为了演示需要，我们将前面几节中 messager 程序分布到五个文件中：
mess_config.hrl
配置所需数据头文件
mess_interface.hrl
客户端与 messager 之间的接口定义
user_interface.erl
用户接口函数
mess_client.erl
messager 系统客户端的函数
mess_server.erl
messager 服务端的函数
除了完成上述工作外，我们使用记录重新定义了 shell 、客户端以及服务端的消息格式。此外，我们还引入了下面这些宏：
| %%%----FILE mess_config.hrl---- |
| %%% Configure the location of the server node, |
| -define(server_node, messenger@super). |
| %%%----END FILE---- |
| %%%----FILE mess_interface.hrl---- |
| %%%Message interface between client and server and client shell for |
| %%% messenger program |
| %%%Messages from Client to server received in server/1 function. |
| -record(logon,{client_pid, username}). |
| -record(message,{client_pid, to_name, message}). |
| %%% {'EXIT', ClientPid, Reason} (client terminated or unreachable. |
| %%% Messages from Server to Client, received in await_result/0 function |
| -record(abort_client,{message}). |
| %%% Messages are: user_exists_at_other_node, |
| %%% you_are_not_logged_on |
| -record(server_reply,{message}). |
| %%% Messages are: logged_on |
| %%% receiver_not_found |
| %%% sent (Message has been sent (no guarantee) |
| %%% Messages from Server to Client received in client/1 function |
| -record(message_from,{from_name, message}). |
| %%% Messages from shell to Client received in client/1 function |
| %%% spawn(mess_client, client, [server_node(), Name]) |
| -record(message_to,{to_name, message}). |
| %%% logoff |
| %%%----END FILE---- |
| %%%----FILE mess_interface.hrl---- |
| %%% Message interface between client and server and client shell for |
| %%% messenger program |
| %%%Messages from Client to server received in server/1 function. |
| -record(logon,{client_pid, username}). |
| -record(message,{client_pid, to_name, message}). |
| %%% {'EXIT', ClientPid, Reason} (client terminated or unreachable. |
| %%% Messages from Server to Client, received in await_result/0 function |
| -record(abort_client,{message}). |
| %%% Messages are: user_exists_at_other_node, |
| %%% you_are_not_logged_on |
| -record(server_reply,{message}). |
| %%% Messages are: logged_on |
| %%% receiver_not_found |
| %%% sent (Message has been sent (no guarantee) |
| %%% Messages from Server to Client received in client/1 function |
| -record(message_from,{from_name, message}). |
| %%% Messages from shell to Client received in client/1 function |
| %%% spawn(mess_client, client, [server_node(), Name]) |
| -record(message_to,{to_name, message}). |
| %%% logoff |
| %%%----END FILE---- |
| %%%----FILE mess_client.erl---- |
| %%% The client process which runs on each user node |
| -module(mess_client). |
| -export([client/2]). |
| -include("mess_interface.hrl"). |
| client(Server_Node, Name) -> |
| {messenger, Server_Node} ! #logon{client_pid=self(), username=Name}, |
| await_result(), |
| client(Server_Node). |
| client(Server_Node) -> |
| receive |
| logoff -> |
| exit(normal); |
| #message_to{to_name=ToName, message=Message} -> |
| {messenger, Server_Node} ! |
| #message{client_pid=self(), to_name=ToName, message=Message}, |
| await_result(); |
| {message_from, FromName, Message} -> |
| io:format("Message from ~p: ~p~n", [FromName, Message]) |
| end, |
| client(Server_Node). |
| %%% wait for a response from the server |
| await_result() -> |
| receive |
| #abort_client{message=Why} -> |
| io:format("~p~n", [Why]), |
| exit(normal); |
| #server_reply{message=What} -> |
| io:format("~p~n", [What]) |
| after 5000 -> |
| io:format("No response from server~n", []), |
| exit(timeout) |
| end. |
| %%%----END FILE--- |
| %%%----FILE mess_server.erl---- |
| %%% This is the server process of the messenger service |
| -module(mess_server). |
| -export([start_server/0, server/0]). |
| -include("mess_interface.hrl"). |
| server() -> |
| process_flag(trap_exit, true), |
| server([]). |
| %%% the user list has the format [{ClientPid1, Name1},{ClientPid22, Name2},...] |
| server(User_List) -> |
| io:format("User list = ~p~n", [User_List]), |
| receive |
| #logon{client_pid=From, username=Name} -> |
| New_User_List = server_logon(From, Name, User_List), |
| server(New_User_List); |
| {'EXIT', From, _} -> |
| New_User_List = server_logoff(From, User_List), |
| server(New_User_List); |
| #message{client_pid=From, to_name=To, message=Message} -> |
| server_transfer(From, To, Message, User_List), |
| server(User_List) |
| end. |
| %%% Start the server |
| start_server() -> |
| register(messenger, spawn(?MODULE, server, [])). |
| %%% Server adds a new user to the user list |
| server_logon(From, Name, User_List) -> |
| %% check if logged on anywhere else |
| case lists:keymember(Name, 2, User_List) of |
| true -> |
| From ! #abort_client{message=user_exists_at_other_node}, |
| User_List; |
| false -> |
| From ! #server_reply{message=logged_on}, |
| link(From), |
| [{From, Name} | User_List] %add user to the list |
| end. |
| %%% Server deletes a user from the user list |
| server_logoff(From, User_List) -> |
| lists:keydelete(From, 1, User_List). |
| %%% Server transfers a message between user |
| server_transfer(From, To, Message, User_List) -> |
| %% check that the user is logged on and who he is |
| case lists:keysearch(From, 1, User_List) of |
| false -> |
| From ! #abort_client{message=you_are_not_logged_on}; |
| {value, {_, Name}} -> |
| server_transfer(From, Name, To, Message, User_List) |
| end. |
| %%% If the user exists, send the message |
| server_transfer(From, Name, To, Message, User_List) -> |
| %% Find the receiver and send the message |
| case lists:keysearch(To, 2, User_List) of |
| false -> |
| From ! #server_reply{message=receiver_not_found}; |
| {value, {ToPid, To}} -> |
| ToPid ! #message_from{from_name=Name, message=Message}, |
| From ! #server_reply{message=sent} |
| end. |
| %%%----END FILE--- |
