ABAP Code for USA ESS Addresses (Interactive Forms)

Hi,

Good day to everyone. Am a beginner in ABAP. Would like to ask expertise here questions. Am doing ESS Services for US Addresses. The services is implemented in Adobe Interactive Forms. However, coding need to be ABAP. Because validations have to run in backend. Therefore, FormCal/Javascript cannot be use in Adobe Interactive Form. There are some validations require in BADI. This is first time coding ABAP. Therefore, not sure how to implement it. Below are the validations require. Hope expertise here can provide code/resolution.

1. Address Line 1 and Line 2 length. The length cannot exceed 20 characters. If exceed, error message will display.

2. Mandatory fields. Address Line 1, City, State and Zipcode. These are mandatory fields. Validations require to check whether it's fill-in.

3. City or State change. It'll compare user entered value with current store value. If there is changes, it'll pop up a window. This window can contains URL, message and button.

4. ZipCode Validation. It'll check whether zipcode enter is valid.

Hope to hear from expertise soon.

Thank You,

Aaron