Chapter 3: Creating C++ Components and Clients

Creating the application

To create and run the sample application:

Verify your environment

Before running the tutorial, verify these environment settings:

For all platforms, the JAGUAR environment variable must be set to the location of your EAServer installation.
For Windows, the PATH environment variable must include the EAServer dll subdirectory.
For UNIX platforms, the EAServer lib directory must be added to the shared library search path variable listed in Table 3-1 for your platform. If running on Solaris, and you use the Solaris version 4.x compiler, the EAServer lib_sol4x directory must be in LD_LIBRARY_PATH.
Table 3-1: Shared library search path variables for UNIX platforms
Platform

Variable name
Solaris
LD_LIBRARY_PATH
HP-UX
SHLIB_PATH
AIX
LIBPATH
Linux
LD_LIBRARY_PATH

**Table 3-1: Shared library search path variables for UNIX platforms**
Platform	Variable name
Solaris	LD_LIBRARY_PATH
HP-UX	SHLIB_PATH
AIX	LIBPATH
Linux	LD_LIBRARY_PATH

Configuring the Windows environment

To configure the command line where you are running the tutorials, run these commands, substituting your EAServer installation location for eas-home:
```
set JAGUAR=eas-home
set PATH=%JAGUAR%\dll;%PATH%
```
You can also edit these variables in the System dialog for the Windows Control Panel, or create a batch file to configure the settings.

Configuring the UNIX environment for C shell

To configure the C shell session where you are running the tutorials, run these commands, substituting your EAServer installation location for eas-home, and the shared-library variable from Table 3-1 for LIB_PATH:
```
setenv JAGUAR eas-home
setenv LIB_PATH $JAGUAR/lib:$LIB_PATH
```
If running on Solaris, using a version 4.x CC compiler:
```
setenv JAGUAR eas-home
setenv LD_LIBRARY_PATH \
$JAGUAR/lib_sol4x:$LD_LIBRARY_PATH
```

Configuring the UNIX environment for Bourne shell

To configure the Bourne shell session where you are running the tutorials, run these commands, substituting your EAServer installation location for eas-home, and the shared-library variable from Table 3-1 for LIB_PATH:
```
JAGUAR=eas-home export JAGUAR
LIB_PATH=$JAGUAR/lib:$LIB_PATH export LIB_PATH
```
If running on Solaris, using a version 4.x CC compiler:
```
JAGUAR=eas-home export JAGUAR
LD_LIBRARY_PATH=$JAGUAR/lib_sol4x:$LD_LIBRARY_PATH export LD_LIBRARY_PATH
```

Start EAServer and EAServer Manager

Starting the server

If the server is not already running, follow the instructions under “Starting the server”.

Starting EAServer Manager

If EAServer Manager is not already running, start it as described in “Using EAServer Manager”.

Define a package, component, and method

This section shows you how to use EAServer Manager to create the package, component, and method for the sample application.

For complete information on configuring packages, components, and methods, see Chapter 5, “Defining Component Interfaces,” in the EAServer Programmer’s Guide.

Define a new package

In EAServer, a package is a unit of deployment for a group of components that perform related tasks. All components created in the EAServer tutorials are installed in the Tutorial package.

Before a component can be instantiated by clients, it must be installed in a package, and that package must be installed in the server. The steps below create the package and component within the predefined “Jaguar” server to satisfy these requirements.

Creating the Tutorial package if it does not exist

In EAServer Manager, expand the servers folder, then expand the Jaguar server icon.
Expand the Installed Packages folder. If the Tutorial package is displayed, skip to “Define and install a new component”.
Highlight the Installed Packages folder, and select File | Install Package.

In the Package wizard, select Create and Install a New Package.

For the package name, enter Tutorial.
Click Create New Package.

You see the Package Properties window.
Click OK.

Define and install a new component

You will define a new C++ component, CPPArithmetic.

Defining the component

Click on the Tutorial package.
Select File | New Component.
In the New Component wizard, select Define New Component.

For the component name, enter CPPArithmetic.
Click Finish.

You see the Component Properties window.

