Android DDP Client library to implement native client for Meteor.js server
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README.md

Meteor.js Android DDP Client

This library is an Android layer that builds on top of the Java DDP Client.
It contains an Android-specific DDP state layer that makes it easier to develop a Meteor.js Android native client.

On Android, instead of using the Java Observer/Listener pattern of the Java DDP client, a better design pattern is the publish/subscribe event pattern because of how UI handling works. You can do this w/ the native LocalBroadcastManager from the V4 Support Library, or you can use 3rd party event libraries like [GreenRobot's EventBus][https://github.com/greenrobot/EventBus], [Square's Otto][https://github.com/square/otto], or [Mike Burton's RoboGuice][https://github.com/roboguice/roboguice] (which has event handling as part of its Dependency Injection support). This library uses LocalBroadcastManager but this behavior can be overridden.

The local Meteor collections are managed in this base implementation as Map<String,Object> document collections.
This behavior can be overridden so you can store data into SQLite.

The MeteorPartiesDDPClient is an example of how to use this library.

Usage

In Eclipse or Android Studio, import the Java DDP Client library into your project (you'll also need the Eclipse Gradle plugin installed) and then import this library. Add the Java DDP Client library to your build path. Once these build, you can add this library to your Android app's library references. If you don't need this, you can just add the javaddpclient.jar and androidddpclient.aar into your Android app's project.
If you use gradle for builds, you'll see an error message in Eclipse for your project until you clean the project.

Once you do that, you can create a class that extends DDPStateSingleton that will handle your objects. This example is from the Meteor Parties sample app:

public class MyDDPState extends DDPStateSingleton {
...
    @Override
    protected void broadcastSubscriptionChanged(String collectionName,
        String changetype, String docId) {
        if (collectionName.equals("parties")) {
            if (changetype.equals(DdpMessageType.ADDED)) {
                mParties.put(docId, new Party(docId, (Map<String, Object>) getCollection(collectionName).get(docId)));
            } else if (changetype.equals(DdpMessageType.REMOVED)) {
                mParties.remove(docId);
            } else if (changetype.equals(DdpMessageType.UPDATED)) {
                mParties.get(docId).refreshFields();
            }
        }
        // do the broadcast after we've taken care of our parties wrapper
        super.broadcastSubscriptionChanged(collectionName, changetype, docId);
    }
...
}

If you want to use your own data store, you should override the following methods in MyDDPState: addDoc, updateDoc, removeDoc, and getUserEmail (the get user email command has to look through your users collection to translate a user ID to an email address). These methods are in the DDPStateStorage interface. You don't have to override getCollection and getDocument because you'll need to return what's appropriate for your data store (objects, etc).

If you want to use your own event system, you should override the following methods in MyDDPState: broadcastConnectionState, broadcastDDPError, and broadcastSubscriptionChanged. These methods are in the DDPStateBroadcasts interface.

In each of your activities that needs to display "live" data, you'll need to hook in an event/broadcast receiver to receive the broadcasts and this can be done in the OnResume method. If you're using a custom event bus, you have to handle the error, connection state, and document update events. Here's an example from a Login Activity:

protected void onResume() {
    super.onResume();
    mReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            // display errors to the user
            Bundle bundle = intent.getExtras();
            showProgress(false);
            if (intent.getAction().equals(MyDDPState.MESSAGE_ERROR)) {
                String message = bundle.getString(MyDDPState.MESSAGE_EXTRA_MSG);
                showError("Login Error", message);
            } else if (intent.getAction().equals(MyDDPState.MESSAGE_CONNECTION)) {
                int state = bundle.getInt(MyDDPState.MESSAGE_EXTRA_STATE);
                if (state == MyDDPState.DDPSTATE.LoggedIn.ordinal()) {
                    // login complete, so we can close this login activity and go back
                    finish();
                }
            }
        }

    };
    // we want error messages
    LocalBroadcastManager.getInstance(this).registerReceiver(mReceiver,
            new IntentFilter(MyDDPState.MESSAGE_ERROR));
    // we want connection state change messages so we know we're logged in
    LocalBroadcastManager.getInstance(this).registerReceiver(mReceiver,
            new IntentFilter(MyDDPState.MESSAGE_CONNECTION));
}

Remember to unhook the receiver when the activity is suspended in OnPause:

protected void onPause() {
    super.onPause();             
    if (mReceiver != null) {
        LocalBroadcastManager.getInstance(this).unregisterReceiver(mReceiver);
        mReceiver = null;
    }
}

Maven Artifact

This library is in the Maven Central Library hosted by Sonatype. In Gradle, you can reference it with this in your dependencies:

compile group: 'com.keysolutions', name: 'android-ddp-client', version: '1.0.2.+'

And in Maven, you can reference it with this:

<dependency>
  <groupId>com.keysolutions</groupId>
  <artifactId>android-ddp-client</artifactId>
  <version>1.0.2.0</version>
  <type>pom</type>
</dependency>

The version of the library supports DDP protocol version 1.0 (handled by java-ddp-client library).

  • 0.5.7.1 uses com.google.android:support-v4:r7
  • 0.5.7.2 uses com.android.support:support-v4:13.0.+ and adds getDocument() method
  • 0.5.7.3 fix Maven dynamic version syntax
  • 0.5.7.4 didn't use subscription parameter in ddpstatesingleton
  • 0.5.7.6 fix handling of add/delete field (skipped version 0.5.7.6 to match java-ddp-client update)
  • 1.0.0.0 update to latest libraries and match java-ddp-client version w/ ping/pong support; merge pull requests
  • 1.0.1.0 merge in Jasper's Facebook login support
  • 1.0.2.0 add missing Closed broadcast notification; add SSL support; add logout; update to Android Studio

To-Do

  • Move JUnit tests from java-ddp-client to this library?
  • Review DDPStateSingleton inheritance...it'd be a lot cleaner if Java supported multiple inheritance or C#'s partial classes.