0:00 Whats an eTag? 4:30 Pros of eTags 7:10 Cons of eTags 12:35 Hulu use of eTags as zombie cookies

love your series man ! it is very real based problems which we face in real software develpment ! keep up good work

Question of the day have you ever used eTags? If not now that you know about them would you consider using them and why?

Thank you! Exactly the explanations I was looking for!

Where does cached data return from ? In Nodejs with Express lets assume etag is enabled Then from where the cached response being used , is it stored at client side or server side in memory ?

@Hussein Nasser , I haven't used etags before. I am considering using it in a use case with the following details. I have a json file stored in a storage account of the cloud provider, it is the responsibility of some micro service in our k8s cluster to read and serve this json (sometime after filtering) to another type of MS in our cluster. All the replicas of the ms read the same file(something known as PVC or persistent storage claim). This enables me to read the file once, store it in memory and in all the following calls to only read the file last modification from metadata to see if I need to read the whole file again. I only want to read again if the file changed.. My question now is if this a good use case for the clients (some other MS servers) and the MSs that serve this file to use etag or LastModified maybe? I think that I can use the last modified date and hash it as etag and it will be the same in all the MSs since its the same shared file.. but I will still need to implement the etag logic in the client servers and maybe use a shared cache between those clients with the etag right? Thanks in advance for your input ;)

How can we generate an Etag for a ressource PLEASE? in order to add it into a header's request abd avoid 412 HTTP errors? Thanks!

Hi Hussein , I was using etag in my work and came across with the doubt that what if we are caching server response in CDN in middle , in this case when browser sends etag with next request[If-None-Match] then this etag will be matched with CDN cached response? or how will it directly goto server for etag matching?

I have used etag by setting eTag property to true on the main web site under IIS, but when file changes, i still get the cached copy not the new one, any help with that please.

Hi Hussein, Hope you are doing well. Thank you for the last reply on Caching. I want to know why we use e-tag if we already have last modified(if modified since to check freshness of the resource) filed in http response. How e-tag's are calculated.

Thanks for explaining ! I have one query -as u said user first req n server will assign e-tag to him for that particular request. - wht if other user request same url as first. Will he get same etag which user 1 got or different? - what is rule of middleware thus middleware leads to cache poisoning even when E-Tag header is using ?

Done ✔️ thanks for knowledge 🙏

I will definitely use them. Looks like they are implemented by default in Nginx.

so what if you visit a different page, then etag tracking doesn't work?

Now, if ETags are used as zombie cookies, it will never return an update of the requested page right? Or is the response be configured on the server to send the content for every request regardless of the ETag?

Great video

I don't know if you have ever used AWS CloudFront but if you have is there anyway to incorporate E-Tags into this service and if so is there any advantage?

I was hoping the video to be on-point. :)

I get why to use them and I want to I cant seem to figure out how to generate them. Did I miss that part?

Thank youuuu

Why can't we use the page/resource hash as a tag? We will not have to deal with the load balancer problem. And we will eliminate the zombie cookies problem too.

please make a video, how http file upload works.

Hussein would this be the same be the of CDNs?

What is the alternative of eTag?

But if Hulu keeps sending you the same e-tag, then the client never sees the new index.html, no?

Where's the link to the concurrency?

why theher is that drum sound in the background? Tip: you can filter the unwanted sound by sampleling some seconds of video where you dont't say anything and then filtering out those frequencies

❤️

Thats for the video, I dont understand most of this etag crap, arent they like a hashed version of the response? For example if an http response object will return with json, then the server will get an etag number out of that? So each time the server needs to check if the etag is a match it has to reload the data to check? Or its cached somewhere or what the fuck?

This video could have been just 6 mins instead of 16 mins

Thanks for the explanation. But this video could have been much shorter. You basically say the same things over and over again

Man your videos are ok but you talk too much! you just make it too long for something can be explained in much shorter time.