AJAX :: WebResource Fail To Work Under Reverse Proxy?

We have an issue when our web application runs under reverse proxy.

The reverse proxy change the URL for the website from for example: "http://TestWebApp/" to: "http://ProxyDomain/Test/" when it runs under reverse proxy which is mapped to "http://TestWebApp/" and rout requests to it.

This raise an issue of root relative paths (paths that start with "/" to be relative to the root of the web application i.e. "/Folder1/Test.aspx"). Generally all paths that need to be rendered to client we use ResolveClientUrl method and all is good.

When using Ajax controls and ScriptManager WebResource.axd paths are rendered in script tags as a relative url paths ("/WebResource.axd?blablabla") because the root under reverse proxy is the proxy domain itself the path is useless - the web resouce is not downloaded and the application break.

To fix this we tried to set a Response.Filter in OnPreRender event handler of our base page. In our custom filter we use Regex to search and replace all "/WebResource.axd" occurences with the resolved to client root path using the ResolveClientUrl method of the page. This works great and the web resources are downloaded to client.

But this is not the end of our troubles.

In Ajax requests the response output is fixed as described but when recieved at the client end it is not valid and the partial update fails with Sys.WebForms.PageRequestManagerParserErrorException.

It fails to parse the response because the rendered response have numbers that states the actual count of bytes per rendered component (which includes the script tags referencing the WebResource.axd). The client reciever validates the recieved response according to the numbers, but, our filter altered the response so the numbers are not correct and the response validation fails.

We can try and code a smart filter that parse the response and recalculate the numbers according to the ammount of paths fixed, but I hope there is an elegant and better solution for this.