I have looked into the iis logs and can see a post verb for calls made to asmx services. Is there any way to identify the parameters passed when calling the web methods. I am analysing an application in production and this information will be really useful. While no code changes can be made, I have permissions to change iis log settings.
IIS includes no ability in its logging to log POST fields (or the content of the request body).
To log that kind of data, easiest to add to to the web application's (ie. global.asax) BeginRequest event.
If you have receiving significant data (eg. file uploads) you might want to think about how much data that will generate.