CORBA

一．题目分析：
充分利用CORBA系统中对象的特点：接口的继承性，操作和属性自身的特点。通过两个实例分析COBRA内部实现结构。
二．配制环境JDK环境：


``

三.具体实现
题目一：Java版CORBA程序1——HelloWorld
1.编写IDL接口HelloWorld.idl
module sample{
interface HelloWorld{
wstring sayHello();
};
};
说明：CORBA处理字符串有：String和wstring两种类型，string类型主要用于处理ASCII类型的字符串，wstring用于处理多字节的字符串

2.编译IDL接口
编译结果生成sample包，生成下述文件
_HelloWorldStub.java
HelloWorld.java
HelloWorldHelper.java
HelloWorldHolder.java
HelloWorldOperations.java
HelloWorldPOA.java


3.编写并编译服务端程序:HelloWorldServer.java

import sample.*;
import org.omg.CosNaming.*;
import org.omg.CosNaming.NamingContextPackage.*;
import org.omg.CORBA.*;
import org.omg.CORBA.portable.*;
import org.omg.PortableServer.*;
class HelloWorldServant extends HelloWorldPOA{   //对象实现类
public String sayHello(){
return "\nHello World!17408070111孟婷婷\n";
}
}
public class HelloWorldServer{                  //服务程序
public static void main(String args[]){
try{
//初始化ORB
ORB orb = ORB.init(args, null);
//取根POA的引用
org.omg.CORBA.Object poaobj = orb.resolve_initial_references ("RootPOA");
org.omg.PortableServer.POA rootPOA = org.omg.PortableServer.POAHelper.narrow(poaobj);
org.omg.PortableServer.POAManager manager = rootPOA.the_POAManager();
//创建伺服对象 
HelloWorldServant objRef = new HelloWorldServant();
HelloWorld obj = objRef._this(orb);
//绑定命名服务 
NamingContext ncRef = NamingContextHelper.narrow(orb.resolve_initial_references("NameService"));
NameComponent nc = new NameComponent("Hello", ""); 
NameComponent path[] = {nc}; 
ncRef.rebind(path, obj);
//激活POA管理器 
manager.activate();
//等待处理客户程序的请求
System.out.println("HelloWorld is running!");
orb.run();
}catch (Exception e) { 
System.err.println("ERROR: " + e); 
e.printStackTrace(System.out); 
}
}
}

4.编写并编译客户端程序: HelloWorldClient.java

import sample.*; 
import org.omg.CosNaming.*; 
import org.omg.CORBA.*; 
public class HelloWorldClient { 
public static void main(String args[]) { 
try{
ORB orb = ORB.init(args, null);
org.omg.CORBA.Object objRef = orb.resolve_initial_references("NameService"); 
NamingContext ncRef = NamingContextHelper.narrow(objRef); 
NameComponent nc = new NameComponent("Hello",""); 
NameComponent path[] = {nc}; 
HelloWorld helloWorld = HelloWorldHelper.narrow(ncRef.resolve(path)); 
String hello = helloWorld.sayHello(); 
System.out.println(hello); 
} catch (Exception e) {
System.out.println("ERROR : " + e) ;
e.printStackTrace(System.out); 
}
}
}

5.运行
（1）启动名字服务器：
（2）启动服务端程序：

（3）启动客户端程序：

题目2.JAVA版CORBA程序2——Counter
编写实现连加、连减和加减混合等数学++/- -运算，并进行测试。
1 编写IDL接口counter.idl：
module CounterApp{
interface Counter{
readonly attribute long value;
void inc();
void dec();
};
};
2编译IDL接口：
编译结果生成CounterApp包，生成下述文件
_CounterStub.java
Counter.java
CounterHelper.java
CounterHolder.java
CounterOperations.java
CounterPOA.java


3 编写并编译对象实现代码：CounterImpl.java

4 编写并编译服务端程序: Server.java

import CounterApp.*;   
import java.io.*;   
import org.omg.CosNaming.*;
import org.omg.CosNaming.NamingContextPackage.*;
import org.omg.CORBA.*;
import org.omg.CORBA.portable.*;
import org.omg.PortableServer.*;
public class Server {
public static void main(String[] args){
try{
ORB orb = ORB.init(args, null);
org.omg.CORBA.Object poaobj = orb.resolve_initial_references ("RootPOA");
org.omg.PortableServer.POA rootPOA = org.omg.PortableServer.POAHelper.narrow(poaobj);
org.omg.PortableServer.POAManager manager = rootPOA.the_POAManager();
CounterImpl c_impl = new CounterImpl();
Counter c = c_impl._this(orb);
NamingContext ncRef = NamingContextHelper.narrow(orb.resolve_initial_references("NameService"));
NameComponent nc = new NameComponent("Count", "");
NameComponent path[] = {nc}; 
ncRef.rebind(path, c);
FileOutputStream file = new FileOutputStream("Counter.ref");
PrintWriter writer = new PrintWriter(file);
String ref = orb.object_to_string(c);
writer.println(ref);
writer.flush();
file.close();
System.out.println("Server started."+" Stop:Ctrl-c");
rootPOA.the_POAManager().activate();
orb.run();
}catch(IOException ex){
System.out.println("File error:"+ex.getMessage());
System.exit(2);
}catch(Exception ex){
System.out.println("Exception: "+ex.getMessage());
System.exit(1);
}
}
}

5 编写并编译客户端程序: Client.java

import CounterApp.*;  
import java.util.*;   
import java.io.*;   
import org.omg.CORBA.*; 
import org.omg.CosNaming.*; 
public class Client {   
     public static void main(String[] args){
        try{
           ORB orb = ORB.init(args, null);
           org.omg.CORBA.Object obj = orb.resolve_initial_references("NameService"); 
           NamingContext ncRef = NamingContextHelper.narrow(obj); 
           NameComponent nc = new NameComponent("Count",""); 
           NameComponent path[] = {nc};
           String ref = null; 
           try{
              Scanner reader = new Scanner(new File("Counter.ref"));   
              ref = reader.nextLine();
           }catch(IOException ex){
              System.out.println("File error: "+ex.getMessage());
              System.exit(2);
           }   
           obj = orb.string_to_object(ref);   
           if(obj == null){
              System.out.println("Invalid IOR");   
              System.exit(4);
           }   
           Counter c = null;   
           try{
              c = CounterHelper.narrow(obj);

           }catch(BAD_PARAM ex){
              System.out.println("Narrowing failed");
              System.exit(3);  
           }   
           int inp = -1;   
           do{
              System.out.print("Counter value: "+c.value()+"\nAction(+/-/e)?");   
              System.out.flush();   
              do{
                 try{
                    inp = System.in.read();
                 }catch(IOException ioe){
               }   
          }while(inp != '+' && inp != '-' && inp != 'e');   
          if(inp == '+')   c.inc();   
          else if(inp == '-')   c.dec();   
   }while(inp != 'e');  
}catch(Exception ex){
   System.out.println("Exception: "+ex.getMessage()); 
   System.exit(1);   
}  
}
}

6 运行
（1）启动名字服务器：
（2）启动服务端程序：

（3）启动客户端程序：实现自增自减

四．总结
这次上机主要了解了CORBA组件的编程方法，还是很顺利的，刚开始不知道怎么在cmd里改变目录，通过百度了解了，然后因为要输出名字所以在定义并编译对象接口的时候编写的是wstring