Does Cache really cause some problem in reality?
Hello! Everyone! I am a website tester. During testing website, Cache issue often bothers my test result. For example, it may give me a wrong price for a certain product in a shopping cart. Then I have to clear the cache first in order to get expected result.
So I am wondering if a real user may get a wrong price in a shopping cart in reality because of cache.
Thanks in advance!
from the consumer's point of view, the cache isn't as much of a problem since expiration is usually a time period that's much less than the release cycle (like 1 day, where a release cycle is ususally a few weeks to a few months apart.). As for QA, since we're hitting the same site multiple times in a single day, we have to start our tests with a clean slate each time. Programs like CCleaner makes it easier.
However, it is important to test the caching as well.
Are the expiration periods set right? say if an expiration period is set too long, the customer will never see an updated version of your site like the scenario you outlined above.
On the privacy front, say if a cache header is set for time sensitive data, which you want to have expire upon first view. This is because caching not only happens on the customer's computer, it can also happen on the ISP level too, for them to reduce overall bandwidth usage for commonly visited pages. You do not want a user's sensitive information to get into the next visitor's hands.
On the security front. There's a common web attack called http cache poisoning. This allows the attacker to write their content into an ISP's cache if your web app does not properly sanitize it's header information.