Select the General tab. Fill in the fields as follows:

Field	Value
Description	Tutorial C++ component
Codeset	Server’s Codeset (default)
Component Type	C++
DLL Name	`libCPPArithmetic` (no extension)
C++ Class	`CPPArithmeticImpl`
C++ Executable	(blank)
Use Platform Independent Naming	Unchecked

Leave the remaining fields at their default settings.
Click OK.

Define the multiply method

The component interface will have one method, multiply.

Defining the component interface

Expand the Tutorial package. Double-click the CPPArithmetic component to show the Roles and Interfaces folders beneath it.
Double-click the Interfaces folder, and highlight the Tutorial::CPPArithmetic interface. If you do not see this interface, install it as follows:
1. Highlight the Interfaces folder and select File | Add Interfaces ...
2. In the Install Interface dialog box, highlight Tutorial::CPPArithmetic in the Selected to Install table, then click Install.
3. Highlight the Tutorial::CPPArithmetic interface that is now displayed under the Interfaces folder.
With the Tutorial::CPPArithmetic interface highlighted, select File | New Method.
Assign the name multiply to the method.
Click Create New Method.

You see the Method Properties window.
In the Return field, select double as the method’s return type.
Beneath the empty parameter list, click Add to add a parameter. In the New Parameter dialog:
- For the parameter name, enter m1.
- For Mode, select in.
- For Type, select double.
Click OK to close the New Parameter dialog box.
Repeat steps 7 and 8 to add a second parameter named m2 with a Type of double.
Click OK to close the Method Properties dialog box.

Generate stubs, skeletons, and implementation templates

Once you have created the package, component, and methods, you can generate the stub and skeleton files for the component. The client executable uses the stubs to invoke the server-side component methods. The server uses the skeleton to invoke your component implementation class.

Generating the stubs and skeletons

Click on the Tutorial package and select the CPPArithmetic component.
Select File | Generate Stubs/Skeletons.
Deselect Generate Java Stubs.
Select Generate Stubs, then check C++ Stubs. Leave the C/C++ Code Base field at the default setting, which should be the full path to your EAServer include subdirectory.
Click Next to display the skeleton generation options, and select Generate Skeletons.
Under Skeletons, select Generate Skeletons on Client and leave the C/C++ Code Base field at the default setting, which should be the full path to your EAServer cpplib subdirectory.
Click Finish.

Write the server-side code

EAServer Manager has generated C++ implementation templates for the component methods. Here we will fill in the implementation template, then build a shared library or DLL file. Finally, we will verify that the shared library or DLL is in the EAServer cpplib subdirectory, where EAServer expects to find C and C++ component library files.

Writing the server-side code

Navigate to the cpplib directory under your EAServer installation, then navigate to the Tutorial/CPPArithmetic subdirectory. You should see the following files:
- CPPArithmeticImpl.hpp.new Template for the component header file. Defines the CPPArithmeticImpl class. No changes are required for the tutorial, other than renaming the file as discussed below.
- CPPArithmeticImpl.cpp.new Template for the component implementation. Contains the definition of the component methods. Changes you must make to this file are described below.
- Tutorial_CPPArithmetic.cpp Source for the skeleton. Do not modify the generated skeleton code.
- make.nt Microsoft nmake makefile. The nmake utility is included with the Microsoft Visual C++ installation.
- make.unix UNIX makefile, for all UNIX platforms.
Rename the implementation files to CPPArithmeticImpl.hpp and CPPArithmeticImpl.cpp. (In other words, remove the .new extension from both file names).

Open CPPArithmeticImpl.cpp in a text editor, then find the definition of the multiply method. Change the definition so that it matches the one below:

CORBA::Double CPPArithmeticImpl::multiply
    (CORBA::Double m1,
    CORBA::Double m2)
{
    CORBA::Double result;
    result = m1 * m2;
    return result;
}

Save your changes.

Building the component on Windows

Verify your setup as described in “Verify your environment”.
Rename make.nt to Makefile, then open Makefile in a text editor. Find the definition of the ODBCHOME macro:
```
ODBCHOME=d:\msdev
```
Change the ODBCHOME definition to match the directory where you have installed Microsoft Visual C++, for example:
```
ODBCHOME="D:\engapps\devStudio\VC98"
```
Save your changes.
Build the DLL by running nmake (no arguments are required).

