There are more AWS SDK examples available in the [AWS Doc SDK Examples](https://github.com/awsdocs/aws-doc-sdk-examples) GitHub repo.

# Amazon S3 examples using SDK for Kotlin
<a name="kotlin_1_s3_code_examples"></a>

The following code examples show you how to perform actions and implement common scenarios by using the AWS SDK for Kotlin with Amazon S3.

*Basics* are code examples that show you how to perform the essential operations within a service.

*Actions* are code excerpts from larger programs and must be run in context. While actions show you how to call individual service functions, you can see actions in context in their related scenarios.

*Scenarios* are code examples that show you how to accomplish specific tasks by calling multiple functions within a service or combined with other AWS services.

Each example includes a link to the complete source code, where you can find instructions on how to set up and run the code in context.

**Topics**
+ [Basics](#basics)
+ [Actions](#actions)
+ [Scenarios](#scenarios)

## Basics
<a name="basics"></a>

### Learn the basics
<a name="s3_Scenario_GettingStarted_kotlin_1_topic"></a>

The following code example shows how to:
+ Create a bucket and upload a file to it.
+ Download an object from a bucket.
+ Copy an object to a subfolder in a bucket.
+ List the objects in a bucket.
+ Delete the bucket objects and the bucket.

**SDK for Kotlin**  
 There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/kotlin/services/s3#code-examples). 

```
suspend fun main(args: Array<String>) {
    val usage = """
    Usage:
        <bucketName> <key> <objectPath> <savePath> <toBucket>

    Where:
        bucketName - The Amazon S3 bucket to create.
        key - The key to use.
        objectPath - The path where the file is located (for example, C:/AWS/book2.pdf).   
        savePath - The path where the file is saved after it's downloaded (for example, C:/AWS/book2.pdf).     
        toBucket - An Amazon S3 bucket to where an object is copied to (for example, C:/AWS/book2.pdf). 
        """

    if (args.size != 4) {
        println(usage)
        exitProcess(1)
    }

    val bucketName = args[0]
    val key = args[1]
    val objectPath = args[2]
    val savePath = args[3]
    val toBucket = args[4]

    // Create an Amazon S3 bucket.
    createBucket(bucketName)

    // Update a local file to the Amazon S3 bucket.
    putObject(bucketName, key, objectPath)

    // Download the object to another local file.
    getObjectFromMrap(bucketName, key, savePath)

    // List all objects located in the Amazon S3 bucket.
    listBucketObs(bucketName)

    // Copy the object to another Amazon S3 bucket
    copyBucketOb(bucketName, key, toBucket)

    // Delete the object from the Amazon S3 bucket.
    deleteBucketObs(bucketName, key)

    // Delete the Amazon S3 bucket.
    deleteBucket(bucketName)
    println("All Amazon S3 operations were successfully performed")
}

suspend fun createBucket(bucketName: String) {
    val request =
        CreateBucketRequest {
            bucket = bucketName
        }

    S3Client.fromEnvironment { region = "us-east-1" }.use { s3 ->
        s3.createBucket(request)
        println("$bucketName is ready")
    }
}

suspend fun putObject(
    bucketName: String,
    objectKey: String,
    objectPath: String,
) {
    val metadataVal = mutableMapOf<String, String>()
    metadataVal["myVal"] = "test"

    val request =
        PutObjectRequest {
            bucket = bucketName
            key = objectKey
            metadata = metadataVal
            this.body = Paths.get(objectPath).asByteStream()
        }

    S3Client.fromEnvironment { region = "us-east-1" }.use { s3 ->
        val response = s3.putObject(request)
        println("Tag information is ${response.eTag}")
    }
}

suspend fun getObjectFromMrap(
    bucketName: String,
    keyName: String,
    path: String,
) {
    val request =
        GetObjectRequest {
            key = keyName
            bucket = bucketName
        }

    S3Client.fromEnvironment { region = "us-east-1" }.use { s3 ->
        s3.getObject(request) { resp ->
            val myFile = File(path)
            resp.body?.writeToFile(myFile)
            println("Successfully read $keyName from $bucketName")
        }
    }
}

suspend fun listBucketObs(bucketName: String) {
    val request =
        ListObjectsRequest {
            bucket = bucketName
        }

    S3Client.fromEnvironment { region = "us-east-1" }.use { s3 ->

        val response = s3.listObjects(request)
        response.contents?.forEach { myObject ->
            println("The name of the key is ${myObject.key}")
            println("The owner is ${myObject.owner}")
        }
    }
}

suspend fun copyBucketOb(
    fromBucket: String,
    objectKey: String,
    toBucket: String,
) {
    var encodedUrl = ""
    try {
        encodedUrl = URLEncoder.encode("$fromBucket/$objectKey", StandardCharsets.UTF_8.toString())
    } catch (e: UnsupportedEncodingException) {
        println("URL could not be encoded: " + e.message)
    }

    val request =
        CopyObjectRequest {
            copySource = encodedUrl
            bucket = toBucket
            key = objectKey
        }
    S3Client.fromEnvironment { region = "us-east-1" }.use { s3 ->
        s3.copyObject(request)
    }
}

suspend fun deleteBucketObs(
    bucketName: String,
    objectName: String,
) {
    val objectId =
        ObjectIdentifier {
            key = objectName
        }

    val delOb =
        Delete {
            objects = listOf(objectId)
        }

    val request =
        DeleteObjectsRequest {
            bucket = bucketName
            delete = delOb
        }

    S3Client.fromEnvironment { region = "us-east-1" }.use { s3 ->
        s3.deleteObjects(request)
        println("$objectName was deleted from $bucketName")
    }
}

suspend fun deleteBucket(bucketName: String?) {
    val request =
        DeleteBucketRequest {
            bucket = bucketName
        }
    S3Client.fromEnvironment { region = "us-east-1" }.use { s3 ->
        s3.deleteBucket(request)
        println("The $bucketName was successfully deleted!")
    }
}
```
+ For API details, see the following topics in *AWS SDK for Kotlin API reference*.
  + [CopyObject](https://sdk.amazonaws.com/kotlin/api/latest/index.html)
  + [CreateBucket](https://sdk.amazonaws.com/kotlin/api/latest/index.html)
  + [DeleteBucket](https://sdk.amazonaws.com/kotlin/api/latest/index.html)
  + [DeleteObjects](https://sdk.amazonaws.com/kotlin/api/latest/index.html)
  + [GetObject](https://sdk.amazonaws.com/kotlin/api/latest/index.html)
  + [ListObjectsV2](https://sdk.amazonaws.com/kotlin/api/latest/index.html)
  + [PutObject](https://sdk.amazonaws.com/kotlin/api/latest/index.html)

