Recommendation: Use Amplify clients to connect to AppSync

For front-end web and mobile development, we recommend using the Amplify clients which are optimized to connect to the AppSync backend.

• For DynamoDB data sources, use the DataStore category in the Amplify client. It provides the best developer experience and built-in conflict detection and resolution.
• For non-DynamoDB data sources in scenarios where you have no offline requirements, use the API (GraphQL) category in the Amplify client.

AWS AppSync SDK for Android

The AWS AppSync SDK for Android enables you to access your AWS AppSync backend and perform operations like queries, mutations, and subscription. The SDK also includes support for offline operations. This SDK is derrived from the Apollo project found here. Please log questions for this client SDK in this repo and questions for the AppSync service in the official AWS AppSync forum.

Platform Support

AWS AppSync SDK for Android supports Android API level 21 (Android 5.0) and above.

Samples

1. A sample app using the events sample schema can be found here: https://github.com/aws-samples/aws-mobile-appsync-events-starter-android

Step by step documentation can be found here: https://aws-amplify.github.io/docs/android/api

Setup

Gradle setup

Project's build.gradle

In the project's build.gradle, add a dependency to the dependencies inside the buildscript block:

groovy classpath 'com.amazonaws:aws-android-sdk-appsync-gradle-plugin:3.4.1'

Also, add the maven plugins repository to your repositories.

Do this for the repositories block under buildscript:

groovy buildscript { repositories { // Add this maven block. maven { url "https://plugins.gradle.org/m2/" } google() mavenCentral() } }

And also under allprojects, too:

groovy allprojects { repositories { // Add this maven block. maven { url "https://plugins.gradle.org/m2/" } google() mavenCentral() } }

Sample project's build.gradle

```groovy // Top-level build file where you can add configuration options common to all sub-projects/modules. buildscript { repositories { maven { url "https://plugins.gradle.org/m2/" } google() mavenCentral() }

dependencies {
    classpath 'com.android.tools.build:gradle:3.5.3'
    classpath 'com.amazonaws:aws-android-sdk-appsync-gradle-plugin:3.4.1'
}

}

allprojects { repositories { maven { url "https://plugins.gradle.org/m2/" } google() mavenCentral() } }

... other stuff ... ```

App's build.gradle

In the app's build.gradle, add the following plugin:

groovy apply plugin: 'com.amazonaws.appsync'

Add the following dependency:

groovy implementation 'com.amazonaws:aws-android-sdk-appsync:3.4.1'

Sample app's build.gradle

```groovy apply plugin: 'com.android.application' apply plugin: 'com.amazonaws.appsync'

android { // Typical items }

dependencies { // Typical dependencies implementation 'com.amazonaws:aws-android-sdk-appsync:3.4.1' } ```

App's AndroidManifest.xml

To determine if the device is offline, add permissions to access the network state:

xml <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

Code generation

To interact with AppSync, your client needs to define GraphQL queries and mutations.

For example, create a file named ./app/src/main/graphql/com/amazonaws/demo/posts/posts.graphql:

```graphql query GetPost($id:ID!) { getPost(id:$id) { id title author content url version } }

mutation AddPost($id: ID!, $author: String!, $title: String, $content: String, $url: String, $ups: Int!, $downs: Int!, $expectedVersion: Int!) { putPost(id: $id, author: $author, title: $title, content: $content, url: $url, ups: $ups, downs: $downs, version: $expectedVersion) { id title author url content } } ```

Next, fetch the schema.json file from the AppSync console and place it alongside the posts.graphql file: console ./app/src/main/graphql/com/amazonaws/demo/posts/schema.json

Now build the project and the generated source files will be available to use within the app. They will not show up in your source directory, but are added in the build path.

Create a client

Configuration via code

java AWSAppSyncClient client = AWSAppSyncClient.builder() .context(context) .apiKey(new BasicAPIKeyAuthProvider(Constants.APPSYNC_API_KEY)) // API Key based authorization .region(Constants.APPSYNC_REGION) .serverUrl(Constants.APPSYNC_API_URL) .build();

Configuration via a config file

Alternatively, you can use the awsconfiguration.json file to supply the configuration information required to create a AWSAppSyncClient object.

Create a file named awsconfiguration.json under your app's res/raw directory.

json { "AppSync": { "Default": { "ApiUrl": "YOUR-GRAPHQL-ENDPOINT", "Region": "us-east-1", "ApiKey": "YOUR-API-KEY", "AuthMode": "API_KEY" } } }

The AWSConfiguration represents the configuration information present in awsconfiguration.json file. By default, the information under Default section will be used.

java AWSAppSyncClient client = AWSAppSyncClient.builder() .context(context) .awsConfiguration(new AWSConfiguration(context)) .build();

You can override the Default configuration by using the AWSConfiguration#setConfiguration() method.

json { "AppSync": { "Default": { "ApiUrl": "YOUR-GRAPHQL-ENDPOINT", "Region": "us-east-1", "ApiKey": "YOUR-API-KEY", "AuthMode": "API_KEY" }, "Custom": { "ApiUrl": "YOUR-GRAPHQL-ENDPOINT", "Region": "us-east-2", "ApiKey": "YOUR-API-KEY", "AuthMode": "API_KEY" } } }

