Create an extension

What is extension?

Extension (or plugin) is an android application that integrates with OSSW android application and exposes some properties or allows to invoke some functions.

You can check a source code of sample extension that is available on github

Extension definition

One of the first decisions is to choose a package name for the extension, in the sample plugin it’s:

com.althink.android.ossw.plugins.sample

I will reference this name with %PACKAGE_NAME% placeholder.

Every extension’s AndroidManifest.xml should look like this:

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
 3     package="%PACKAGE_NAME%">
 4 
 5     <application
 6         android:allowBackup="true"
 7         android:icon="@drawable/ic_launcher"
 8         android:label="@string/app_name"
 9         android:theme="@style/AppTheme">
10         <activity
11             android:name=".SamplePluginSettingsActivity"
12             android:label="@string/plugin_name">
13             <intent-filter>
14                 <action android:name="%PACKAGE_NAME%.config" />
15                 <category android:name="android.intent.category.DEFAULT" />
16             </intent-filter>
17         </activity>
18 
19         <provider
20             android:name=".SamplePluginContentProvider"
21             android:authorities="%PACKAGE_NAME%"
22             android:exported="true"
23             android:syncable="false"
24             android:enabled="true"
25             android:label="@string/plugin_name"
26             ><meta-data android:name="com.althink.android.ossw.plugin" android:value="true"></meta-data>
27         </provider>
28 
29         <service
30             android:name=".SamplePluginService"
31             android:exported="true">
32             <intent-filter>
33                 <action android:name="%PACKAGE_NAME%" />
34             </intent-filter>
35         </service>
36     </application>
37 </manifest>

There are three important definitions:

Extension Service

Extension service is a backend service that is responsible for updating extension properties and handling extension function invocations.

The simplest extension service implementation will look like this:

 1 public class SamplePluginService extends Service {
 2     private final Messenger mMessenger = new Messenger(new OperationHandler());
 3 
 4     @Override
 5     public IBinder onBind(Intent intent) {
 6         // perform some initialization
 7         return mMessenger.getBinder();
 8     }
 9     
10     private class OperationHandler extends Handler {
11 
12         public OperationHandler() {
13         }
14 
15         @Override
16         public void handleMessage(Message msg) {
17             super.handleMessage(msg);
18 
19             switch (msg.what) {
20                 // handle function invocation, msg.what contains function identifier
21                 
22                 // optional function parameter can be accessed by invoking:
23                 // String parameter = msg.getData().getString("parameter");
24             }
25         }
26     }
27 }

Extension Content Provider

Extension content provider is a content provider that expose extension API and extension properties (if any). Extension content provider should handle given URIs:

Extension properties

content://%PACKAGE_NAME%/api/properties

Table with definition of extension properties, every row represents single property, table columns are as follows:

Extension functions

content://%PACKAGE_NAME%/api/functions

Table with definition of extension functions, every row represents single function, table columns are as follows:

Extension property values

content://%PACKAGE_NAME%/properties

Table with extension property values, table columns are extension property names and first row values are extension property values. Only one row should be returned.

Extension Settings Activity

Extension settings activity is a standard android PreferenceActivity that is responsible for extension configuration.

Extension settings activity should handle “%PACKAGE_NAME%.config” intent action, for sample extension it’s 

com.althink.android.ossw.plugins.sample.config

Intent filter definition should look like this:

1 <intent-filter>
2     <action android:name="%PACKAGE_NAME%.config" />
3     <category android:name="android.intent.category.DEFAULT" />
4 </intent-filter>