## Actions
<a name="actions"></a>

### `CopyObject`
<a name="s3_CopyObject_kotlin_1_topic"></a>

The following code example shows how to use `CopyObject`.

**SDK for Kotlin**  
 There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/kotlin/services/s3#code-examples). 

```
suspend fun copyBucketObject(
    fromBucket: String,
    objectKey: String,
    toBucket: String,
) {
    var encodedUrl = ""
    try {
        encodedUrl = URLEncoder.encode("$fromBucket/$objectKey", StandardCharsets.UTF_8.toString())
    } catch (e: UnsupportedEncodingException) {
        println("URL could not be encoded: " + e.message)
    }

    val request =
        CopyObjectRequest {
            copySource = encodedUrl
            bucket = toBucket
            key = objectKey
        }
    S3Client.fromEnvironment { region = "us-east-1" }.use { s3 ->
        s3.copyObject(request)
    }
}
```
+  For API details, see [CopyObject](https://sdk.amazonaws.com/kotlin/api/latest/index.html) in *AWS SDK for Kotlin API reference*. 

### `CreateBucket`
<a name="s3_CreateBucket_kotlin_1_topic"></a>

The following code example shows how to use `CreateBucket`.

**SDK for Kotlin**  
 There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/kotlin/services/s3#code-examples). 

```
suspend fun createNewBucket(bucketName: String) {
    val request =
        CreateBucketRequest {
            bucket = bucketName
        }

    S3Client.fromEnvironment { region = "us-east-1" }.use { s3 ->
        s3.createBucket(request)
        println("$bucketName is ready")
    }
}
```
+  For API details, see [CreateBucket](https://sdk.amazonaws.com/kotlin/api/latest/index.html) in *AWS SDK for Kotlin API reference*. 