You should see a new file called libCPPArithmetic.dll. Verify that the makefile has copied this file to the EAServer cpplib subdirectory. If nmake fails, verify that you have renamed the .cpp and .hpp implementation files with the expected file names, and that you have applied the correct edits to CPPArithmeticImpl.cpp and Makefile.

Building the component on UNIX platforms

Verify your setup as described in “Verify your environment”.
Rename make.unix to Makefile.
On Solaris, the make file is compatible with the Solaris CC compiler, version 6.x. If you use a version 4.x compiler, edit Makefile and change -L$JAGUAR/lib to -L$JAGUAR/lib_sol4x. You must use the compiler version that is compatible with your server. The default server binary requires libraries compatible with the 6.x compiler, but you can override this setting when starting the server. For more information, see “Starting the server” in the EAServer System Administration Guide.
Build the shared library by running make (no arguments are required).

You should see a new file called libCPPArithmetic.ext, where ext is the appropriate shared library extension for your platform. Verify that the makefile has copied this file to the EAServer cpplib subdirectory.

If make fails, verify the following:

You have renamed the .cpp and .hpp implementation files with the expected file names, and that you have applied the correct edits to CPPArithmeticImpl.cpp.
The compile and link settings in Makefile are appropriate for your installation. The settings are defined in the file cpplib/make.include.plat, where plat is the platform code returned by running uname -s on your system. If necessary, edit this file to match your system configuration.

Write the client-side code

Create the source file for the sample C++ client, arith.cpp. You can find a copy of arith.cpp in the html/docs/tutorial/cpp subdirectory of your EAServer installation. Here is the source for arith.cpp:

/*
** arith.cpp -- Example C++ client for the EAServer C++
**   tutorial.
**
**   This program connects to EAServer,
**   creates an instance of the Tutorial/CPPArithmetic 
**   component, and invokes the multiply method.
**
** Usage:
**    arith iiop://<host>:<port>
**
**    Where:
**
**       <host> is the host name or IP address of the server machine. 
**
**       <iiop-port> is the server's IIOP port (9000 in the
**         default configuration).
**
*/

#include <stdio.h>
#include <iostream.h>
#include <string.h>
#include <Jaguar.hpp>
#include <SessionManager.hpp>
#include <Tutorial.hpp>    // Stubs for interfaces in Tutorial IDL 
                           // module.

int main(int argc, char** argv)
{
    const char *usage = 
"Usage:\n\tarith iiop://<host>:<iiop-port>\n";
    const char *tutorial_help =
"Check Jaguar Manager and verify that the"
"Tutorial/CPPArithmetic component exists "
"and that it implements the "
"Tutorial::CPPArithmetic IDL interface.";

    const char *component_name = "Tutorial/CPPArithmetic";

    try {

        if (argc < 2) 
        {
          cout << usage;
          return -1;
        }

        char* manager_url = argv[1];

        cout << "**** Creating session\n";

        // Initialize the ORB
        CORBA::ORB_var orb = CORBA::ORB_init(argc, argv, 0);

       // Create a SessionManager::Manager instance
       
       CORBA::Object_var obj = 
           orb->string_to_object(manager_url);
       SessionManager::Manager_var manager = 
         SessionManager::Manager::_narrow(obj);
        if (CORBA::is_nil(manager)) 
        {
           cout << "Error: Null SessionManager::Manager instance. Exiting. "
                << usage ;
           return -1;
        }

        // Create an authenticated session for user Guest
        // using password GuestPassword

        SessionManager::Session_var session = 
          manager->createSession("Guest", "GuestPassword");
        if (CORBA::is_nil(session)) 
        {
          cout << "Error: Null session. Exiting. " << usage;
          return -1;
        }

        // Obtain a factory for component instances by 
        // resolving the component name

        cout << "**** Creating component instance for " 
             << component_name << "\n" ;

        obj = session->lookup(component_name);
        SessionManager::Factory_var arithFactory = 
        SessionManager::Factory::_narrow(obj);

        if (CORBA::is_nil(arithFactory)) 
        {
           cout << "ERROR: Null component factory for component " 
                 << component_name 
                 << tutorial_help ;
            return -1;
        }

       // Use the factory to create an instance.

