| 在Oracle 8i中,往往会出现要在存储过程中运行操作系统命令的情况.一般来说,利用Oracle Enterprise Manager设定作业时可以达到这个目的.但是由于OEM在设定作业缺乏灵活性,设定的作业的参数是固定的.在实际应用当中往往需要在SQL语句当中运行需要随时运行操作系统命令.Oracle 8i没有直接运行OS命令的语句,我们可以利用DBMS_PIPE程序包实现这一要求. |
| DBMS_PIPE通过创建管道,可以让至少两个进程进行通信.Oracle的管道与操作系统的管道在概念上有相同的地方,但是在实现机制不同. |
| 下面介绍实现具体步骤: |
| 1 创建一个程序包,姑且起名叫DAEMON,SQL语句如下: |
| /*创建daemon程序包*/ |
| CREATE OR REPLACE PACKAGE BODY daemon AS |
| /*execute_system是实现运行os命令的函数*/ |
| FUNCTION execute_system(command VARCHAR2, |
| timeout NUMBER DEFAULT 10) |
| RETURN NUMBER IS |
| status NUMBER; |
| result VARCHAR2(20); |
| command_code NUMBER; |
| pipe_name VARCHAR2(30); |
| BEGIN |
| pipe_name := DBMS_PIPE.UNIQUE_SESSION_NAME; |
| DBMS_PIPE.PACK_MESSAGE('SYSTEM'); |
| DBMS_PIPE.PACK_MESSAGE(pipe_name); |
| DBMS_PIPE.PACK_MESSAGE(command); |
| /*向daemon管道发送表示命令的字符*/ |
| status := DBMS_PIPE.SEND_MESSAGE('daemon', timeout); |
| IF status <> 0 THEN |
| RAISE_APPLICATION_ERROR(-20010, |
| 'Execute_system: Error while sending. Status = ' || status); |
| END IF; |
| status := DBMS_PIPE.RECEIVE_MESSAGE(pipe_name, timeout); |
| IF status <> 0 THEN |
| RAISE_APPLICATION_ERROR(-20011, |
| 'Execute_system: Error while receiving. |
| Status = ' || status); |
| END IF; |
| /*获取返回结果*/ |
| DBMS_PIPE.UNPACK_MESSAGE(result); |
| IF result <> 'done' THEN |
| RAISE_APPLICATION_ERROR(-20012, |
| 'Execute_system: Done not received.'); |
| END IF; |
| DBMS_PIPE.UNPACK_MESSAGE(command_code); |
| DBMS_OUTPUT.PUT_LINE('System command executed. result = ' || |
| command_code); |
| RETURN command_code; |
| END execute_system; |
| /*stop是让daemon停止*/ |
| PROCEDURE stop(timeout NUMBER DEFAULT 10) IS |
| status NUMBER; |
| BEGIN |
| DBMS_PIPE.PACK_MESSAGE('STOP'); |
| status := DBMS_PIPE.SEND_MESSAGE('daemon', timeout); |
| IF status <> 0 THEN |
| RAISE_APPLICATION_ERROR(-20030, |
| 'stop: error while sending. status = ' || status); |
| END IF; |
| END stop; |
| END daemon; |
| 通过Sql*Plus运行以上语句,将为当前用户创建daemon程序包. |
| 2 创建在OS上运行的守护进程,监听由上面的daemon程序包发来的要求执行os命令的语句.以下Pro*C的代码,必须由pro*c先进行预编译. |
| #include |
| #include |
| EXEC SQL INCLUDE SQLCA; |
| EXEC SQL BEGIN DECLARE SECTION; |
| char *uid = "scott/tiger";/*在这个地方改为你自己访问的用户,密码,服务名*/ |
| int status; |
| VARCHAR command[20]; |
| VARCHAR value[2000]; |
| VARCHAR return_name[30]; |
| EXEC SQL END DECLARE SECTION; |
| void |
| connect_error() |
| { |
| char msg_buffer[512]; |
| int msg_length; |
| int buffer_size = 512; |
| EXEC SQL WHENEVER SQLERROR CONTINUE; |
| sqlglm(msg_buffer, &buffer_size, &msg_length); |
