not, RETRY if an error occurs
       */
      int isDeviceAllowed(String userId);
  }
  