### `CreateMultiRegionAccessPoint`
<a name="s3_CreateMultiRegionAccessPoint_kotlin_1_topic"></a>

The following code example shows how to use `CreateMultiRegionAccessPoint`.

**SDK for Kotlin**  
 There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/kotlin/services/s3#code-examples). 
Configure the S3 control client to send request to the us-west-2 Region.  

```
        suspend fun createS3ControlClient(): S3ControlClient {
            // Configure your S3ControlClient to send requests to US West (Oregon).
            val s3Control = S3ControlClient.fromEnvironment {
                region = "us-west-2"
            }
            return s3Control
        }
```
Create the Multi-Region Access Point.  

```
    suspend fun createMrap(
        s3Control: S3ControlClient,
        accountIdParam: String,
        bucketName1: String,
        bucketName2: String,
        mrapName: String,
    ): String {
        println("Creating MRAP ...")
        val createMrapResponse: CreateMultiRegionAccessPointResponse =
            s3Control.createMultiRegionAccessPoint {
                accountId = accountIdParam
                clientToken = UUID.randomUUID().toString()
                details {
                    name = mrapName
                    regions = listOf(
                        Region {
                            bucket = bucketName1
                        },
                        Region {
                            bucket = bucketName2
                        },
                    )
                }
            }
        val requestToken: String? = createMrapResponse.requestTokenArn

        // Use the request token to check for the status of the CreateMultiRegionAccessPoint operation.
        if (requestToken != null) {
            waitForSucceededStatus(s3Control, requestToken, accountIdParam)
            println("MRAP created")
        }

        val getMrapResponse =
            s3Control.getMultiRegionAccessPoint(
                input = GetMultiRegionAccessPointRequest {
                    accountId = accountIdParam
                    name = mrapName
                },
            )
        val mrapAlias = getMrapResponse.accessPoint?.alias
        return "arn:aws:s3::$accountIdParam:accesspoint/$mrapAlias"
    }
```
Wait for the Multi-Region Access Point to become available.  

```
        suspend fun waitForSucceededStatus(
            s3Control: S3ControlClient,
            requestToken: String,
            accountIdParam: String,
            timeBetweenChecks: Duration = 1.minutes,
        ) {
            var describeResponse: DescribeMultiRegionAccessPointOperationResponse
            describeResponse = s3Control.describeMultiRegionAccessPointOperation(
                input = DescribeMultiRegionAccessPointOperationRequest {
                    accountId = accountIdParam
                    requestTokenArn = requestToken
                },
            )

            var status: String? = describeResponse.asyncOperation?.requestStatus
            while (status != "SUCCEEDED") {
                delay(timeBetweenChecks)
                describeResponse = s3Control.describeMultiRegionAccessPointOperation(
                    input = DescribeMultiRegionAccessPointOperationRequest {
                        accountId = accountIdParam
                        requestTokenArn = requestToken
                    },
                )
                status = describeResponse.asyncOperation?.requestStatus
                println(status)
            }
        }
```
+  For more information, see [AWS SDK for Kotlin developer guide](https://docs.aws.amazon.com/sdk-for-kotlin/latest/developer-guide/use-services-s3-mrap.html). 
+  For API details, see [CreateMultiRegionAccessPoint](https://sdk.amazonaws.com/kotlin/api/latest/index.html) in *AWS SDK for Kotlin API reference*. 

### `DeleteBucketPolicy`
<a name="s3_DeleteBucketPolicy_kotlin_1_topic"></a>

The following code example shows how to use `DeleteBucketPolicy`.

**SDK for Kotlin**  
 There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/kotlin/services/s3#code-examples). 

```
suspend fun deleteS3BucketPolicy(bucketName: String?) {
    val request =
        DeleteBucketPolicyRequest {
            bucket = bucketName
        }

    S3Client.fromEnvironment { region = "us-east-1" }.use { s3 ->
        s3.deleteBucketPolicy(request)
        println("Done!")
    }
}
```
+  For API details, see [DeleteBucketPolicy](https://sdk.amazonaws.com/kotlin/api/latest/index.html) in *AWS SDK for Kotlin API reference*. 

