Quick Start

This tutorial provides a quick introduction to set up MultiCloudJ dependency and write a multi-cloud application with blobstore and docstore interface.

1. Add maven Dependencies

Each service have a $service-client such as blob-client artifact as well $service-$provider artifact such blob-aws. The $service-client is MUST HAVE at the build time and your application code uses this to write the code. The $service-$provider is required at the run time, and you can have dependencies for one or multiple providers at the same time. For example, you can have blob-aws, blob-gcp in your dependencies in your classpath at runtime and you can choose the provider during the client initialization.

Add MultiCloudJ blob and docstore dependencies to your Maven project:

<dependency>
    <groupId>com.salesforce.multicloudj</groupId>
    <artifactId>blob-client</artifactId>
    <version>0.2.2</version>
</dependency>
<dependency>
    <groupId>com.salesforce.multicloudj</groupId>
    <artifactId>blob-aws</artifactId>
    <version>0.2.2</version>
</dependency>
<dependency>
    <groupId>com.salesforce.multicloudj</groupId>
    <artifactId>blob-gcp</artifactId>
    <version>0.2.2</version>
</dependency>

Or for Gradle:

implementation 'com.salesforce.multicloudj:blob-client:0.2.2'
implementation 'com.salesforce.multicloudj:blob-aws:0.2.2'
implementation 'com.salesforce.multicloudj:blob-gcp:0.2.2'

2. Set Up AWS Credentials

First, you need to configure AWS credentials on your machine. You have several options:

Follow https://docs.aws.amazon.com/cli/v1/userguide/cli-chap-configure.html To get started, You can have AWS credentials on environment variables or the ~/.aws/credentials file.

3. Create an S3 Bucket

You can create a bucket using the AWS Console, AWS CLI, or programmatically:

# Using AWS CLI
aws s3 mb s3://my-multicloudj-bucket --region us-west-2

4. Your First MultiCloudJ Application

Now let’s create a simple application that connects to your bucket and performs basic operations:

import com.salesforce.multicloudj.blob.client.BucketClient;
import com.salesforce.multicloudj.blob.driver.UploadRequest;
import com.salesforce.multicloudj.blob.driver.DownloadRequest;

public class MultiCloudJQuickStart {
    public static void main(String[] args) {
        // Initialize a session to your S3 bucket
        BucketClient bucketClient = BucketClient.builder("aws")
            .withRegion("us-west-2")  // Replace with your region
            .withBucket("my-multicloudj-bucket")  // Replace with your bucket name
            .build();
        
        try {
            // Upload a blob
            System.out.println("Uploading blob...");
            UploadRequest uploadRequest = new UploadRequest("hello.txt");
            bucketClient.upload(uploadRequest, "Hello, MultiCloudJ!".getBytes());
            System.out.println("Upload successful!");
            
            // Download the blob
            System.out.println("Downloading blob...");
            DownloadRequest downloadRequest = new DownloadRequest("hello.txt");
            byte[] content = bucketClient.download(downloadRequest);
            System.out.println("Downloaded content: " + new String(content));
            
            // List all blobs in the bucket
            System.out.println("Listing blobs in bucket...");
            bucketClient.listBlobs().forEach(blob -> 
                System.out.println("Found blob: " + blob.getKey() + " (size: " + blob.getSize() + " bytes)")
            );
            
        } catch (Exception e) {
            System.err.println("Error: " + e.getMessage());
            e.printStackTrace();
        }
    }
}

5. Run Your Application (If you have IDE that’s better) 

# Compile and run
javac -cp ".:multicloudj-blob-0.2.2.jar" MultiCloudJQuickStart.java
java -cp ".:multicloudj-blob-0.2.2.jar" MultiCloudJQuickStart

6. What Just Happened?

  1. BucketClient Creation: We created a BucketClient instance that connects to your S3 bucket
  2. Upload: We uploaded a simple text file with the content “Hello, MultiCloudJ!”
  3. Download: We downloaded the same file and displayed its content
  4. List: We listed all objects in your bucket to see what’s there

Next Steps

Getting Help

MultiCloudJ is maintained by the Salesforce MultiCloudJ team and is open source under the Apache License 2.0.