Android - Cloudant NoSQL DB API
This tutorial shows how to apply technology available in IBM MobileFirst Platform Foundation to store data for Android mobile applications. By using Cloudant NoSQL DB APIs, you can complete specific database operations, such as creating, reading, updating, deleting, and synchronizing data between local and remote databases. This tutorial provides a basic overview of these APIs and explains how to configure and run the sample, in the following topics:
- Using the IMFData SDK
- Creating local data stores
- Creating remote data stores
- Setting user permissions for remote stores
- Modeling data for Android applications
- Creating and updating data
- Supporting synchronization and offline storage
- Running the Android sample
- Obtaining and configuring the required SDKs
- BlueList application flow
Using the IMFData SDK
After the IMFData SDK is installed, you can begin to initialize and use the SDK in your native Android application.
The value for
cloudantProxyUrl is the URL of the MobileFirst Data Proxy which was configured during installation. The URL includes the IP address, host, and context root that you have defined.
In the native Android sample that comes with this tutorial, the value for the
cloudantProxyUrl is set in the
Creating local data stores
You can create a Store object to allow your application to access a local database, which can be used even when the application is offline.
Creating remote data stores
You can also create a Store object to allow your application to access a remote database.
Setting user permissions for remote stores
You can set specific permissions for users to access remote stores.
Note: In the sample, the user is authenticated via OAuth. OAuth has been configured through adapter-based authentication. You can find further instructions on setting up access with OAuth capabilities and the MobileFirst Data Proxy in configuring OAuth security, in the user documentation.
Modeling data for Android applications
In Android applications, you can use the
DataObjectMapper class to map native objects to JSON document format. When you create a data store with the
DataManager API, you can create a new
DataObjectMapper to set on the
In the sample, a custom
TodoItem class allows you to store custom data as objects in our application. When creating a custom
DataObjectMapper class, make sure that it meets the following requirements:
- Conform to the IMFDataObject protocol.
- Have the IMFDataObject protocol metadata property set on the class interface.
TodoItem implementation (
You must then register the class and data type with the
DataObjectMapper. In the sample, the
DataStoreManager instance does that after the store is created.
Creating and updating data
Using the same operation, you can save new objects and save changes to existing objects in the local data store.
Creating, saving, and updating Todo Items
Note: When saving an object, it is good practice to use the new object that is returned by the
task.getResult() method, to avoid errors caused by stale objects and to maintain a consistent experience.
To delete an object in a data store, pass the object to the LocalStore.delete(objecttodelete) method.
You can query for objects that have an object mapper. To run a query for objects, create a Cloudant query with the query filters on data type. Run the query against a Store object. For more information about query and related operations, see the topics about querying, in the user documentation.
Supporting synchronization and offline storage
By using the data manager API, you can synchronize data between local storage on the device and remote store instances.
When pull replication runs, the local database within the mobile device is updated with what exists in the remote database.
When push replication runs, the data from the local database within the mobile device is sent to the remote database.
Note: The code snippets above might be different from the code that you can see in the sample. These snippets have been created to give the clearest and most understandable outline of the APIs and how they are used. For the sample to be easier to use, all the implementation for the above operations can be found in
Running the Android sample
Make sure that you have properly configured and started the following instances:
- MobileFirst Server with
AndroidBlueListNative API deployed
- Cloudant Data Local Layer Edition
- MobileFirst Data Proxy Server configured against MobileFirst Server and the Cloudant Data Layer Local Edition
Obtaining and configuring the required SDKs
Make sure that you have correctly installed and set up Gradle. If you have not done so, complete the following:
- Download the current Gradle distribution from
- When importing the sample, select a
- Point to the Gradle distribution that you just downloaded.
- After the project is open, check and update the following items:
- In the
bluelist.propertiesfile, set the
cloudantProxyUrlto your MobileFirst Data Proxy Server location.
- In the
wlclient.propertiesfile, make sure to check and update the values to match the MobileFirst Server instance that you have deployed.
- In the
Android Studio then prompts you for a
Now, you can run the sample on the simulators provided by Android or a supported Android device.
BlueList application flow
When the application starts, the
DataStoreManager instance initiates the connection to the MobileFirst Server instance and creates and registers the
For simplicity, the sample silently logs in a user by calling
CloudantAuthenticationAdapter with correct user name and password parameters. This is completed in the
After authentication, the database is configured in the
init method. This database configuration consists of the following steps:
- Initializing the SDK
- Creating the local and remote databases
- Setting permissions for the user that was created
- Setting the
- Registering the
TodoItemclass and data type with the
Note: For simplicity, the database name that is created is currently set to the variable
DBName in the
DataStoreManager, but you can change this name in the
MainActivity class provides functions for creating, updating, deleting, and listing items, and functions for push and pull replication.
After completing initialization, the application does an initial pull from the remote database. The user can now create, update, and modify list items in the application, and modify the corresponding priority (red = high, yellow = medium, white = low). By design, the application starts synchronization only when the user manually pulls down the list. On pull down, the application first completes a pull replication from the remote database to the local. After this operation has completed, push replication occurs, which sends any updated local data to the remote database. The local and remote databases are then synchronized.