Problem with browser caching

[Pranav Bhatt]

Hi,
I'am working on a pagination problem. I am posting data from my Action class to the display JSP and when user press Next link again flow goes to Action class then to same JSP again with new data.

i have used the rownum query in action and it keeps changing the lower_bound and upper_bound with every call to execute() in my action as below-:

  
SELECT * FROM (SELECT a.*, ROWNUM rnum FROM "
				+ "(SELECT * FROM codes)"
				+ " a WHERE ROWNUM <=" + upper_bound + ") WHERE rnum >="
				+ lower_bound;  

with each call from my jsp with Next link

<a href='query.do?page=<%=a%>'>Next</a>

.

All is working fine but am getting the rows appended with previous rows in my JSP. That is for first request am getting 15 rows. Again a click on Next is giving me 30 rows with 15 new rows appended to previous 15. I tried to clear browser cache as below but it doesn't seem to work-:

   <%
	response.setHeader("Cache-Control", "no-store"); //HTTP 1.1 
	response.setHeader("Pragma", "no-cache"); //HTTP 1.0 
	response.setDateHeader("Expires", 0); //prevents caching at the proxy server
%> 

My URL is not same for every query as my page parameter value is getting changed every time still its not working as expected.

I had put a output statement on Action class, just to be sure am getting result in incremental sets. It seems fine from below result of two consecutive calls-:

  
Query is-:SELECT * FROM (SELECT a.*, ROWNUM rnum FROM (SELECT * FROM user_codes) a WHERE ROWNUM <=15) WHERE rnum >=1

Query is-:SELECT * FROM (SELECT a.*, ROWNUM rnum FROM (SELECT * FROM user_codes) a WHERE ROWNUM <=30) WHERE rnum >=16 
 

Please inform i did not make my point clear. i tried this in Mozilla, IE , both gives same result.

Anyone having any idea how to get around this...

[Pranav Bhatt]

Thanks i have solved it.. Its working now..

[Ankit Garg]

Its good to know that its working. Well these are the response headers that I use to prevent caching

response.setDateHeader("Expires", 0);
response.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");
response.addHeader("Cache-Control", "post-check=0, pre-check=0");
response.setHeader("Pragma", "no-cache");

[Bauke Scholtz]

All other cache-control fields are pointless when no-cache is specified.

[Mark Williams]

My question probably depends on the client but, what effect do these no cache headers have on images referenced in the HTML? It should be none right? I am thinking that the no cache header only applies to the HTML and not the objects that the HTML tells the browser to request.

[Bauke Scholtz]

Images are obtained by fully separate and independent requests fired by the webbrowser itself after examing the 'src' attribute.

[Mark Williams]

Bauke Scholtz wrote:Images are obtained by fully separate and independent requests fired by the webbrowser itself after examing the 'src' attribute.

So, I will assume that the headers are not stopping the browser from caching images on the page. Thanks.

[Bauke Scholtz]

Indeed. The response headers only applies on the current request/response and certainly not on others.