Hello, I am also interested in this since we have a proprietary document repository, and to use the Pega Requirements Portal, it requires us to CMIS. When we try to use the default configuration of where to place the files that are uploaded, it still defaults to CMIS. Any ideas on how to configure CMIS to use either a rest call or some other way to upload the files?
CMIS is an interface standard http://docs.oasis-open.org/cmis/CMIS/v1.1/CMIS-v1.1.html.
If your repository is not supporting this standard you will need to implement the interface you need yourself. For rest and soap for instance you could define connectors using the wizards in Pega.
If i understand your question correctly you are looking for extention points to implement the proprietary interface calls.
To do this you can look into the activities and logic in the link-Attachment and Data-Workattach classes.
For storing files look into pySaveFileContent activity. This one is triggered by a declare trigger when a data workattach record is saved. Depending on if cmis is enabled or not it will store the content in the CMIS repository. Like storing there is an equivalent for removing files from the repository.
I think you should create a setting yourself for your propriety interface and find the extentionpoints where CMIS would be called and instead trigger your own interface calls.
Unfortunately there is no easy switch here. Its going to need some investigation/study to understand how the attachment logic is linked together.