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RE: 20060330: dynamic website with Gempak

Hello Steve,

These examples are really good and will help a lot. Yes, <OBJECT> tag
was something I was thinking about too. The snippets make the idea very
clear. I will keep you updated on how things work out at my end.

Steve, thank a lot for your help, as always.

Sincerely,
Chirag Shukla
South Dakota State University






-----Original Message-----
From: Steve Chiswell [mailto:address@hidden] 
Sent: Thursday, March 30, 2006 12:02 PM
To: Shukla, Chirag
Cc: address@hidden
Subject: 20060330: dynamic website with Gempak

Chirag,

Now that I'm in my office....

Attached is the source for a program I call showwebgif.
It will read the file from disk, stream the output and then delete the
file from disk. Below is an example of the usage:
www.unidata.ucar.edu/cgi-bin/rtstats/rtstats_topogif?CONDUIT

The script itself runs a gpmap using the GIF device (in this case
gpmap_gif, though you don't have to use the _gf or _gif versions, it
ensures that you don't have hung "gplt" problems in the long run), and
upon completion of the gif generation in a $WORK working directory (eg
/tmp/latmap.$$) and does the following:

######### SNIP ######################
if(-e gempaktopo.gif) then
   $CGIDIR/showwebgif gempaktopo.gif
else
        echo 'Content-type: text/html'
        echo ''
        echo "<html>"
        echo "<Head><Title>TOPOMAP</Title></Head>"
        echo "<Body><H1>Post Results</H1>"
        echo "<pre>"
        cat latmap.log
        echo "</pre>"
        echo "</body>"
        echo "</html>" 
endif

cd /tmp
rm -rf $WORK
############# END SNIP ###############

When sucessful, the showwebgif program will remove the gif file.
If the gpmap program fails to create the gif, an html page is created.
The script then rmoves its working directory and the gempak .nts files
that were created.


You can actually imbed a gif within a web table such as I do here:
http://www/cgi-bin/rtstats/rtstats_sitebyfeed?CONDUIT
By using the <OBJECT> tag (older web browsers may not follow that tag
however). The <td> table cell generation of the script looks like:

echo '<td width="450" style="vertical-align: top">'
echo '<P>'
echo '<A
HREF="http://www.unidata.ucar.edu/cgi-bin/rtstats/rtstats_topogif?'${FEE
D}'">'
echo '<OBJECT
data="http://www.unidata.ucar.edu/cgi-bin/rtstats/rtstats_topogif?'${FEE
D}'"
 type="image/gif" width="450px">'
echo 'Topology map'
echo '</OBJECT>'
echo '</a>'
echo '</td>'

The object tag tells the browser to obtain the data from the URL without
the user having to click on the link.

Let me know if you have other questions regarding use of GEMPAK!


Steve Chiswell
Unidata User Support


On Thu, 2006-03-30 at 07:41, Shukla, Chirag wrote:
> Hi Steve,
> 
> This certainly sounds very promising and I like the idea of using MIME

> types. I will give it a try and will let you know how if something 
> goes wrong.
> 
> Thanks for the tips :)
> 
> Sincerely,
> Chirag Shukla
> South Dakota State University
> 
> 
> -----Original Message-----
> From: Steve Chiswell [mailto:address@hidden]
> Sent: Thursday, March 30, 2006 8:00 AM
> To: Shukla, Chirag
> Cc: address@hidden
> Subject: Re: dynamic website with Gempak
> 
> Chirag,
> 
> I do many images from cgi.
> In regard to images, if you expect a large number of requests for 
> non-similar images , then you can create them dynamically and then 
> instead of putting on your web site for viewing with the normal <IMG 
> SRC=""> command, where you will have to maintain the image for some 
> period of time- you can send them within the page using a mime type of

> image/gif and immediately delete the file.
> 
> I have a short program for putting the mime block in a web page but it

> is easy to do in perl or php as well. The advantage here I see is that

> you won't risk filling up disk space if your image creation gets 
> unexpectedly punded on, and, you don't have to have a directory on 
> your web server writable by the web server (web, nobody) process since

> the dynamic page is built and streamed without storing on disk.
> 
> Some examples here are the rtstats web pages under:
> www.unidata.ucar.edu/sortare/idd/rtstats
> and radar images under
> motherlode.ucar.edu/unidata/images/nids/gdradr.html
> 
> If needed, I can put together some web examples for these scripts,
> 
> Steve Chiswell
> Unidata User Support
> 
> On Wed, 29 Mar 2006, Shukla, Chirag wrote:
> 
> > Hi Steve,
> >
> > Hope you are doing excellent.
> >
> > I was thinking of using Gempak as a tool for dynamic 
> > interaction/visualization on websites. Here is what I was thinking:
> > A user submits a form after choosing a date, server side script 
> > grabs data from a database to create a text file followed by calling

> > a .csh file. The .csh file creates a .gem file and invokes sfmap to 
> > create a temporary image. This image is rendered back to the 
> > webpage. Error checks can be placed in the server side script. 
> > Temporary images can be flushed off every few hours.
> >
> > Someone might have tried this already. Do you think this is a 
> > practical approach?
> >
> > Thanks. Have a great time.
> >
> > Sincerely,
> > Chirag Shukla
> > South Dakota State University
> >