erlang客户端程序学习（一）

最新推荐文章于 2024-06-12 09:50:25 发布

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本文介绍了一个使用Erlang实现的简单面积计算服务，该服务可以计算矩形和圆形的面积，并通过RPC方式进行调用。经过多次改进，最终实现了更高效稳定的远程过程调用。

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area_server.erl

-module(area_server). -export([loop/0]). loop() -> receive {rectangle, Width, Ht} -> io:format("Area of rectangle is ~p~n", [Width * Ht]), loop(); {circle, R} -> io:format("Area of circle is ~p~n", [3.14*R*R]), loop(); Other -> io:format("I do not know what the area of a ~p is ~n", [Other]), loop() end.

测试过程：
1> c(area_server).
{ok,area_server}
2> Pid = spawn(fun area_server:loop/0).
<0.39.0>
3> Pid ! {circle, 67}.
Area of circle is 14095.46
{circle,67}

第一次改进：

-module(area_server). -export([loop/0, rpc/2]). rpc(Pid, Request) -> Pid ! {self(), Request}, receive Response -> Response end. loop() -> receive {From, {rectangle, Width, Ht}} -> From ! {rectangle, Width*Ht}, loop(); {From, {circle, R}} -> From ! {circle, 3.14*R*R}, loop(); {From, Other} -> Error = "Sorry, error!", From ! {Error,Other}, loop() end.

测试：
4> c(area_server).
{ok,area_server}
6> Pid = spawn(fun area_server:loop/0).
<0.53.0>
7> area_server:rpc(Pid, sockes).
{"Sorry, error!",sockes,ok}

改进2：

-module(area_server). -export([loop/0, rpc/2]). rpc(Pid, Request) -> Pid ! {self(), Request}, receive {Pid, Response} -> Response end. loop() -> receive {From, {rectangle, Width, Ht}} -> From ! {self(), Width*Ht}, loop(); {From, {circle, R}} -> From ! {self(), 3.14*R*R}, loop(); {From,Other} -> From ! {self(), error, Other}, loop() end.

测试：
2> c(area_server).
{ok,area_server}
3> Pid = spawn(fun area_server:loop/0).
<0.43.0>
4> area_server:rpc(Pid, {rectangle, 8, 6}).
48
改进3：

-module(area_server). -export([start/0]). start() -> Pid = spawn(fun loop/0), rpc(Pid, {rectangle, 8, 6}). rpc(Pid, Request) -> Pid ! {self(), Request}, receive {Pid, Response} -> Response end. loop() -> receive {From, {rectangle, Width, Ht}} -> From ! {self(), Width*Ht}, loop(); {From, {circle, R}} -> From ! {self(), 3.14*R*R}, loop(); {From,Other} -> From ! {self(), error, Other}, loop() end.