S3 Presigned Url Callback
<p>Is there a way to know if someone has uploaded something to generated public presigned url of S3? Like a callback that will trigger my servlet.</p>

<p>For example:</p>

<p>I created a presigned url from this <a href="http://docs.aws.amazon.com/AmazonS3/latest/dev/ShareObjectPreSignedURLJavaSDK.html" rel="nofollow">docs</a></p>

<pre><code>AmazonS3 s3Client = new AmazonS3Client(new ProfileCredentialsProvider()); 

java.util.Date expiration = new java.util.Date();
long msec = expiration.getTime();
msec += 1000 * 60 * 60; // Add 1 hour.
expiration.setTime(msec);

GeneratePresignedUrlRequest generatePresignedUrlRequest = new GeneratePresignedUrlRequest(bucketName, objectKey);
generatePresignedUrlRequest.setMethod(HttpMethod.PUT); 
generatePresignedUrlRequest.setExpiration(expiration);

URL url = s3client.generatePresignedUrl(generatePresignedUrlRequest); 

// Use the pre-signed URL to upload an object.
</code></pre>

<p>then, I give the <code>url</code> to someone and if that someone upload something to that <code>url</code>, the <code>http://example.com/upload</code> will be invoked with data from uploaded file.</p>