How to trigger change of a jcr:content page and get the change data?

I created two apps name as web1 and web2. In the web1 has some page (page1, page2, page3, ...). In the web2 has some page (page21, page22, page23, ...). I want to trigger the jcr:content in the web1 and get the change data to update for the page on web2.

Example: When I modify page1 in the web1. I want to get the change data of jcr:content of page1. So update the change data of page1 in the web1 for the page21 in the web2 for the same field.

How to do that?

Thanks & kind regards,

BHOANG