Which two feature characteristics are associated with RESTful APIs?

In the context of RESTful APIs, the characteristic of being stateless is fundamental. This means that each API call from a client to the server must contain all the information necessary to understand and process the request. The server does not retain any session information between requests. This design choice simplifies the scalability of the API as it allows for easier load balancing and improves the ability to manage resources effectively.

The term "uni-directional" generally refers to the flow of communication being one-way—from client to server in the case of a RESTful API request, and then back to the client with a response. While there can be interactions that appear bi-directional through the exchange of requests and responses, the nature of REST APIs is such that each interaction operates independently, emphasizing the request and response model.

This understanding supports that the characteristics of statelessness and a uni-directional flow align with how RESTful APIs are designed and function, distinguishing them from other types of APIs that may maintain state or support more complex communication patterns.