We have an external CRM system. We are trying to pull in campaigns and open & click events and correlate them. I'm able to retrieve Open events and Click events via the SOAP API and can retrieve Campaigns via the REST API. But is it possible to tie the open and click events to a specific campaign? I can't quite figure out the link between them.
You'll have to use a combination of the REST APIs and SOAP API.
You'll get the campaign and campaign assets back using these two REST routes:
After you get the campaign assets back, you'll then want to use the send summary in the SOAP API to get back a batch of SendIDs filtered (probably a SimpleFilterPart) by the ObjectIDs that the REST route gave you.
After that, you can use the SendIDs for each send to get back the opens and clicks via SOAP.
Hope this helps!