Magento : How to do share cart between different domain

Question

I have tried share-cart between different domain but it isn't working.

I have two websites with different domains like

https://www.site1.com

and

http://www.site2.com

I want to share this website cart data

https://www.site1.com

to

http://www.site2.com

I have tried it but not working for me.

If you have any idea about this please share with me.

Thanks in advance.