Question

Let’s say I want to write an FTP client from scratch. In the command channel various status and error codes can be passed between server and client such as :

• 200 Command okay
• 331 User name okay, need password
• 421 Service not available
• …

Ideally, the numeric code and a human-readable message should be kept.

How should these be represented ? As an enum in some sort of Connection class ? What could be done to accomodate different messages or new codes ?

Answer 1

I would prefer the enums with some logic contains:

public enum FTPReturnCode {
     OKAY(200), NAME_OK_PW_NEEDED(331), ... ;
}

Since the FTP doesn’t change since 1985 (rfc959), you can add all FTP response codes into the enum class.