[mapserver-users] Mapscript/Java/Servlet users: give this a whirl...

[Dan Barron]

CF,

I have wanted to use Java Mapscript with my servlet but I can't seem to get 
it to compile under W2K. After reading this thread I think I will wait 
until Java Mapscript is farther along.  For now I am creating a dynamic map 
on the fly by using PHP/Mapscript.  My servlet gathers/creates the 
appropriate url parameters which are then passed to PHP script via 
JSP.  PHP then passes the appropriate request parameters w/ generated 
images back to the servlet.  It feels like a hack, and a round about way to 
get a dynamic map, but it works and does not crash.  There is a performance 
hit though, and it is not the speedy answer.  For me this was the easiest 
path to dynamic maps.  I use JBoss w/ Tomcat on W2K, with Apache and PHP 
module.  You can see a development site at www.ddive.com - go through the 
demo account and click the first map icon you see to get an example and see 
the peformance.

Dan Barron
Destination Software LLC

At 11:25 AM 6/27/2002 -0600, you wrote:
>Thanks for you sharing your experience.  That really helps... even if it 
>wasn't what I wanted to hear :)
>In fact, on my way in to work this morning (where I have plenty of time to 
>sit in my car and ponder such things).... I began going over all my 
>requirements again and wondering if I may be able to get around the whole 
>problem by doing something similar to what you said.... just using JSP (or 
>whatever) to manipulate the submitted URL parameters (and possibly 
>creating a mapfile on the fly) and forwarding the request to the CGI 
>program.  That just might be good enough for me.
>Just out of curiousity though, I think I will try your thread locking 
>solution below.  I agree with you about "scalability".  That is not my 
>primary concern right now.  If I ever get that many users, I'll find a way 
>to deal with it.  My main concern is stability, speed and 
>functionality.  It seems that mapserv is pretty bulletproof, so maybe this 
>jsp->cgi option is the best if I'm able to accomplish everything I need.
>
>
>>From: David Graham <dgraham at i3.com>
>>To: C F <gis_consultant at hotmail.com>
>>CC: hwehr at hs-harz.de,  mapserver-users at lists.gis.umn.edu
>>Subject: Re: [mapserver-users] Mapscript/Java/Servlet users: give this a 
>>whirl...
>>Date: Thu, 27 Jun 2002 10:52:45 -0600
>>
>>CF,
>>
>>It is a threading issue. I was woring with java and mapserver back last 
>>fall with pre-release 3.5. I know they have been working on the thread 
>>safe issues in mapserver but it does not supprise me that it has not 
>>gotten there yet. I have sepent a good bit of time inside the mapserver 
>>(maplib) code and have found numerous items that sent up red flags for 
>>thread safe utilization. In the end I deciced not to connect mapserver 
>>directly to tomcat but to simply call the mapserv CGI from tomcat. This 
>>was suitable for us since we did not need dynamic content on the map 
>>part. It may not work for you.
>>
>>One thing you might want to do is to mashal threads prior to calling the 
>>offending subroutine. You would do it by sinchronizing on a singular 
>>object in the JVM. Yes this will cause a bottle neck and a lack of 
>>scalablility. But you should ask yourself what is your current user base 
>>before you worry too much about scalablility. (My experience shows that 
>>scalablility is over rated. Most businesses I have worked for that 
>>worried too much about scalablility up front, have found themselfs 
>>decaring bankrupsy because traffic never did ramp up! Is your product 
>>really going to be in that much demand?)
>>
>>Here is how you would do it.
>>
>>public static class MyLock {
>>// This class does nothing is just used to lock threads against.
>>}
>>
>>inside your subroutine
>>code....
>>synchronize ( MyLock ) {
>>offending_subroutine( args );
>>}
>>more code...
>>
>>Dave Graham
>
>
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