content: /*
   * Copyright (C) 2015 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 android.nfc.cardemulation;
  
  import android.annotation.SdkConstant;
  import android.annotation.SdkConstant.SdkConstantType;
  import android.app.Service;
  import android.content.Intent;
  import android.content.pm.PackageManager;
  import android.os.IBinder;
  
  /**
   * <p>OffHostApduService is a convenience {@link Service} class that can be
   * extended to describe one or more NFC applications that are residing
   * off-host, for example on an embedded secure element or a UICC.
   *
   * <div class="special reference">
   * <h3>Developer Guide</h3>
   * For a general introduction into the topic of card emulation,
   * please read the <a href="{@docRoot}guide/topics/connectivity/nfc/hce.html">
   * NFC card emulation developer guide.</a></p>
   * </div>
   *
   * <h3>NFC Protocols</h3>
   * <p>Off-host applications represented by this class are based on the NFC-Forum ISO-DEP
   * protocol (based on ISO/IEC 14443-4) and support processing
   * command Application Protocol Data Units (APDUs) as
   * defined in the ISO/IEC 7816-4 specification.
   *
   * <h3>Service selection</h3>
   * <p>When a remote NFC device wants to talk to your
   * off-host NFC application, it sends a so-called
   * "SELECT AID" APDU as defined in the ISO/IEC 7816-4 specification.
   * The AID is an application identifier defined in ISO/IEC 7816-4.
   *
   * <p>The registration procedure for AIDs is defined in the
   * ISO/IEC 7816-5 specification. If you don't want to register an
   * AID, you are free to use AIDs in the proprietary range:
   * bits 8-5 of the first byte must each be set to '1'. For example,
   * "0xF00102030405" is a proprietary AID. If you do use proprietary
   * AIDs, it is recommended to choose an AID of at least 6 bytes,
   * to reduce the risk of collisions with other applications that
   * might be using proprietary AIDs as well.
   *
   * <h3>AID groups</h3>
   * <p>In some cases, an off-host environment may need to register multiple AIDs
   * to implement a certain application, and it needs to be sure
   * that it is the default handler for all of these AIDs (as opposed
   * to some AIDs in the group going to another service).
   *
   * <p>An AID group is a list of AIDs that should be considered as
   * belonging together by the OS. For all AIDs in an AID group, the
   * OS will guarantee one of the following:
   * <ul>
   * <li>All AIDs in the group are routed to the off-host execution environment
   * <li>No AIDs in the group are routed to the off-host execution environment
   * </ul>
   * In other words, there is no in-between state, where some AIDs
   * in the group can be routed to this off-host execution environment,
   * and some to another or a host-based {@link HostApduService}.
   * <h3>AID groups and categories</h3>
   * <p>Each AID group can be associated with a category. This allows
   * the Android OS to classify services, and it allows the user to
   * set defaults at the category level instead of the AID level.
   *
   * <p>You can use
   * {@link CardEmulation#isDefaultServiceForCategory(android.content.ComponentName, String)}
   * to determine if your off-host service is the default handler for a category.
   *
   * <p>In this version of the platform, the only known categories
   * are {@link CardEmulation#CATEGORY_PAYMENT} and {@link CardEmulation#CATEGORY_OTHER}.
   * AID groups without a category, or with a category that is not recognized
   * by the current platform version, will automatically be
   * grouped into the {@link CardEmulation#CATEGORY_OTHER} category.
   *
   * <h3>Service AID registration</h3>
   * <p>To tell the platform which AIDs
   * reside off-host and are managed by this service, a {@link #SERVICE_META_DATA}
   * entry must be included in the declaration of the service. An
   * example of a OffHostApduService manifest declaration is shown below:
   * <pre> &lt;service android:name=".MyOffHostApduService" android:exported="true" android:permission="android.permission.BIND_NFC_SERVICE"&gt;
   *     &lt;intent-filter&gt;
   *         &lt;action android:name="android.nfc.cardemulation.action.OFF_HOST_APDU_SERVICE"/&gt;
   *     &lt;/intent-filter&gt;
   *     &lt;meta-data android:name="android.nfc.cardemulation.off_host_apdu_ervice" android:resource="@xml/apduservice"/&gt;
   * &lt;/service&gt;</pre>
   *
   * This meta-data tag points to an apduservice.xml file.
   * An example of this file with a single AID group declaration is shown below:
   * <pre>
   * &lt;offhost-apdu-service xmlns:android="http://schemas.android.com/apk/res/android"
   *           android:description="@string/servicedesc"&gt;
   *       &lt;aid-group android:description="@string/subscription" android:category="other">
   *           &lt;aid-filter android:name="F0010203040506"/&gt;
   *           &lt;aid-filter android:name="F0394148148100"/&gt;
   *       &lt;/aid-group&gt;
   * &lt;/offhost-apdu-service&gt;
   * </pre>
   *
   * <p>The {@link android.R.styleable#OffHostApduService &lt;offhost-apdu-service&gt;} is required
   * to contain a
   * {@link android.R.styleable#OffHostApduService_description &lt;android:description&gt;}
   * attribute that contains a user-friendly description of the service that may be shown in UI.
   *
   * <p>The {@link android.R.styleable#OffHostApduService &lt;offhost-apdu-service&gt;} must
   * contain one or more {@link android.R.styleable#AidGroup &lt;aid-group&gt;} tags.
   * Each {@link android.R.styleable#AidGroup &lt;aid-group&gt;} must contain one or
   * more {@link android.R.styleable#AidFilter &lt;aid-filter&gt;} tags, each of which
   * contains a single AID. The AID must be specified in hexadecimal format, and contain
   * an even number of characters.
   *
   * <p>This registration will allow the service to be included
   * as an option for being the default handler for categories.
   * The Android OS will take care of correctly
   * routing the AIDs to the off-host execution environment,
   * based on which service the user has selected to be the handler for a certain category.
   *
   * <p>The service may define additional actions outside of the
   * Android namespace that provide further interaction with
   * the off-host execution environment.
   *
   * <p class="note">Use of this class requires the
   * {@link PackageManager#FEATURE_NFC_HOST_CARD_EMULATION} to be present
   * on the device.
   */
  public abstract class OffHostApduService extends Service {
      /**
       * The {@link Intent} action that must be declared as handled by the service.
       */
      @SdkConstant(SdkConstantType.SERVICE_ACTION)
      public static final String SERVICE_INTERFACE =
              "android.nfc.cardemulation.action.OFF_HOST_APDU_SERVICE";
  
      /**
       * The name of the meta-data element that contains
       * more information about this service.
       */
      public static final String SERVICE_META_DATA =
              "android.nfc.cardemulation.off_host_apdu_service";
  
      /**
       * The Android platform itself will not bind to this service,
       * but merely uses its declaration to keep track of what AIDs
       * the service is interested in. This information is then used
       * to present the user with a list of applications that can handle
       * an AID, as well as correctly route those AIDs either to the host (in case
       * the user preferred a {@link HostApduService}), or to an off-host
       * execution environment (in case the user preferred a {@link OffHostApduService}.
       *
       * Implementers may define additional actions outside of the
       * Android namespace that allow further interactions with
       * the off-host execution environment. Such implementations
       * would need to override this method.
       */
      public abstract IBinder onBind(Intent intent);
  }
  