I have a chart control that I developed. It creates the chart based on each person login info, save it to the disk, and sends an image tag in its render method back to the main page:
something like <image src="newimageid.gif" > ..

The problem is, sometimes, the pages get rendered, there is image placeholder in the rendered page, but the image does not show. Sometimes, it show, sometimes it does not. If i hit refresh, it shows up. somtimes ihave to hit refresh 2/3 times before it finally shows up.

can someone please shed somelight on it as to what might be going on ?

One possible solution I am looking at is, if somehow i can stream the image back to the main page. I have been able to do that when the final page has nothing else but the image, but when it has other stuff also (like proper html tags etc), the image comes as garbage data.

can anyone please give me some idea regarding this? how an image can be sent back to the page instead of being saved on the hard disk when the main page has other data also? or give me some idea why images do not show up unless you hit refresh? and what could be a possible solution to that?

Thanks
Ali

The problem is, sometimes, the pages get rendered, there is image placeholder in the rendered page, but the image does not show. Sometimes, it show, sometimes it does not. If i hit refresh, it shows up. somtimes ihave to hit refresh 2/3 times before it finally shows up.

Have you checked if image is created when above described problem occurs? does your control render correct tag?

This are few ways you can render dynamic images.


1) control or page creates image on harddrive and renders Image html tag on browser. (probably you are doing this way)

2) Render tag like <img src="dynamicimage.aspx?PARAM1=VA1&PARAM2=VAL2......" /> Where dynamicimage.aspx is page which streams image according to passed params.

3) Control or page generates images in memory and save to session or cache(with any uniqueid) and renders image tag like <img src="imageserver.aspx?id=uniqueid" /> and imageserver.aspx uses unique id to retrive image from memory or cache and streams.

Every method has its own pros and cons, select which best suits to your application.

I have the same problem. Most the pictures render nicely, but often a few (10%) show up as a red x.

I use the method you describe as 3)

I tried several different settings concerning cache, with no luck.

It happens both on my development pc, and on the production server.

Any ideas would be appreciated.