ASP.NET + Configuring Entity Tags

Question

Hello,

I have developed an ASP.NET web application that I'm working on putting the finishing touches on. To assist with this, I have been using YSlow. With this tool, I have discovered that I have not properly configured the entity tags of the components on my pages. Unfortunately, I have no idea how to do this.

How do I configure entity tags on components within an ASP.NET page?

Here is what YSlow says:

There are 28 components with misconfigured ETags http://localhost:81/resources/page.js http://localhost:81/resources/images/bg.png http://localhost:81/resources/images/app.png ...

Entity tags (ETags) are a mechanism web servers and the browser use to determine whether a component in the browser's cache matches one on the origin server. Since ETags are typically constructed using attributes that make them unique to a specific server hosting a site, the tags will not match when a browser gets the original component from one server and later tries to validate that component on a different server.

Thank you!

Answer 1

This is not really an ASP.NET issue since ETags (at least by default) are emitted by IIS in response to requests for static files. The few examples you've given are all static files (JS, PNG, etc).

Exactly why your ETags are misconfigured is difficult to say but, at a guess, I'd say you're hosting your site in a web farm (more than one web serer) and each server is generating its ow ETag and thus making them less than useful.

See here for some more info: http://developer.yahoo.net/blog/archives/2007/07/high_performanc_11.html