Update picture in browser

[Fawcett, David]

If you give the image a unique name each time that you draw it, browser
caching shouldn't be an issue.  

-----Original Message-----
From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
Behalf Of Simon
Sent: Wednesday, November 07, 2007 5:25 AM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: [UMN_MAPSERVER-USERS] Update picture in browser


Hi, 

im sorry for this stupid question, but I'm running out of ideas.

I created a jsp Page using mapscript to generate a gif picture out of my
GIS Data, and it works just fine.

The jsp page receives the GIS Data via a webservice ... so the Data
changes and the picture is newly-created each time the GIS Data has
changed.

The problem is, that my browser ignores the changes sometimes. So, the
page is loaded again and the shown picture is still the old one, even
though it doesn't exist anymore.

The picture is shown in an <input> tag, here is the code:

page.jsp
========

<meta http-equiv="expires" content="0">
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">

...

<%
mapObj map = new mapObj(mapfile); //mapfile is resolved out of a POST
request
imageObj image = map.draw();  	  	
image.save(this.tmpPath+"/picture.gif",map);

%>

out.println("<div id=\"map\" >");
out.println("<input type=\"image\" name=\"karte\"
src=\""+picturePath+"?id="+Math.round(Math.random()*100000)+"\" >" );
out.println("</div>");			

where picturePath is the URL to the created picture.
The part with the random number is a solution for this problem from a
php forum, but it doesn't work so far.

My first idea was, that there is a problem with my IE cache. So I added
meta tags to my jsp page ... but the problem seems to be somewhere else.

A possible solution would be to give the picture an ID which changes
every time the picture is created ... but this would be a bit sloppy I
think.

Well, maybe somebody of you had simliar experiences ... hopefully.

thanks in advance.

Simon