### `DeleteObjects`
<a name="s3_DeleteObjects_kotlin_1_topic"></a>

The following code example shows how to use `DeleteObjects`.

**SDK for Kotlin**  
 There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/kotlin/services/s3#code-examples). 

```
suspend fun deleteBucketObjects(
    bucketName: String,
    objectName: String,
) {
    val objectId =
        ObjectIdentifier {
            key = objectName
        }

    val delOb =
        Delete {
            objects = listOf(objectId)
        }

    val request =
        DeleteObjectsRequest {
            bucket = bucketName
            delete = delOb
        }

    S3Client.fromEnvironment { region = "us-east-1" }.use { s3 ->
        s3.deleteObjects(request)
        println("$objectName was deleted from $bucketName")
    }
}
```
+  For API details, see [DeleteObjects](https://sdk.amazonaws.com/kotlin/api/latest/index.html) in *AWS SDK for Kotlin API reference*. 

### `GetBucketPolicy`
<a name="s3_GetBucketPolicy_kotlin_1_topic"></a>

The following code example shows how to use `GetBucketPolicy`.

**SDK for Kotlin**  
 There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/kotlin/services/s3#code-examples). 

```
suspend fun getPolicy(bucketName: String): String? {
    println("Getting policy for bucket $bucketName")

    val request =
        GetBucketPolicyRequest {
            bucket = bucketName
        }

    S3Client.fromEnvironment { region = "us-east-1" }.use { s3 ->
        val policyRes = s3.getBucketPolicy(request)
        return policyRes.policy
    }
}
```
+  For API details, see [GetBucketPolicy](https://sdk.amazonaws.com/kotlin/api/latest/index.html) in *AWS SDK for Kotlin API reference*. 

### `GetObject`
<a name="s3_GetObject_kotlin_1_topic"></a>

The following code example shows how to use `GetObject`.

**SDK for Kotlin**  
 There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/kotlin/services/s3#code-examples). 

```
suspend fun getObjectBytes(
    bucketName: String,
    keyName: String,
    path: String,
) {
    val request =
        GetObjectRequest {
            key = keyName
            bucket = bucketName
        }

    S3Client.fromEnvironment { region = "us-east-1" }.use { s3 ->
        s3.getObject(request) { resp ->
            val myFile = File(path)
            resp.body?.writeToFile(myFile)
            println("Successfully read $keyName from $bucketName")
        }
    }
}
```
+  For API details, see [GetObject](https://sdk.amazonaws.com/kotlin/api/latest/index.html) in *AWS SDK for Kotlin API reference*. 

### `GetObjectAcl`
<a name="s3_GetObjectAcl_kotlin_1_topic"></a>

The following code example shows how to use `GetObjectAcl`.

**SDK for Kotlin**  
 There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/kotlin/services/s3#code-examples). 

```
suspend fun getBucketACL(
    objectKey: String,
    bucketName: String,
) {
    val request =
        GetObjectAclRequest {
            bucket = bucketName
            key = objectKey
        }

    S3Client.fromEnvironment { region = "us-east-1" }.use { s3 ->
        val response = s3.getObjectAcl(request)
        response.grants?.forEach { grant ->
            println("Grant permission is ${grant.permission}")
        }
    }
}
```
+  For API details, see [GetObjectAcl](https://sdk.amazonaws.com/kotlin/api/latest/index.html) in *AWS SDK for Kotlin API reference*. 

### `ListObjectsV2`
<a name="s3_ListObjectsV2_kotlin_1_topic"></a>

The following code example shows how to use `ListObjectsV2`.

**SDK for Kotlin**  
 There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/kotlin/services/s3#code-examples). 

```
suspend fun listBucketObjects(bucketName: String) {
    val request =
        ListObjectsRequest {
            bucket = bucketName
        }

    S3Client.fromEnvironment { region = "us-east-1" }.use { s3 ->
        val response = s3.listObjects(request)
        response.contents?.forEach { myObject ->
            println("The name of the key is ${myObject.key}")
            println("The object is ${myObject.size?.let { calKb(it) }} KBs")
            println("The owner is ${myObject.owner}")
        }
    }
}

private fun calKb(intValue: Long): Long = intValue / 1024
```
+  For API details, see [ListObjectsV2](https://sdk.amazonaws.com/kotlin/api/latest/index.html) in *AWS SDK for Kotlin API reference*. 

