Writing Hello.idl

• IDL for Hello World is very simple; its single interface has a single operation.
• Three steps which are involved here are:

  Step 1: Declaring the CORBA IDL Module

  A CORBA module is a namespace that acts as a container for related interfaces and declarations.
  
  
  1. Start the text editor and create a file named Hello.idl.
  2. In your file, enter the module statement:

     
     module HelloApp { 
     		    // Add subsequent lines of code here.
     };
     
     

  3. Save the file. When you run idltojava on the IDL, this statement will generate a package statement in the Java code.

  Step 2: Declaring the Interface

  Like Java interfaces, CORBA interfaces declare the API contract that an object has with other objects. Each interface statement in the IDL maps to a Java interface statement when mapped.

  In your Hello.idl file, enter the interface statement:

  
  
  module HelloApp {
      interface Hello  // Add
      {                // these
                       // four
      };               // lines.
  }; 
  
  

  When you compile the IDL, this statement will generate an interface statement in the Java code. Your client and server classes will implement the Hello interface in different ways.

  Step 3: Declaring the Operations

  CORBA operations are the behavior that servers promise to perform on behalf of clients that invoke them. Each operation statement in the IDL generates a corresponding method statement in the generated Java interface.

  In your Hello.idl file, enter the operation statement:

  
  module HelloApp {
      interface Hello
      {
          string sayHello();  // Add this line.
      };
  };
  
  

  Because our little Hello World application has only a single operation, Hello.idl is now complete.