MAIN MENU BIODATA ASSIGNMENTS TUTORIALS EMAILS
DISTRIBUTED SYSTEMS (TCT 2034)
ASSIGNMENT 5
( CORBA )
QUESTION:
Insert 3 things in the interface that is Stock Code, Stock Name and Price.
Answer 1:
1. Create IDL file
//Stock.idl
module Stock {
readonly attribute string code;
attribute string name;
attribute double price;
};
};
------------------------------------------------------------------------------------------------------------
2. Implement the interfaces
class StockItemServant extends _StockItemImplBase
{
//Declare the initialize instance variable…
private String code = “”;
private String name = “ ”;
private double price = “”;
//Constructor…
public StockItemServer(String newcode, Sring newname, double newprice)
{
code = newCode;
name = newName;
price = newPrice;
}
//Must supply the following ‘get’ and ‘set’ methods…
//Accessor method(‘get’ method) for stock code…
public String code();
{
return code;
}
//Accessor method(‘get’ method) for stock name…
public String name();
{
return name;
}
//Accessor method(‘get’ method) for stock price…
public double price();
{
return price;
}
}
class StockItemFactoryServant
extends _StockItemFactoryImplBase
{
//Method to create a StockItemServant object and return a
//reference to this object (allowing clients to create
//StockItem objects on the servant)…
public StockItem CreateItemServant(newcode, newName, newPrice)
{
return (new StockItemServant(newCode, newName, newPrice));
}
}
-----------------------------------------------------------------------------------------------------------
3. Create the server
import Stock.*;
import org.omg.CosNaming.*;
import org.omg.CosNaming.NamingContextPackage.*;
import org.omg.CORBA.*;
public class StockItemServer
{
public static void main(String[] args)
{
try
{
//Create and initialize the ORB…
ORB orb = ORB.init(args, null);
//Create a StockItemServant object…
StockItemServant stockServant =
new StockItemServant(“S0001”, “The Unforgiven”, “15.90” );
//Register the object with the ORB…
orb.connect(StockServant);
//Create a StockItemFactoryServant object…
StockItemFactoryServant factoryServant =
new StockItemFactoryServant();
//Register the object with the ORB…
orb.connect(factoryServant);
//Get a reference to the root naming context…
org.omg.CORBA.Object objectRef =
orb.resolve_initial_references(“NameService”);
//’Narrow’ (‘downcast’) the context reference…
NamingContext namingContext =
NamingContextHelper.narrow(objectRef);
//Create a NameComponent object for the StockItem interface
NameComponent nameComp =
new NameComponent(“Stock”, “”);
//Specify the path to the interface…
NameComponent[] stockPath = {nameComp};
//Bind the servant to the interface path…
namingContext.rebind(stockPath, stockServant);
//Create a NameComponent object for the StockFactory interface…
NameComponent factoryNameComp =
new NameComponent(“StockFactory”, “”);
//Specify the path to the interface…
NameComponent[] factoryPath = {factoryNameComp};
//Bind the servant to the interface path…
namingContext.rebind(factoryPath, factoryServant);
System.out.print(“\n Server running…”);
java.lang.Object syncObj = new java.lang.Object();
synchronized(syncObj)
{
syncObj.wait();
}
}
catch(Exception e)
{
System.out.println(“*** Server error! ***”);
e.printStackTrace();
}
}
}
class StockItemServant extends _StockItemImplBase
{
//Declare the initialize instance variable…
private String code = “”;
private String name = “ ”;
private double price = “”;
//Constructor…
public StockItemServer(String newcode, Sring newname, double newprice)
{
code = newCode;
name = newName;
price = newPrice;
}
//Must supply the following ‘get’ and ‘set’ methods…
//Accessor method(‘get’ method) for stock code…
public String code();
{
return code;
}
//Accessor method(‘get’ method) for stock name…
public String name();
{
return name;
}
//Accessor method(‘get’ method) for stock price…
public double price();
{
return price;
}
}
class StockItemFactoryServant
extends _StockItemFactoryImplBase
{
//Method to create a StockItemServant object and return a
//reference to this object (allowing clients to create
//StockItem objects on the servant)…
public StockItem CreateItemServant(newcode, newName, newPrice)
{
return (new StockItemServant(newCode, newName, newPrice));
}
}
------------------------------------------------------------------------------------------------------------
4. Create a client
import Stock.*;
import org.omg.CORBA.*;
import org.omg.CosNaming.*;
public class StockItemClient extends HttpServlet
