# Controlling iostreams used by the `HttpClient` and the `AWSClient` in the AWS SDK for C\$1\$1
<a name="configuring-iostreams"></a>

By default, all responses use an input stream backed by a `stringbuf`. If needed, you can override the default behavior. For example, if you are using an Amazon S3 `GetObject` and don’t want to load the entire file into memory, you can use `IOStreamFactory` in `AmazonWebServiceRequest` to pass a lambda to create a file stream.

 **Example file stream request** 

```
 //! Use a custom response stream when downloading an object from an Amazon Simple
//! Storage Service (Amazon S3) bucket.
/*!
  \param bucketName: The Amazon S3 bucket name.
  \param objectKey: The object key.
  \param filePath: File path for custom response stream.
  \param clientConfiguration: AWS client configuration.
  \return bool: Function succeeded.
 */

bool AwsDoc::SdkCustomization::customResponseStream(const Aws::String &bucketName,
                                                    const Aws::String &objectKey,
                                                    const Aws::String &filePath,
                                                    const Aws::Client::ClientConfiguration &clientConfiguration) {

    Aws::S3::S3Client s3_client(clientConfiguration);

    Aws::S3::Model::GetObjectRequest getObjectRequest;
    getObjectRequest.WithBucket(bucketName).WithKey(objectKey);

    getObjectRequest.SetResponseStreamFactory([filePath]() {
            return Aws::New<Aws::FStream>(
                    "FStreamAllocationTag", filePath, std::ios_base::out);
    });

    Aws::S3::Model::GetObjectOutcome getObjectOutcome = s3_client.GetObject(
            getObjectRequest);

    if (getObjectOutcome.IsSuccess()) {
        std::cout << "Successfully retrieved object to file " << filePath << std::endl;
    }
    else {
        std::cerr << "Error getting object. "
                  << getObjectOutcome.GetError().GetMessage() << std::endl;
    }

    return getObjectOutcome.IsSuccess();
}
```

**Note**  
 There's more on GitHub. Find the complete example in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/cpp/example_code/sdk-customization#code-examples).