### `PutBucketAcl`
<a name="s3_PutBucketAcl_kotlin_1_topic"></a>

The following code example shows how to use `PutBucketAcl`.

**SDK for Kotlin**  
 There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/kotlin/services/s3#code-examples). 

```
suspend fun setBucketAcl(
    bucketName: String,
    idVal: String,
) {
    val myGrant =
        Grantee {
            id = idVal
            type = Type.CanonicalUser
        }

    val ownerGrant =
        Grant {
            grantee = myGrant
            permission = Permission.FullControl
        }

    val grantList = mutableListOf<Grant>()
    grantList.add(ownerGrant)

    val ownerOb =
        Owner {
            id = idVal
        }

    val acl =
        AccessControlPolicy {
            owner = ownerOb
            grants = grantList
        }

    val request =
        PutBucketAclRequest {
            bucket = bucketName
            accessControlPolicy = acl
        }

    S3Client.fromEnvironment { region = "us-east-1" }.use { s3 ->
        s3.putBucketAcl(request)
        println("An ACL was successfully set on $bucketName")
    }
}
```
+  For API details, see [PutBucketAcl](https://sdk.amazonaws.com/kotlin/api/latest/index.html) in *AWS SDK for Kotlin API reference*. 

### `PutObject`
<a name="s3_PutObject_kotlin_1_topic"></a>

The following code example shows how to use `PutObject`.

**SDK for Kotlin**  
 There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/kotlin/services/s3#code-examples). 

```
suspend fun putS3Object(
    bucketName: String,
    objectKey: String,
    objectPath: String,
) {
    val metadataVal = mutableMapOf<String, String>()
    metadataVal["myVal"] = "test"

    val request =
        PutObjectRequest {
            bucket = bucketName
            key = objectKey
            metadata = metadataVal
            body = File(objectPath).asByteStream()
        }

    S3Client.fromEnvironment { region = "us-east-1" }.use { s3 ->
        val response = s3.putObject(request)
        println("Tag information is ${response.eTag}")
    }
}
```
+  For API details, see [PutObject](https://sdk.amazonaws.com/kotlin/api/latest/index.html) in *AWS SDK for Kotlin API reference*. 

## Scenarios
<a name="scenarios"></a>

### Create a presigned URL
<a name="s3_Scenario_PresignedUrl_kotlin_1_topic"></a>

The following code example shows how to create a presigned URL for Amazon S3 and upload an object.

**SDK for Kotlin**  
 There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/kotlin/services/s3#code-examples). 
Create a `GetObject` presigned request and use the URL to download an object.  

```
suspend fun getObjectPresigned(
    s3: S3Client,
    bucketName: String,
    keyName: String,
): String {
    // Create a GetObjectRequest.
    val unsignedRequest =
        GetObjectRequest {
            bucket = bucketName
            key = keyName
        }

    // Presign the GetObject request.
    val presignedRequest = s3.presignGetObject(unsignedRequest, 24.hours)

    // Use the URL from the presigned HttpRequest in a subsequent HTTP GET request to retrieve the object.
    val objectContents = URL(presignedRequest.url.toString()).readText()

    return objectContents
}
```
Create a `GetObject` presigned request with advanced options.  

```
suspend fun getObjectPresignedMoreOptions(
    s3: S3Client,
    bucketName: String,
    keyName: String,
): HttpRequest {
    // Create a GetObjectRequest.
    val unsignedRequest =
        GetObjectRequest {
            bucket = bucketName
            key = keyName
        }

    // Presign the GetObject request.
    val presignedRequest =
        s3.presignGetObject(unsignedRequest, signer = CrtAwsSigner) {
            signingDate = Instant.now() + 12.hours // Presigned request can be used 12 hours from now.
            algorithm = AwsSigningAlgorithm.SIGV4_ASYMMETRIC
            signatureType = AwsSignatureType.HTTP_REQUEST_VIA_QUERY_PARAMS
            expiresAfter = 8.hours // Presigned request expires 8 hours later.
        }
    return presignedRequest
}
```
Create a `PutObject` presigned request and use it to upload an object.  

```
suspend fun putObjectPresigned(
    s3: S3Client,
    bucketName: String,
    keyName: String,
    content: String,
) {
    // Create a PutObjectRequest.
    val unsignedRequest =
        PutObjectRequest {
            bucket = bucketName
            key = keyName
        }

    // Presign the request.
    val presignedRequest = s3.presignPutObject(unsignedRequest, 24.hours)

    // Use the URL and any headers from the presigned HttpRequest in a subsequent HTTP PUT request to retrieve the object.
    // Create a PUT request using the OKHttpClient API.
    val putRequest =
        Request
            .Builder()
            .url(presignedRequest.url.toString())
            .apply {
                presignedRequest.headers.forEach { key, values ->
                    header(key, values.joinToString(", "))
                }
            }.put(content.toRequestBody())
            .build()

    val response = OkHttpClient().newCall(putRequest).execute()
    assert(response.isSuccessful)
}
```
+  For more information, see [AWS SDK for Kotlin developer guide](https://docs.aws.amazon.com/sdk-for-kotlin/latest/developer-guide/presign-requests.html). 