| printf("Daemon error while connecting:/n"); |
| printf("%.*s/n", msg_length, msg_buffer); |
| printf("Daemon quitting./n"); |
| exit(1); |
| } |
| void |
| sql_error() |
| { |
| char msg_buffer[512]; |
| int msg_length; |
| int buffer_size = 512; |
| EXEC SQL WHENEVER SQLERROR CONTINUE; |
| sqlglm(msg_buffer, &buffer_size, &msg_length); |
| printf("Daemon error while executing:/n"); |
| printf("%.*s/n", msg_length, msg_buffer); |
| printf("Daemon continuing./n"); |
| } |
| main() |
| { |
| EXEC SQL WHENEVER SQLERROR DO connect_error(); |
| EXEC SQL CONNECT :uid; |
| printf("Daemon connected./n"); |
| EXEC SQL WHENEVER SQLERROR DO sql_error(); |
| printf("Daemon waiting.../n"); |
| while (1) { |
| EXEC SQL EXECUTE |
| BEGIN |
| /*接收deamon发来的字符*/ |
| :status := DBMS_PIPE.RECEIVE_MESSAGE('daemon'); |
| IF :status = 0 THEN |
| /*取出字符*/ |
| DBMS_PIPE.UNPACK_MESSAGE(:command); |
| END IF; |
| END; |
| END-EXEC; |
| IF (status == 0) |
| { |
| command.arr[command.len] = '/0'; |
| /*如果是stop,该进程就退出*/ |
| IF (!strcmp((char *) command.arr, "STOP")) |
| { |
| printf("Daemon exiting./n"); |
| break; |
| } |
| ELSE IF (!strcmp((char *) command.arr, "SYSTEM")) |
| { |
| EXEC SQL EXECUTE |
| BEGIN |
| DBMS_PIPE.UNPACK_MESSAGE(:return_name); |
| DBMS_PIPE.UNPACK_MESSAGE(:value); |
| END; |
| END-EXEC; |
| value.arr[value.len] = '/0'; |
| printf("Will execute system command '%s'/n", value.arr); |
| /*运行os命令*/ |
| status = system(value.arr); |
| EXEC SQL EXECUTE |
| BEGIN |
| DBMS_PIPE.PACK_MESSAGE('done'); |
| DBMS_PIPE.PACK_MESSAGE(:status); |
| :status := DBMS_PIPE.SEND_MESSAGE(:return_name); |
| END; |
| END-EXEC; |
| IF (status) |
| { |
| printf |
| ("Daemon error while responding to system command."); |
| printf(" status: %d/n", status); |
| } |
| } |
| ELSE |
| { |
| printf |
| ("Daemon error: invalid command '%s' received./n", |
| command.arr); |
| } |
| } |
| ELSE |
| { |
| printf("Daemon error while waiting for signal."); |
| printf(" status = %d/n", status); |
| } |
| } |
| EXEC SQL COMMIT WORK RELEASE; |
| exit(0); |
| } |
| 以上代码起名为daemon.pc,用proc预编译: |
| proc iname=daemon.pc userid=用户名/密码@服务名 sqlcheck=semantics |
| 得到daemon.c,在用c进行编译,注意在NT上要把orasql8.lib加上,否则编译通过,连接没法通过. |
| 3 在服务器上运行daemon.exe |
| 4 在sqlplus运行测试语句: |
| SQL> variable rv number |
| SQL> execute :rv := DAEMON.EXECUTE_SYSTEM('ls -la'); |
| PL/SQL 过程已成功完成。 |
| SQL> execute :rv := DAEMON.EXECUTE_SYSTEM('dir'); |
| PL/SQL 过程已成功完成。 |
| SQL> |
| DBMS_PIPE的用法见oracle的文档. |
