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Sample Code for Example.idl
The JavaTM 2 SDK, Standard Edition, v1.3 includes a new version of the IDL-to-Java compiler, idlj. This compiler supports new CORBA-standard features required for RMI-IIOP. This document shows the code generated by the IDL-to-Java compiler in accordance with the CORBA 2.3 specification.
The followng file, Example.idl, is written in the OMG Interface Definition Language. OMG IDL is a purely declarative language designed for specifying programming-language-independent operational interfaces for distributed applications. OMG specifies a mapping from IDL to several different programming languages, including C, C++, Smalltalk, COBOL, Ada, and Java. When mapped, each statement in OMG IDL is translated to a corresponding statement in the programming language of choice.
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Example.idl
module Example {
interface Counter {
boolean increment (in long arg);
};
};
Generated Files
The idlj compiler uses the IDL-to-Java mapping to convert IDL interface definitions to corresponding Java interfaces, classes, and methods, which you can then use to implement your client and server code. The following files are generated when Example.idl is compiled with the IDL-to-Java compiler, using the following command:
idlj -fall Example.idl
Counter.java, the signature interface
The signature interface file, Counter.java extends
org.omg.portable.IDLEntity, org.omg.CORBA.Object, and the
operations interface, CounterOperations. The signature interface is used as the signature type in
method declarations when interfaces of the specified type are used in other
interfaces. From the client's point
of view, an object reference for a CORBA Counter object
implements this interface.
Note: The Stub implements the Counter interface, where it
generates code for each method to marshall the arguments,
invoke the method, and then unmarshall the arguments.
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Example/Counter.java
package Example;
/**
* Example/Counter.java
* Generated by the IDL-to-Java compiler (portable), version "3.0"
* from Example.idl
* Monday, November 6, 2000 6:01:53 PM PST
*/
public interface Counter extends CounterOperations,
org.omg.CORBA.Object,
org.omg.CORBA.portable.IDLEntity
{
} // interface Counter
CounterOperations.java, the operations interface
The Java operations interface, CounterOperations.java, is used in
the server-side mapping and as a mechanism for providing optimized calls for
co-located clients and server. The server developer provides implementation for
the methods indicated by the operations interface.
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Example/CounterOperations.java
package Example;
/**
* Example/CounterOperations.java
* Generated by the IDL-to-Java compiler (portable), version "3.0"
* from Example.idl
* Thursday, November 9, 2000 7:04:12 PM PST
*/
public interface CounterOperations
{
boolean increment (int arg);
} // interface CounterOperations
CounterHelper.java, the Helper class
The Java class CounterHelper defines auxiliary
methods, notably narrow(), which is the CORBA
counterpart of Java casting.
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Example/CounterHelper.java
package Example;
/**
* Example/CounterHelper.java
* Generated by the IDL-to-Java compiler (portable), version "3.0"
* from Example.idl
* Thursday, November 9, 2000 7:04:12 PM PST
*/
abstract public class CounterHelper
{
private static String _id = "IDL:Example/Counter:1.0";
public static void insert (org.omg.CORBA.Any a,
Example.Counter that)
{
org.omg.CORBA.portable.OutputStream out =
a.create_output_stream ();
a.type (type ());
write (out, that);
a.read_value (out.create_input_stream (), type ());
}
public static Example.Counter extract (org.omg.CORBA.Any a)
{
return read (a.create_input_stream ());
}
private static org.omg.CORBA.TypeCode __typeCode = null;
synchronized public static org.omg.CORBA.TypeCode type ()
{
if (__typeCode == null)
{
__typeCode = org.omg.CORBA.ORB.init
().create_interface_tc (Example.CounterHelper.id (),
"Counter");
}
return __typeCode;
}
public static String id ()
{
return _id;
}
public static Example.Counter read
(org.omg.CORBA.portable.InputStream istream)
{
return narrow (istream.read_Object (_CounterStub.class));
}
public static void write (org.omg.CORBA.portable.OutputStream
ostream, Example.Counter value)
{
ostream.write_Object ((org.omg.CORBA.Object) value);
}
public static Example.Counter narrow (org.omg.CORBA.Object
obj)
{
if (obj == null)
return null;
else if (obj instanceof Example.Counter)
return (Example.Counter)obj;
else if (!obj._is_a (id ()))
throw new org.omg.CORBA.BAD_PARAM ();
else
{
org.omg.CORBA.portable.Delegate delegate =
((org.omg.CORBA.portable.ObjectImpl)obj)._get_delegate
();
return new Example._CounterStub (delegate);
}
}
}
CounterHolder.java, the Holder class
The Java class called CounterHolder holds a public Counter member. Holders are required for CORBA operations that take out or inout arguments, which, unlike CORBA in arguments, don't map directly to Java's pass-by-value semantics.
