Protocols

Memcached supports a basic Text and Meta Text protocol. There is also a deprecated "binary" which no longer receives updates, but was used for a long time. The Meta protocol is more efficient than the binary protocol, is cross compatible with the Text protocol, and is recommended for all new clients.

• Text and Meta Protocol
• Meta Examples
• Binary Protocol
  • Slides on binary protocol by Toru Maesaka (2008)

Further, there are sub protocols and proposals

• SASL Authentication

Why is the binary protocol deprecated?

The binary protocol was introduced in 2008. It seemed like a good idea but it was not:

• Security issues
• Poor efficiency prevented adoption by large users
• Limited features and poor extensibility
• SASL authentication rarely worked and caused a lot of support headaches.
• Difficult to implement

We introduced the meta protocol in 2019:

• Better wire efficiency
• More features (anti-stampeding herd, stale-while-revalidate, etc)
• Small command set (get/set/delete/math)
• Extensible (flags and tokens)
• Simple and easy to implement

More information can be found in protocol.txt linked above.