ArcGIS Server site: poor cache efficiency due to different "etag" header sent according to machine

NicolasGIS

Hello,

When refreshing my web application, I was surprised not to only hit '304 Not Modified' responses when querying my ArcGIS Server services for the layer properties with the following URL:

https://gis.company.com/arcgis/rest/services/General/Data/MapServer/86?f=json&token=Foo

What I noticed is that if you query your ArcGIS Server VM individually:

https://gisVM01.company.com:6443/arcgis/rest/services/General/Data/MapServer/86?f=json&token=Foo

https://gisVM02.company.com:6443/arcgis/rest/services/General/Data/MapServer/86?f=json&token=Foo

and compare the responses, they are identical (to notepad at least) but they both have a different "Etag" header.

As a consequence, cache cannot be leverage.

It looks like ArcGIS Server machine is creating the Etag header by taking into account specific properties to the VM. As I am hitting my servers in a round robin way behind a load balancer, I always have 50% layers responses with 304 Not modified and 200.

Do you observe the same phenomena ?

Thanks

JoshuaBixby

The way you worded your question, it makes me believe you are not using ArcGIS Web Adaptors, is that correct?

NicolasGIS

Hi,

No, I am using webadaptor on each VM and there is a front load balancer.

Don’t think the issue is related to WebAdaptor as you can replicate when by passing it it.

Hope it is clearer