I'm trying to make use of web services in an ASP.NET application I'm developing; currently I have a service running that I call form the client side to run AJAX queries against my database as textboxes are updated. This all works a treat. I am using the ASP.NET ScriptManager not jQuery ajax or any other third party tools.
I also need to make use of the logic in the web service elsewhere in the application - specifically if the page that uses it from the client gets posted back to the server (if a drop-down is changed) a lot of the calculated values need to be changed. It seems silly to duplicate the code in code-behind - is there a way I can access the existing service to do the calculations?
I've had a look at some other questions, but they talk a lot about SOAP, REST, Endpoints and Bindings, and I really don't understand a word of it! Some general advice or a pointer in the right direction would be great.