{
public static void main(String[] args)
{
try
{
//Create and initialize the ORB…
ORB orb = ORB.init(args, null);
//Get a reference to the root naming context…
org.omg.CORBA.Object objectRef =
orb.resolve_initial_references(“NameService”);
//’Downcast’ the context reference…
NamingContext namingContext =
NamingContextHelper.narrow(objectRef);
//Create a NameComponent object for the StockItem interface
nameComponent nameComp =
new NameComponent(“Stock”, “”);
//Specify the path to the interface…
NameComponent[] stockPath = {nameComp};
//Get a reference to the interface (reusing existing reference)…
objectRef = namingContext.resolve(stockPath);
//’Downcast’ the reference…
Stockitem stockRef1 =
StockItemHelper.narrow(objectRef);
//now use this reference to call methods of the StockItem object…
System.out.println(
“\nStock code: “+ stockRef1.code());
System.out.println(
“\nStock name: “+ stockRef1.name());
System.out.println(
“\nStock price: RM “+ stockRef1.price());
//Create a NameComponent object for the Stockfactory interface…
NameComponent factoryNameComp =
new NameComponent(“StockFactory”, “ “);
//Specify the path to the interface…
NameComponent[] factoryPath = {factoryNameComp};
//Get a reference to the interface(reusing existing reference)…
objectRef = namingContext.resolve(factoryPath);
//’Downcast’ the reference…
StockItemFactory stockFactoryRef =
StockItemFactoryHelper.narrow(objectRef);
//Use factory reference to create a StockItem object
//on the server and return a reference to this
//StockItem (using method CreateItem within the
//StockItemFactory interface)…
StockItem stockRef2 =
stockFactoryref.createitem(“S0002”, “Biography of Dr.M”, “45.95”);
//Now use this reference to call methods of the new StockItem object…
System.out.println(
“\nStock code: “ + stockRef2.code());
System.out.println(
“\nStock name: “ + stockRef2.name());
System.out.println(
“\nStock price: “ + stockRef2.price());
}
}
}
-----------------------------------------------------------------------------------------------------------
request.html
<html>
<head>
<title>Servlet <->CORBA </title>
</head>
<body bgcolor="#ffffcc" text="#006666">
<center>
<h3>Servlet <==> CORBA Communication</h3>
</center>
<form action="/developer/technicalArticles/Servlets/corba/..\servlet\MathServlet"
method="POST">
<center>
Stock Code: <input type=text size=10 name="code">
<br>
Stock Name: <input type=text size=10 name="name">
<br>
Stock Price: RM <input type=text size=10
name="price">
</center>
</form>
</body>
-----------------------------------------------------------------------------------
Answer 2:
1. Create IDL file
//Stock.idl
module Stock {
readonly attribute string code;
attribute string name;
attribute double price;
};
};
------------------------------------------------------------------------------------------------------------
2. Implement the interfaces
class StockItemServant extends _StockItemImplBase
{
//Declare the initialize instance variable…
private String code = “”;
private String name = “ ”;
private double price = “”;
//Constructor…
public StockItemServer(String newcode, Sring newname, double newprice)
{
code = newCode;
name = newName;
price = newPrice;
}
//Must supply the following ‘get’ and ‘set’ methods…
//Accessor method(‘get’ method) for stock code…
public String code();
{
return code;
}
//Accessor method(‘get’ method) for stock name…
public String name();
{
return name;
}
//Accessor method(‘get’ method) for stock price…
public double price();
{
return price;
}
}
class StockItemFactoryServant
extends _StockItemFactoryImplBase
{
//Method to create a StockItemServant object and return a
//reference to this object (allowing clients to create
//StockItem objects on the servant)…
public StockItem CreateItemServant(newcode, newName, newPrice)
{
return (new StockItemServant(newCode, newName, newPrice));
}
}
-----------------------------------------------------------------------------------------------------------
3. Create the server
import Stock.*;
import org.omg.CosNaming.*;
import org.omg.CosNaming.NamingContextPackage.*;
import org.omg.CORBA.*;
public class StockItemServer
{
public static void main(String[] args)
{
try
{
//Create and initialize the ORB…
ORB orb = ORB.init(args, null);
//Create a StockItemServant object…
StockItemServant stockServant =
new StockItemServant(“S0001”, “The Unforgiven”, “15.90” );
//Register the object with the ORB…
orb.connect(StockServant);
//Create a StockItemFactoryServant object…
