Erlang and OTP in Action.pdf - Synrc

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This function pattern matches on the initial line of the HTTP message in order to figure
out what operation was performed and to capture the request URI information. It then
performs the appropriate simple_cache function and creates a response message.
We have now implemented all of the protocols we mentioned in the first part of this
chapter. Our text interface does not give us much freedom with regard to what we can store
in the cache. It is pretty limited, which is fine for storing certain types of data. It has the
benefit that it is pretty easy to implement and use. Our second protocol, the REST based
protocol, puts the full power of HTTP at our disposal for transporting data into and out of our
cache.
11.3 – Summary
The simple cache is now capable of talking with external clients through two different
protocols, our custom text based protocol and the more structured RESTful interface. Along
the way we learned a very important technique/pattern for creating a concurrent TCP server,
enough HTTP to be dangerous, and we rounded out our coverage of behaviors with the
gen_fsm. This work has made it possible for the simple cache to be used in production
environments outside of an Erlang shop which is certainly useful in today’s “right tool for the
right job” multi-language and multi-platform production environments. In the next chapter,
we will cover how to get Erlang to interact directly with other languages like, C, Java to give
you the skills for even tighter multi-language communication.
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