title: S3 upload and access-How to monitor the direct upload of files from client to s3 from server?
body: <p>I am new to AWS.
  I am learning upload a file from client directly to s3.Here are the steps</p>
  <ol>
  <li>Client-1 sends request for file upload.</li>
  <li>Server generates pre-signed url,keys etc and sends it to client-1.</li>
  <li>Client-1 uploads the files directly to s3 using the keys it received from server.</li>
  </ol>
  <ul>
  <li>Now how can server (application) know that upload was successful?</li>
  <li>How can server access s3 content (Just like it accesses database content-like how many files are there,etc)?</li>
  <li>If client-2 wants to access a file uploaded by client-1,how server can
  programmatically give access to client-2 ? (Like expiring
  tokens,signed URLs.. Like how Facebook uses a long url with access keys for images,etc)</li>
  </ul>
  <p>Thank you for answering!</p>