Learn from Memcached’s Success

Memcached becomes more and more popular nowadays. It is widely used by many heavy loaded sites. Why does it succeed? Well, of course the first and the most important reason is that it meets the need for speed of the web 2.0 sites, by cachi

Memcached becomes more and more popular nowadays. It is widely used by many heavy loaded sites. Why does it succeed?

Well, of course the first and the most important reason is that it meets the need for speed of the web 2.0 sites, by caching data and objects in memory. However, from the point of view of a server developer, what I want to emphasize is that it is the simplicity of memcached’s protocol design makes it more successful. Take a look at memcached’s protocol:

storage: ("set", "add", "replace", "append", "prepend", "cas")
          [noreply]rn
         cas [noreply]rn
     reply: ("ERRORrn", "CLIENT_ERROR rn", "SERVER_ERROR rn",
         "STOREDrn", "NOT_FOUNDrn", "EXISTSrn", "NOT_FOUNDrn")

retrieval: ("get", "gets")
         get rn
         gets rn
     reply: ("ENDrn",
         "VALUE []rnrn")

deletion:
         delete [] [noreply]rn
     reply: ("DELETEDrn", "NOT_FOUNDrn")

increment/decrement: ("incr", "decr")
         incr [noreply]rn
         decr [noreply]rn
     reply: ("NOT_FOUNDrn",
         "rn")

statistics: ("stat")
         statsrn
         stats rn
     reply: ("STAT rn",
         "STAT items:: rn"
         "ENDrn")

other:
     flush_all
     reply: ("OKrn")
     versionrn
     reply: ("VERSION rn")
     verbosity
     reply: ("OKrn")
     quit

With the textual protocol as shown above, memcache can be easily supported and implemented in various programming languages. No wonder dozens of different memcache clients appear. And then it consequently boosts memcached’s use. Simple thing usually will withstand the test of time. The old simple textual protocols, e.g., HTTP, FTP, SMTP and POP3 are still in use on the modern Internet. Not only because textual protocols can be easily parsed and extended, but also they are convenient for human being to read and debug. This is where the UNIX philosophy shines.

In conclusion, always prefer textual protocol when designing your own application. It would turn out to be really a wise decision.

原文地址：Learn from Memcached’s Success, 感谢原作者分享。