basic auth for xmlrpc

HTTP auth should be handled by your web server. Unless you're using tracd, it's not handled by any component of Trac.

This is clearly a duplicate, as you mentioned in the description.

HttpAuthPlugin handles it for certain urls, if using AccountManager. According to the description without using webserver authentication.

could it be that authplugin should pop up its auth form for any url within the /login namespace, or somehow not? and then HttpAuthPlugin would also work for the url /login/xmlrpc?

HttpAuthPlugin seems to work for urls outside the /login namespace, like the default /xmlrpc configuration. just with /login/xmlrpc both plugins somehow prevent bringing up the basic auth window. and thats the url suggest by XmlRpcPlugin for authenticated access.

a clear statement which of the three components would be responsible for solving the issue would be very helpful. but we think "webserver" would not be the solution, as we HttpAuthPlugin would be pointless then.

Ok, I was confusing the HttpAuthPlugin with the AuthFormPlugin. It does appear that this can be handled by the HttpAuthPlugin.