Browser requests for images

Question

I've been doing some experimenting with php and html, and I'd like to know if it's possible for the browser to send a separate request for multiple images that have the same file name. For example, if I had

<img src="showimg.php?id=1234"> 

written out 3 different times, is it possible for the browser to send the request 3 different times, thus getting a different image each time? It seems so far that the browser recognizes that the file name is the same and then just serves up the image from the cache. I came to this conclusion by using a session variable that increments every time showimg.php is accessed. If the id is different then the counter gets incremented 3 times. But if all three id's are the same then the counter only gets incremented once no matter how many times I request the image. Since I am no authority on browsers, I was hoping someone could provide a concrete answer.

EDIT: My question is: How can I force the browser to load a different image using the same id. I know it can be done with unique ids. I'm just wondering if this is possible.

Thank you to those who have responded so far, though.

Answer 1

You can disable caching for showimg.php by specifying Cache-Control header in showimg.php:

<?php header("Cache-Control: no-cache"); ?>

Also you can add second attribute to showimg.php which can be ignored by script, but browser will treat it as different file.

And yes, incrementation can be managed via sessions or cookies.

Answer 2

I think the only choice you have is to append some random string to the image to make the "file name" unique. Otherwise the browser will (rightly) assume that files with the same URL are the same image. From a REST point of view, they should be.

<img src="showimg.php?id=1234&rand=<?php echo uniqid(); ?>">