voplot issues

[Gerard Lemson]

To whom it may concern

I have been using VOPlot succesfully in a few use cases, which revealed
some issues about which I want to ask some questions and give some comments.

1.
I have made the VOPlot applet available in web applications that allow
querying of a relational database online.
The user can select to have the result set plotted in a VOPlot applet.
See http://www.g-vo.org/mpasims/QueryManager? for an example.
This is excellent for quick evaluation of the result set online and is great
for
demonstrations. However, referring to a recent email from Alex Szalay on the
IVOA
on the ivoa mailing list, about the VOPlot licensing,

"
To me 3a means that a system manager cannot install this on
a server -- rather every user has to download and install
directly from India.

I did not read this until now, but this will make it difficult
to incorporate and use VOPlot broadly, like making it part of
an archive interface external to VO India -- if this licence
really means what it says.
"

I am no expert in reading license documents, so please can you let me know
whether my use of the applet this way is legal ?

2.
I noticed that a potentially very useful feature is absent in version
1.2 of VOPlot, as well as in the 1.2.1 source version.
This feature is that, when one selects a subset of points in the plot,
showing say column A vs column B, the same points will still be highlighted
when I switch to viewing say column C against column D.
In the latest version of VOPlot the points are deselected.
I have investigated the source code version (thanks very much for providing
this btw !)
and found that a simple code change in the drawPlot(boolean, boolean) method
in
com.jvbt.applets.PlotVOApplet seems to correct this.
I have tested this out on users of private versions of the web based
querying tool and they are enthousiastic about this feature. It is an
example
of a feature that is very hard to emulate for example in IDL.

I understand there may be issues with such code changes and making them
available
to other users. What are these ? Could you create a version of the tool that
(again ?) incorporates this feature ?

I will send you my updated version of this applet in a separate email.

3.
Finally a question following up on the previous comment.
Is it already possible, or would it be possible to add the capability
to a future version, to use a set of selected points to define a filter?

Thanks

Gerard Lemson


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* Gerard Lemson                       * Tel: +49 (0)89 30000-3316
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