Most enterprises use devices that are customized for their requirement. For example having a custom android device that functions as a POS. In such situations organizations prefer to have and maintain custom firmwares or get device vendors to build a custom device to suite their requirement. For example apps or devices having the capability to sign their POS app with the vendor firmware signing key and install it on devices as a system app.
WSO2 EMM provides a separate service application that can be signed by a firmware signing key and installed on the devices as a system application alongside the EMM Agent application. This enables you to have better control over the devices registered with WSO2 EMM. Since this is a system app it provides system level capabilities, such as device firmware upgrade, reboot and enforcing security policies, and much more.
For more information on managing the system service Android application see the following subsections:
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Securing Communication
When the system service app is installed on a device that is registered with WSO2 EMM, the EMM Android Agent communicates with it to trigger system level operations from the WSO2 EMM server. The communication between the system service application and the Android agent is secured by two layers of protection as shown below:
Via the signature - The system will grant permission only if the requesting application is signed with the same certificate as the application that is declared in the permission.
Info For more information on securing the communication, see <permissions> on the Android Developer documents.
- Check the package name of the intent who makes the call to verify that it’s a request from the EMM Anroid agent.
Integrating WSO2 EMM and the system service application
Follow the steps given below to integrate the system service Android application with WSO2 EMM:
- Build the system service application.
- Download the source code.
- The system service app can not be built via the usual android developer SDK, as it requires access to developer restricted APIs. Therefore, you need to replace the existing
android.jarfile that is under the<SDK_LOCATION>/platforms/android-<COMPILE_SDK_VERSION>directory with the explicitly builtandroid.jarfile that has access to the restricted APIs. Use the method given below:- Download the Android Open Source Project (AOSP) and build the source code to get the
jarfile for the required SDK level.
- Download the Android Open Source Project (AOSP) and build the source code to get the
- Open the system service application source code via Android Studio and clean build it as a usual android application.
Sign the system service.
Sign the application via the device firmware signing key. If you don’t have access to the firmware signing key, you have to get the system application signed via your device vendor.Info For more information of singing the system service, see Signing Your Applications.
Install the system service application by following any of the methods given below:
The system service application will be available out of the box with your firmware distribution, if you have your own firmware.
Copy the signed system service APK file to the
/system/priv-appsdirectory of the device.When the device boots or restarts for the first time, it will automatically install the application as a system application.
Install the system service application externally via an Android Debug Bridge command.
Info For more information on how this takes place on WSO2 EMM, see Configuring the WSO2 EMM service application
- Enable the system service invocations through the WSO2 EMM Agent application
Navigate to the
Constants.javaclass, which is in theorg.wso2.emm.agent.utilspackage and configure theSYSTEM_APP_ENABLEDfield as follows:Code Block public static final boolean SYSTEM_APP_ENABLED = true;
- Rebuild the EMM agent application.
Operations supported via the system service application
The following operations are supported via the system service application:
Device Reboot
Info For more information on the device reboot REST API command, see Rebooting Android Devices.
Firmware upgrade
Info For more information on the firmware upgrade REST API command, see Upgrading Firmware of Android Devices via the REST API.
Enforcing user restrictions
Info For more information on the enforcing user restriction via the REST API, see Adding a User Restriction Policy on Android Devices.
Silent app installation, removal and update
Application installation, removal and update will be performed without user confirmation when Android system service is present available on an Android device.Info For more information on silent app installation/removal via the REST API, see Silent install/removal of Applications Installing an Application on Android devicesDevices.