The ILogUIPlugin::OnProperties method is invoked by IIS when the administrator clicks Properties... on the site tab of the server Properties dialog in the MMC.
virtual HRESULT STDMETHODCALLTYPE OnProperties(
[IN] OLECHAR * pocMachineName, // name of machine on which server is running
[IN] OLECHAR * pocMetabasePath // metabase path to server
);
After your implementation of ILogUIPlugin::OnProperties completes execution, IIS will reload the instance of your custom logging module that is assigned to the affected Web or FTP server. This reload, which includes invocation of the custom logging module's ILogPlugin::InitializeLog and ILogPlugin::QueryExtraLoggingFields methods, allows your logging module to re-initialize itself with any values in the metabase that might have been changed by the user interface module.
ILogPlugin::InitializeLog, ILogPlugin::QueryExtraLoggingFields