https://bz.apache.org/bugzilla/show_bug.cgi?id=63100
Bug ID: 63100
Summary: Streaming data for browsers
Product: POI
Version: 3.17-FINAL
Hardware: PC
OS: Mac OS X 10.1
Status: NEW
Severity: normal
Priority: P2
Component: SXSSF
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
SXSSF works as designed and manages a small memory footprint when generating
large files from a database. But it only writes data to an output stream once
everything has been written to SXSSF. This is problematic when used in web
applications:
In our use case (our website allows users to generate Excel from the database),
generating the SXSSF on the server takes about 5 minutes. Most clients give up
within a minute (or the browser does it automatically), or the proxy times out
due to no data being sent. Some users also retry the download request. A new
request for download is initiated (while the server is busy generating the
SXSSF for a client that already gave up). This can potentially lead to DOS.
To work around this issue, I've implemented a super-streaming version of SXSSF,
a `SuperSXSSF`, that relies on `rowWriter` callback to generate row data.
With this approach our service is able to stream the generated Excel directly
to the client and, best of all, is terminated in case the user cancels the
download request.
The `SuperSXSSF` prevents both download timeouts and potential DOS, while
allowing developers all other XSSF actions (i.e. define styles) that don't take
much processing time.
Now what?
Modifications at:
https://gitlab.croptrust.org/genesys-pgr/genesys-server/tree/master/src/main/java/org/apache/poi/xssf/streaming
Use case:
https://gitlab.croptrust.org/genesys-pgr/genesys-server/blob/master/src/main/java/org/genesys2/server/service/impl/DownloadServiceImpl.java
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