The Application Servers

Our application has two servers: a prime number server and an area server.

The Prime Number Server

Here’s the prime number server. It has been written using the gen_server behavior (see Getting Started with gen_server). Note how it includes the alarm handling procedures we developed in the previous section.

prime_server.erl
 
-module​(prime_server).
 
 
-behaviour​(gen_server).
 
 
-export​([new_prime/1, start_link/0]).
 
 
%% gen_server callbacks
 
-export​([init/1, handle_call/3, handle_cast/2, handle_info/2,
 
terminate/2, code_change/3]).
 
 
start_link() ->
 
gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
 
 
new_prime(N) ->
 
%% 20000 is a timeout (ms)
 
gen_server:call(?MODULE, {prime, N}, 20000). ...

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