I am implementing for an approach to integrate from Salesforce to our 3rd party system. Usually our customer has a large set of Contact data and they want to integrate to our system. Meanwhile, our system need to generate our Id and store back as an external Id into Salesforce.
When data amount is small this is quite achievable via Request & Response mode. However, when the quantity is large, Salesforce has various limits - SOQL, DML, etc. So what is the suggested approach in achieving this?