```java AWSConfiguration awsConfig = new AWSConfiguration(context); awsConfig.setConfiguration("Custom");

AWSAppSyncClient client = AWSAppSyncClient.builder() .context(context) .awsConfiguration(awsConfig) .build(); ```

Authentication Modes

When making calls to AWS AppSync, there are several ways to authenticate those calls. API key authorization (API_KEY) is the simplest way to onboard. After onboarding, we recommend you use one of the other modes:

1. Amazon IAM (AWS_IAM)
2. Amazon Cognito UserPools (AMAZON_COGNITO_USER_POOLS)
3. Any OpenID Connect Provider (OPENID_CONNECT)

API Key

For authorization using the API key, update the awsconfiguration.json file and code snippet as follows:

Configuration

Add the following snippet to your awsconfiguration.json file.

json { "AppSync": { "Default": { "ApiUrl": "YOUR-GRAPHQL-ENDPOINT", "Region": "us-east-1", "ApiKey": "YOUR-API-KEY", "AuthMode": "API_KEY" } } }

Code

In order to use the information in the Default section from awsconfiguration.json file, add the following code:

java AWSAppSyncClient client = AWSAppSyncClient.builder() .context(context) .awsConfiguration(new AWSConfiguration(context)) .build();

AWS IAM

For authorization using Amazon IAM credentials, using Amazon IAM or Amazon STS or Amazon Cognito, update the awsconfiguration.json file and code snippet as follows:

Configuration

Add the following snippet to your awsconfiguration.json file.

json { "CredentialsProvider": { "CognitoIdentity": { "Default": { "PoolId": "YOUR-COGNITO-IDENTITY-POOLID", "Region": "us-east-1" } } }, "AppSync": { "Default": { "ApiUrl": "YOUR-GRAPHQL-ENDPOINT", "Region": "us-east-1", "AuthMode": "AWS_IAM" } } }

Code

Add the following code to use the information in the Default section from awsconfiguration.json file.

```java AWSConfiguration awsConfig = new AWSConfiguration(context);

CognitoCachingCredentialsProvider credentialsProvider = new CognitoCachingCredentialsProvider(context, awsConfig);

AWSAppSyncClient client = AWSAppSyncClient.builder() .context(context) .awsConfiguration(awsConfig) .credentialsProvider(credentialsProvider) .build(); ```

Amazon Cognito UserPools

For authorization using the Amazon Cognito UserPools, update the awsconfiguration.json file and code snippet as follows:

Configuration

Add the following snippet to your awsconfiguration.json file.

{ "CognitoUserPool": { "Default": { "PoolId": "POOL-ID", "AppClientId": "APP-CLIENT-ID", "AppClientSecret": "APP-CLIENT-SECRET", "Region": "us-east-1" } }, "AppSync": { "Default": { "ApiUrl": "YOUR-GRAPHQL-ENDPOINT", "Region": "us-east-1", "AuthMode": "AMAZON_COGNITO_USER_POOLS" } } }

Code

Add the following dependency to your app in order to use Amazon Cognito UserPools:

groovy dependencies { implementation 'com.amazonaws:aws-android-sdk-cognitoidentityprovider:2.16.12' }

Add the following code to use the information in the Default section from awsconfiguration.json file.

```java AWSConfiguration awsConfig = new AWSConfiguration(context);

CognitoUserPool cognitoUserPool = new CognitoUserPool(context, awsConfig); BasicCognitoUserPoolsAuthProvider basicCognitoUserPoolsAuthProvider = new BasicCognitoUserPoolsAuthProvider(cognitoUserPool);

AWSAppSyncClient awsAppSyncClient = AWSAppSyncClient.builder() .context(context) .awsConfiguration(awsConfig) .cognitoUserPoolsAuthProvider(basicCognitoUserPoolsAuthProvider) .build(); ```

OIDC (OpenID Connect)

For authorization using any OIDC (OpenID Connect) Identity Provider, update the awsconfiguration.json file and code snippet as follows:

Configuration

Add the following snippet to your awsconfiguration.json file.

{ "AppSync": { "Default": { "ApiUrl": "YOUR-GRAPHQL-ENDPOINT", "Region": "us-east-1", "AuthMode": "OPENID_CONNECT" } } }

Code

Add the following code to use the information in the Default section from awsconfiguration.json file.

java AWSAppSyncClient client = AWSAppSyncClient.builder() .context(context) .awsConfiguration(new AWSConfiguration(context)) .oidcAuthProvider(() -> "jwt-token-from-oidc-provider") .build();

Make a call

```java public void addPost() { GraphQLCall.Callback postsCallback = new GraphQLCall.Callback<>() { @Override public void onResponse(Response response) { // Called on a non-UI thread runOnUiThread(() -> { /* do stuff on UI thread */ }); }

    @Override
    public void onFailure(ApolloException failure) {
        // Error handling
    }
};

AddPostMutation addPostMutation = AddPostMutation.builder()
    .id(UUID.randomUUID().toString())
    .title(title)
    .author(author)
    .url(url)
    .content(content)
    .ups(0)
    .downs(0)
    .expectedVersion(1)
    .build();

client.mutate(addPostMutation).enqueue(postsCallback);

} ```

License

This library is licensed under the Apache License 2.0.