Last year, as part of the Version 2 release of the AWS Mobile SDK for Android, we introduced the ability to pause and resume transfers. Since then, we have received helpful feedback from the community, and learned more about the needs of mobile developers like you. Today we are pleased to announce the introduction of a new and easier way to transfer data between your Android app and Amazon S3, the S3 Transfer Utility for the AWS SDK for Android.

What is difference between the Transfer Utility and the Transfer Manager?

The Transfer Utility is a new client, with many of the same features as the Transfer Manager, but designed to be simpler and more efficient to use.

Some of the feature enhancements include:

• It uses the local SQLite database to persist all metadata about transfers, allowing them to be paused and resumed without the developer having to serialize or persist any data.
• It utilizes native Android Services so you don’t have to worry about threading or the app being killed.
• It automatically pauses and resumes transfers when internet connectivity is lost and regained.
• It has general configuration improvements for performance with S3 on mobile.

The detailed differences are described in the sections below.

Uploading and Downloading

The Transfer Manager has APIs that support the use of I/O streams. With these APIs, pausing and resuming was not possible. Additionally, you had to specify the content size ahead of time, further reducing the usefulness of streams. With the Transfer Utility there is one file based API for uploading and downloading, which you can always pause or resume (on top of the automatic pause and resume functionality described below).

The Transfer Utility makes tracking transfers more mobile friendly. The primary way of tracking transfers is through instances of the TransferObserver class. TransferObserver instances are returned from the download() and upload() methods. They are automatically saved to local storage and can be queried for based on id, type (upload, download, or any), or state (such as paused) from anywhere within the app as shown below.