Primefaces fileUpload and session timout

Question

Could a session timeout happen if there are several very big files are uploaded? Imagine I upload one 5 GByte big file and a short session timeout is set. Could the session timeout occur during streaming the file?

Answer 1

Yes, it can. The servlet specification does nowhere forbid that a session could be destroyed during an active request. You'll thus risk a ViewExpiredException when such an upload arrives at bean.

If this is your concern, you've several options:

1. Let the upload form asynchronously poll to the server at intervals to keep the session alive. You can in EL use #{session.maxInactiveInterval} to obtain the current timeout in seconds.

   <p:fileUpload ... />
   <p:poll interval="#{session.maxInactiveInterval - 10}" async="true" />
   

   The 10 seconds difference is just to prevent that it arrives a few seconds too late because the page itself may also take some time to load all the HTML and to initialize the poll. You can if necessary conditionally start/render the poll on start of upload.

   ---

2. Let the "onstart" event of upload increase the session timeout to a certain limit (hour?) and let the "oncomplete" event of upload put it back.

   <p:fileUpload ... onstart="increaseTimeout()" oncomplete="resetTimeout()" />
   <p:remoteCommand name="increaseTimeout" listener="#{bean.increaseTimeout}" />
   <p:remoteCommand name="resetTimeout" listener="#{bean.resetTimeout}" />
   

   You can in bean use ExternalContext#setSessionMaxInactiveInterval() to set the desired session timeout in seconds.

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3. Use a stateless JSF form. The view will never expire, regardless of how the HTTP session behaves.

   <f:view transient="true">
       ...
   </f:view>
   

   Note: any view scoped beans tied to such a view will behave like request scoped ones. To avoid confusion, replace the annotations if necessary.