Which of the following is NOT a common method for performing integration over HTTP in Appian?

The correct answer is that FTP - Transfer File is not a common method for performing integration over HTTP in Appian. This is primarily because FTP (File Transfer Protocol) is a protocol used for transferring files rather than facilitating HTTP-based integrations. Appian is more focused on modern web service interactions, which are typically conducted using HTTP-based protocols like REST and SOAP.

REST and SOAP are well-supported in Appian for integrating with external systems over HTTP. REST integrations allow for lightweight and stateless communication, while SOAP provides a structured and standards-based approach to web services. GraphQL, while not as traditional as REST or SOAP, is increasingly recognized for querying APIs in a flexible manner, and Appian has mechanisms to integrate with GraphQL endpoints as well.

In contrast, FTP is not designed for the same use cases as the other protocols mentioned; rather, it serves a different function focused on file transfers, which is outside the realm of HTTP-based API integrations typically utilized in Appian workflows and applications. Hence, this makes it the option that is not commonly associated with HTTP integration methods in the Appian platform.