Dr. Dobb's | Can CORBA Sidestep Open-Source Licensing? (Web Techniques, Apr 2001)

Can CORBA Sidestep Open-Source Licensing? (Web Techniques, Apr 2001)

The open-source movement has sparked an explosion of new software and code, all freely available to developers. Companies that were once locked into costly licenses can now access the source code for everything from compilers, editors, and scripting interpreters to packages like MySQL and Linux. This is great for businesses that would rather extend existing code than reinvent the wheel—but there's a catch. If you rerelease the original code, most open-source licenses (with the notable exception of BSD-style licenses) require that you also give away the code to any improvements you've made. And a number of open-source licenses state that you may not use the code in commercial software you plan to license restrictively on a per-copy basis.

January 01, 2002
URL:http://drdobbs.com/can-corba-sidestep-open-source-licensing/184413466

Web Techniques: Figure 1

Figure 1

Using CORBA wrappers to leverage open-source code.

/* TaxExpert.h */

/************************/
/* Open Source Software */
/************************/

class TaxExpert
{
  public:
    double getTax( double amount );
};

# Makefile.cpp

include stdmk_nt

EXE = 	CashRegister.exe TaxExpertServer.exe

all: $(EXE)

clean:
	del *.obj
	del *_c.cpp
	del *_s.cpp
	del *.hh
	del *.exe
	del *.ior

#
# "TaxExpert" specific make rules
#

taxes_c.cpp: taxes.idl
	$(ORBCC) -no_tie taxes.idl

taxes_s.cpp: taxes.idl
	$(ORBCC) -no_tie taxes.idl

CashRegister.exe: taxes_c.obj ClientBasic.obj CashRegister.obj
	$(LINK_EXE) /out:CashRegister.exe CashRegister.obj \
	    taxes_c.obj ClientBasic.obj $(LIBORB) $(STDCC_LIBS)

TaxExpertServer.exe: taxes_s.obj taxes_c.obj TaxExpertServer.obj\   
                                    ServerBasic.obj TaxExpert.obj
	$(LINK_EXE) /out:TaxExpertServer.exe TaxExpertServer.obj \
            ServerBasic.obj TaxExpert.obj \
	          taxes_s.obj taxes_c.obj $(LIBORB) $(STDCC_LIBS)

/* TaxExpert.cpp  */

/************************/
/* Open Source Software */
/************************/

# include <math.h>
# include <stdlib.h>

# include "TaxExpert.h"

double TaxExpert::getTax(double amount)
{
	return amount * .05;
}

// OrigCashRegister.cpp
/*****************************************************/
/**** RESTRICTED SOFTWARE - MAY NOT BE USED     ******/
/**** WITHOUT A LICENSE                         ******/
/*****************************************************/

# include <stdio.h>
# include <stdlib.h>
# include "TaxExpert.h"

void main(int ac, char **av)
{
  double amount = 100.0;
  double tax = 0.0;

  TaxExpert expert = new TaxExpert();

  if (ac > 1)
    amount = atof(av[1]);

  tax = expert->getTax(amount);

  printf("The tax on %f is %f\n", amount, tax);
}

// taxes.idl

module Taxes
{
  interface TaxExpert 
  {
    double getTax(in double amount);
  };
};

//CashRegister.cpp
/******************************************************/
/**** RESTRICTED SOFTWARE - MAY NOT BE USED      ******/
/**** WITHOUT A LICENSE                          ******/
/******************************************************/

# include "ClientBasic.h"
# include "taxes_c.hh"
# include "corba.h"

# include <stdio.h>
# include <stdlib.h>


void main(int ac, char** av)
{
  double amount = 100.0;
  double tax = 0.0;

  CORBA::Object_var object = getObject("tax.ior");
  Taxes::TaxExpert_var taxExpert = Taxes::TaxExpert::_narrow(object);

  if (ac > 1)
    amount = atof(av[1]);

  tax = (double) taxExpert->getTax( (CORBA::Double) amount);

  printf("The tax on %f is %f\n", amount, tax);
}

 /* ClienBasic.h  */
/******************************************************/
/**** RESTRICTED SOFTWARE - MAY NOT BE USED      ******/
/**** WITHOUT A LICENSE                          ******/
/******************************************************/
# include "corba.h"

CORBA::Object_var getObject(char *iorFile);

     /*  ClientBasic.cpp  */
# include "ClientBasic.h"
# include <fstream.h>


CORBA::Object_var
getObject(char *iorFile)
{
  static CORBA::ORB_var orb = 0;
  CORBA::Object_var object = 0;

  if (orb == 0)
    orb = CORBA::ORB_init();

  // Read object reference from file
  ifstream in(iorFile);
  const int MAXBUF = 1024;
  char ior[MAXBUF];
  in.getline(ior, MAXBUF);
  in.close();

  // convert the stringified IOR to an object reference
  object = orb->string_to_object(ior);

  return object;
}

/* TaxCorba.h  */

/************************/
/* Open Source Software */
/************************/

# include "taxes_s.hh"
# include "TaxExpert.h"

class TaxExpertImpl : public virtual POA_Taxes::TaxExpert,
                      public virtual PortableServer::RefCountServantBase
{
  public:
    TaxExpertImpl()
      { theTax = new TaxExpert(); }

    CORBA::Double getTax(CORBA::Double amount)
      { return (CORBA::Double) theTax->getTax( (double)amount); }

  private:
    TaxExpert* theTax;
};