The system types, the error handling mechanisms, and the data volume and processing volume are three constraints and pain-points that an integration architect should consider when choosingthe integration pattern
/mechanism. The system types determine what kind of interfaces and protocols are available or required for the integration, such as APIs, file systems, email, etc. The error handling mechanisms ensure that the integration can handleany failures or exceptions gracefully and provide appropriate logging and notification.
The data volume and processing volume affect the performance and scalability of the integration, as well as the choice of synchronous or asynchronous methods. Reference: Salesforce Integration Architecture Designer Resource Guide, page 17