StockItemFactoryServant factoryServant =
new StockItemFactoryServant();
//Register the object with the ORB…
orb.connect(factoryServant);
//Get a reference to the root naming context…
org.omg.CORBA.Object objectRef =
orb.resolve_initial_references(“NameService”);
//’Narrow’ (‘downcast’) the context reference…
NamingContext namingContext =
NamingContextHelper.narrow(objectRef);
//Create a NameComponent object for the StockItem interface
NameComponent nameComp =
new NameComponent(“Stock”, “”);
//Specify the path to the interface…
NameComponent[] stockPath = {nameComp};
//Bind the servant to the interface path…
namingContext.rebind(stockPath, stockServant);
//Create a NameComponent object for the StockFactory interface…
NameComponent factoryNameComp =
new NameComponent(“StockFactory”, “”);
//Specify the path to the interface…
NameComponent[] factoryPath = {factoryNameComp};
//Bind the servant to the interface path…
namingContext.rebind(factoryPath, factoryServant);
System.out.print(“\n Server running…”);
java.lang.Object syncObj = new java.lang.Object();
synchronized(syncObj)
{
syncObj.wait();
}
}
catch(Exception e)
{
System.out.println(“*** Server error! ***”);
e.printStackTrace();
}
}
}
class StockItemServant extends _StockItemImplBase
{
//Declare the initialize instance variable…
private String code = “”;
private String name = “ ”;
private double price = “”;
//Constructor…
public StockItemServer(String newcode, Sring newname, double newprice)
{
code = newCode;
name = newName;
price = newPrice;
}
//Must supply the following ‘get’ and ‘set’ methods…
//Accessor method(‘get’ method) for stock code…
public String code();
{
return code;
}
//Accessor method(‘get’ method) for stock name…
public String name();
{
return name;
}
//Accessor method(‘get’ method) for stock price…
public double price();
{
return price;
}
}
class StockItemFactoryServant
extends _StockItemFactoryImplBase
{
//Method to create a StockItemServant object and return a
//reference to this object (allowing clients to create
//StockItem objects on the servant)…
public StockItem CreateItemServant(newcode, newName, newPrice)
{
return (new StockItemServant(newCode, newName, newPrice));
}
}
------------------------------------------------------------------------------------------------------------
4. Create a client
import Stock.*;
import org.omg.CORBA.*;
import org.omg.CosNaming.*;
public class StockItemClient extends HttpServlet
{
public static void main(String[] args)
{
try
{
//Create and initialize the ORB…
ORB orb = ORB.init(args, null);
//Get a reference to the root naming context…
org.omg.CORBA.Object objectRef =
orb.resolve_initial_references(“NameService”);
//’Downcast’ the context reference…
NamingContext namingContext =
NamingContextHelper.narrow(objectRef);
//Create a NameComponent object for the StockItem interface
nameComponent nameComp =
new NameComponent(“Stock”, “”);
//Specify the path to the interface…
NameComponent[] stockPath = {nameComp};
//Get a reference to the interface (reusing existing reference)…
objectRef = namingContext.resolve(stockPath);
//’Downcast’ the reference…
Stockitem stockRef1 =
StockItemHelper.narrow(objectRef);
//now use this reference to call methods of the StockItem object…
System.out.println(
“\nStock code: “+ stockRef1.code());
System.out.println(
“\nStock name: “+ stockRef1.name());
System.out.println(
“\nStock price: RM “+ stockRef1.price());
//Create a NameComponent object for the Stockfactory interface…
NameComponent factoryNameComp =
new NameComponent(“StockFactory”, “ “);
//Specify the path to the interface…
NameComponent[] factoryPath = {factoryNameComp};
//Get a reference to the interface(reusing existing reference)…
objectRef = namingContext.resolve(factoryPath);
//’Downcast’ the reference…
StockItemFactory stockFactoryRef =
StockItemFactoryHelper.narrow(objectRef);
//Use factory reference to create a StockItem object
//on the server and return a reference to this
//StockItem (using method CreateItem within the
//StockItemFactory interface)…
StockItem stockRef2 =
stockFactoryref.createitem(“S0002”, “Biography of Dr.M”, “45.95”);
//Now use this reference to call methods of the new StockItem object…
System.out.println(
“\nStock code: “ + stockRef2.code());
System.out.println(
“\nStock name: “ + stockRef2.name());
System.out.println(
“\nStock price: “ + stockRef2.price());
}
}
}
-----------------------------------------------------------------------------------
OUTPUT