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Example/CounterHolder.java
package Example;
/**
* Example/CounterHolder.java
* Generated by the IDL-to-Java compiler (portable), version "3.0"
* from Example.idl
* Thursday, November 9, 2000 7:04:11 PM PST
*/
public final class CounterHolder implements
org.omg.CORBA.portable.Streamable
{
public Example.Counter value = null;
public CounterHolder ()
{
}
public CounterHolder (Example.Counter initialValue)
{
value = initialValue;
}
public void _read (org.omg.CORBA.portable.InputStream i)
{
value = Example.CounterHelper.read (i);
}
public void _write (org.omg.CORBA.portable.OutputStream o)
{
Example.CounterHelper.write (o, value);
}
public org.omg.CORBA.TypeCode _type ()
{
return Example.CounterHelper.type ();
}
}
_CounterStub.java, the client stub
The Java class _CounterStub is the stub file for the client-side mapping.
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Example/_CounterStub.java
package Example;
/**
* Example/_CounterStub.java
* Generated by the IDL-to-Java compiler (portable), version "3.0"
* from Example.idl
* Thursday, November 9, 2000 7:04:12 PM PST
*/
public class _CounterStub extends
org.omg.CORBA.portable.ObjectImpl implements Example.Counter
{
// Constructors
// NOTE: If the default constructor is used, the
// object is useless until _set_delegate (...)
// is called.
public _CounterStub ()
{
super ();
}
public _CounterStub (org.omg.CORBA.portable.Delegate
delegate)
{
super ();
_set_delegate (delegate);
}
public boolean increment (int arg)
{
org.omg.CORBA.portable.InputStream _in = null;
try {
org.omg.CORBA.portable.OutputStream _out = _request
("increment", true);
_out.write_long (arg);
_in = _invoke (_out);
boolean __result = _in.read_boolean ();
return __result;
} catch (org.omg.CORBA.portable.ApplicationException _ex)
{
_in = _ex.getInputStream ();
String _id = _ex.getId ();
throw new org.omg.CORBA.MARSHAL (_id);
} catch (org.omg.CORBA.portable.RemarshalException _rm)
{
return increment (arg);
} finally {
_releaseReply (_in);
}
} // increment
// Type-specific CORBA::Object operations
private static String[] __ids = {
"IDL:Example/Counter:1.0"};
public String[] _ids ()
{
return (String[])__ids.clone ();
}
private void readObject (java.io.ObjectInputStream s)
{
try
{
String str = s.readUTF ();
org.omg.CORBA.Object obj = org.omg.CORBA.ORB.init
().string_to_object (str);
org.omg.CORBA.portable.Delegate delegate =
((org.omg.CORBA.portable.ObjectImpl)
obj)._get_delegate ();
_set_delegate (delegate);
} catch (java.io.IOException e) {}
}
private void writeObject (java.io.ObjectOutputStream s)
{
try
{
String str = org.omg.CORBA.ORB.init ().object_to_string
(this);
s.writeUTF (str);
} catch (java.io.IOException e) {}
}
} // class _CounterStub
_CounterImplBase.java, the server skeleton
The Java class _CounterImplBase is the skeleton file for the server-side mapping.
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Example/_CounterImplBase.java
package Example;
/**
* Example/_CounterImplBase.java
* Generated by the IDL-to-Java compiler (portable), version "3.0"
* from Example.idl
* Thursday, November 9, 2000 7:04:11 PM PST
*/
public abstract class _CounterImplBase extends
org.omg.CORBA.portable.ObjectImpl
implements Example.Counter,
org.omg.CORBA.portable.InvokeHandler
{
// Constructors
public _CounterImplBase ()
{
}
private static java.util.Hashtable _methods = new
java.util.Hashtable ();
static
{
_methods.put ("increment", new java.lang.Integer (0));
}
public org.omg.CORBA.portable.OutputStream _invoke (String
method, org.omg.CORBA.portable.InputStream in,
org.omg.CORBA.portable.ResponseHandler rh)
{
org.omg.CORBA.portable.OutputStream out = null;
java.lang.Integer __method =
(java.lang.Integer)_methods.get (method);
if (__method == null)
throw new org.omg.CORBA.BAD_OPERATION (0,
org.omg.CORBA.CompletionStatus.COMPLETED_MAYBE);
switch (__method.intValue ())
{
case 0: // Example/Counter/increment
{
int arg = in.read_long ();
boolean __result = false;
__result = this.increment (arg);
out = rh.createReply();
out.write_boolean (__result);
break;
}
default:
throw new org.omg.CORBA.BAD_OPERATION (0,
org.omg.CORBA.CompletionStatus.COMPLETED_MAYBE);
}
return out;
} // _invoke
// Type-specific CORBA::Object operations
private static String[] __ids = {
"IDL:Example/Counter:1.0"};
public String[] _ids ()
{
return __ids;
}
} // class _CounterImplBase
Completing the application
To complete the application, the developer must write the client and server code.
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Sun Microsystems, Inc.
All Rights Reserved.
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