ChartDeleter.java doesnt implement Serializable Interface

[sumanseshadri]

Hi All,
Currently, I am using jfreechart-1.0.1.jar and tomcat 5.5.9. But when I upgraded to tomcat 5.5.20, tomcat throws the following error:

java.lang.IllegalArgumentException: setAttribute: Non-serializable attribute

at org.apache.catalina.session.StandardSession.setAttribute(StandardSession.java:1255)

at org.apache.catalina.session.StandardSession.setAttribute(StandardSession.java:1233)

at org.apache.catalina.session.StandardSessionFacade.setAttribute(StandardSessionFacade.java:129)

at org.jfree.chart.servlet.ServletUtilities.registerChartForDeletion(ServletUtilities.java:313)

at org.jfree.chart.servlet.ServletUtilities.saveChartAsPNG(ServletUtilities.java:192)


In version 1.2 of ChartDeleter.java (which is the released part of the jfreechart.jar - 1.0.3) it doesn't implement java.io.Serializable . However,
in 1.2.2.2 which is the second version on the "STABLE_1-0-0" branch it does implement Serializable.

http://jfreechart.cvs.sourceforge.net/j ... a?view=log

So, I would like to know whether a State version (1.0.4) could be available with ChartDeleter.java implementing the Serializable interface. And if yes, it would be nice to know the estimated date.

The only work around now, is to change the following line FROM:

String filename= ServletUtilities.saveChartAsPNG(chart, imageWidth, imageHeight, info, session);

TO:

String filename= ServletUtilities.saveChartAsPNG(chart, imageWidth, imageHeight, info, null);


I think this will result in the chart not being in session and the chart will be generated from scratch everytime, which will slow the performance.

Any information on this is appreciated.

Thank you,
Suman

[angel]

I think this will result in the chart not being in session and the chart will be generated from scratch everytime, which will slow the performance.

I will only slow the performance, when you want reuse the chart. But in most cases the image is intended to be actual, so this behavior is disired anyway.

[david.gilbert]

ChartDeleter has been made Serializable in CVS, but I'm not sure if that is correct. The purpose of this class is to delete a file (chart image) from the local file system when the user's session expires...it isn't clear to me that this will work in a clustered server environment. In fact, it seems to me that it won't work...but I don't do any server side development work, so perhaps someone else can comment.

[Taqua]

Hi,

most application server bind a session in a clustered environment to a specific host. But who ever is using the ChartDeleter (or temporary files) in a clustered environment has no clue about safe and sane programming and deserves all the trouble he gets

The fix itself makes sure that Tomcat and all other servlet container that try to persist sessions to the disk or database can work with that file.

Btw.: The Servlet spec state that each attribute that is added to a SessionContext *has* to be Serializable. If it's not, it's a violation of the standard.

Regards,
Thomas

[david.gilbert]

Hi Thomas,

Thanks for the follow-up. Given what you've said, I'm happy to leave the Serializable fix in there for the 1.0.4 release (which ought to be out some time this week).

[sumanseshadri]

Thank you all very much for your prompt response. I will check out the 1.0.4 release.

-Suman