### Create a serverless application to manage photos
<a name="cross_PAM_kotlin_1_topic"></a>

The following code example shows how to create a serverless application that lets users manage photos using labels.

**SDK for Kotlin**  
 Shows how to develop a photo asset management application that detects labels in images using Amazon Rekognition and stores them for later retrieval.   
For complete source code and instructions on how to set up and run, see the full example on [ GitHub](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/kotlin/usecases/creating_pam).  
For a deep dive into the origin of this example see the post on [AWS Community](https://community.aws/posts/cloud-journeys/01-serverless-image-recognition-app).  

**Services used in this example**
+ API Gateway
+ DynamoDB
+ Lambda
+ Amazon Rekognition
+ Amazon S3
+ Amazon SNS

### Detect objects in images
<a name="cross_RekognitionPhotoAnalyzer_kotlin_1_topic"></a>

The following code example shows how to build an app that uses Amazon Rekognition to detect objects by category in images.

**SDK for Kotlin**  
 Shows how to use Amazon Rekognition Kotlin API to create an app that uses Amazon Rekognition to identify objects by category in images located in an Amazon Simple Storage Service (Amazon S3) bucket. The app sends the admin an email notification with the results using Amazon Simple Email Service (Amazon SES).   
 For complete source code and instructions on how to set up and run, see the full example on [GitHub](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/kotlin/usecases/creating_photo_analyzer_app).   

**Services used in this example**
+ Amazon Rekognition
+ Amazon S3
+ Amazon SES

### Get an object from a Multi-Region Access Point
<a name="s3_GetObject_MRAP_kotlin_1_topic"></a>

The following code example shows how to get an object from a Multi-Region Access Point.

**SDK for Kotlin**  
 There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/kotlin/services/s3#code-examples). 
Configure the S3 client to use the Asymmetric Sigv4 (Sigv4a) signing algorithm.  

```
        suspend fun createS3Client(): S3Client {
            // Configure your S3Client to use the Asymmetric SigV4 (SigV4a) signing algorithm.
            val sigV4aScheme = SigV4AsymmetricAuthScheme(DefaultAwsSigner)
            val s3 = S3Client.fromEnvironment {
                authSchemes = listOf(sigV4aScheme)
            }
            return s3
        }
```
Use the Multi-Region Access Point ARN instead of a bucket name to retrieve the object.  

```
    suspend fun getObjectFromMrap(
        s3: S3Client,
        mrapArn: String,
        keyName: String,
    ): String? {
        val request = GetObjectRequest {
            bucket = mrapArn // Use the ARN instead of the bucket name for object operations.
            key = keyName
        }

        var stringObj: String? = null
        s3.getObject(request) { resp ->
            stringObj = resp.body?.decodeToString()
            if (stringObj != null) {
                println("Successfully read $keyName from $mrapArn")
            }
        }
        return stringObj
    }
```
+  For more information, see [AWS SDK for Kotlin developer guide](https://docs.aws.amazon.com/sdk-for-kotlin/latest/developer-guide/use-services-s3-mrap.html). 
+  For API details, see [GetObject](https://sdk.amazonaws.com/kotlin/api/latest/index.html) in *AWS SDK for Kotlin API reference*.