Client caching is not working when load balancer is there

Question

I just wanted to know how client caching will work when load balancer is there ?

our deployment environment is like below

we have distributed 4 nodes will work as seperate instances these nodes connected to load balancer , but what problem we are facing is we have implimented client caching , when we are testing this client caching functionality what happens is when we test through nodes it works fine (for 1st request it shows 200 and next request it shows 304 ) but when we test through main URL it wont work (always shows 200)

Ex.

http://eclipse-retail-1n1.nat.bt.com/process/get_process.aspx?id=6555   x two times. (200 & 304)
http://eclipse-retail-1n2.nat.bt.com/process/get_process.aspx?id=6555   x two times. (200 & 304)
 
http://eclipse-retail-1n3.nat.bt.com/process/get_process.aspx?id=6555   x two times. (200 & 304)
http://eclipse-retail-1n4.nat.bt.com/process/get_process.aspx?id=6555   x two times. (200 & 304)
 
http://eclipse-retail-pilot.intra.bt.com/process/get_process.aspx?id=6555   (two times) (200 & 200)

Kindly help on this.

Answer 1

Hi,

Are you trying this on cloud or on-premise ? From my understanding you have enabled local caching on all the instances and if directly access the instance you are able to get the data and on going through load balancer it doesn't show the right data . 200 & 304 you mentioned are these two cache items stored ?And is the key for items hard coded or generated run time ?

Thanks

Arun

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arunks

Answer 2

we have not hard coded, it is generated run time . Let me explain in detail ..

we are fetching process details based process id , details will get displayed as XML in browser. so what we are doing is we have implemented client caching for fetching process.we are applying cache policy like below

        cachingPolicy.SetExpires(DateTime.UtcNow)
        cachingPolicy.SetMaxAge(New TimeSpan(0, 0, 0))
        cachingPolicy.SetCacheability(HttpCacheability.Public)
        cachingPolicy.SetOmitVaryStar(True)
        cachingPolicy.SetNoServerCaching()
        cachingPolicy.SetRevalidation(HttpCacheRevalidation.AllCaches)
        cachingPolicy.SetProxyMaxAge(New TimeSpan(0, 0, 0))
        cachingPolicy.SetNoTransforms()
        cachingPolicy.SetLastModified(contentModified)
        cachingPolicy.SetETag(ETag)
        cachingPolicy.SetValidUntilExpires(True)
        cachedDateKey = "pCreated" & strCache

when we deployed code into production environment if we browse through single nodes (Ex.http://eclipse-retail-1n1.nat.bt.com/process/get_process.aspx?id=6555) then for first request it shows HTTP status code 200 in fiddler and for 2nd request it shows 304 (works fine) but when we run it through main URL (Ex.http://eclipse-retail-pilot.intra.bt.com/process/get_process.aspx?id=6555) then it is showing HTTP status  code 200 always irrespective of no.of requests.