CAIPS stands for “Computer Assisted Immigration Processing System” and contains all the determinations made by a visa officer reviewing your file, as well as concerns the visa officer may have.
CAIPS allows you to see issues with your application which you can quickly address by communication with the office handling your immigration application.
If you are scheduled for an interview you should get your CAIPS which will likely reveal why the interview was called and which concerns the visa officer will raise with you.
Citizenship and Immigration Canada will only send CAIPS to a Canadian address or to a representative in Canada. If you are not in Canada there are several firms who will obtain CAIPS for you for a fee.