Forms can get information such as product descriptions, prices, and pictures from databases or other systems and enter it in the form for you. Web services make filling out a form easier and more accurate.
Form authors add web service calls when creating forms using
To perform a lookup using a web service:
When the web service finds a result, the field is populated with appropriate information.
NOTE If you click a button such as Save before the lookup is complete, the form is not saved until the lookup is complete.