I don’t understand the question.
SNA is System Network Architecture, a networking model with protocols somewhat like TCP/IP and its protocols. You use it when communicating with another system and you want (or need) to use SNA technologies. SSL is Secure Sockets Layer, a protocol used for securing communications across a TCP/IP network. You use it when communicating with another system and you want (or need) to encrypt the conversation.
In both cases, the other system must support the same functions.
In either case, you could enter [ sna ] or [ ssl ] into a Google search (or any search engine) and find out everything about them. The question is too general to get a useful answer. It’s not clear what you need to know.