        Tutorial::CPPArithmetic_var arith = 
           Tutorial::CPPArithmetic::_narrow(arithFactory->create());

        // Verify that we really have an instance.
        if (CORBA::is_nil(arith)) {
            cout << "ERROR: Null component instance. "
                 << tutorial_help ;
            return -1;
        }


        // Call the multiply method.

        cout << "**** Multiplying ...\n\n";
        CORBA::Double m1 = (CORBA::Double)3.1;
        CORBA::Double m2 = (CORBA::Double)2.5;
        CORBA::Double result = arith->multiply(m1, m2);

        cout << (double)m1 << " * " << (double)m2 
             << " = " << (double)result
             << "\n\n";

    }
    
    // Explicitly catch exceptions that can occur due to user error,
    // and print a generic error message for any other CORBA system 
    // exception.

    // Requested object (component) does not exist.
    catch ( CORBA::OBJECT_NOT_EXIST cone )
    {
        cout << "Error: CORBA OBJECT_NOT_EXIST exception. Check the "
             << "server log file for more information. Also verify "
             << "that the " << component_name 
             << " component has been created properly in "
             << "Jaguar Manager. " << tutorial_help ;
    }

    // Authentication or authorization failure.
    catch ( CORBA::NO_PERMISSION npe )
    {
        cout << "Error: CORBA:: NO_PERMISSION exception. Check whether "
             << "login authentication is enabled for your server and "
             << "whether the component has restricted access. If so "
             << "edit the source file to use a valid user name and "
             << "password.\n";
    }

    // Invalid object reference.
    catch ( CORBA::INV_OBJREF cio ) 
    {
        cout << "Error: CORBA INV_OBJREF exception.";
    }

    // Communication failure. Server could be down or URL's port value
    // could be wrong.
    catch ( CORBA::COMM_FAILURE ccf ) 
    {
        cout << "Error: CORBA COMM_FAILURE exception. Check that the "
             << "specified host and IIOP port number are "
             << "correct and that the server is running. "
             << usage;
    }

    // Anything else.
    catch ( CORBA::OBJ_ADAPTER ) 
    {
        cout << "Error: CORBA::OBJ_ADAPTER \n";
    }
    catch ( CORBA::SystemException cse ) 
    {
        cout << "Error: CORBA System Exception. Check that the server "
             << "hostname and IIOP port are specified correctly, and "
             << "check the server's error log for more information.\n"
             << usage; 
    }

    return 0;
}

Compile the client executable

Compiling the client on Windows

Verify your setup as described in “Verify your environment”.

Create a batch file with these commands and run it:

SETLOCAL
call %JAGUAR%\bin\setenv.bat
set INCLUDE=.;%JAGUAR%\include;%INCLUDE%;
set INCLUDE=%INCLUDE%;%JAGUAR_JDK13%\include;
set INCLUDE=%INCLUDE%;%JAGUAR_JDK13%\include\win32
set LIB=%JAGUAR%\lib;%LIB%
cl /W3 /nologo /DWIN32 /Gd /GX -c arith.cpp
set SYSLIBS=kernel32.lib advapi32.lib
link /MAP /out:arith.exe arith.obj libjcc.lib libjutils.lib %SYSLIBS%
ENDLOCAL

Compiling the client on UNIX

Verify your setup as described in “Verify your environment”.
Create a shell script containing the commands for your platform from Table 3-2, then run the shell script.

Change the script file permissions to allow execution, for example, assuming you have named the script compile.sh:

chmod 777 compile.sh

**Table 3-2: Client compilation commands for UNIX platforms**
Platform	Shell script
Solaris	This shell script works with the Solaris CC compiler, version 6.x: #!/bin/sh . $JAGUAR/bin/setenv.sh CC -DJAG_NO_NAMESPACE -z muldefs -I. -I$JAGUAR/include \ -I$JAGUAR_JDK13/include -I$JAGUAR_JDK13/include/solaris \ -L$JAGUAR/lib -ljcc -ljtml_r -ljtli_r -lunic -lnsl \ -ldl -lthread -lm -ljutils -o arith arith.cpp If you use the version 4.x compiler, change `-L$JAGUAR/lib` to `-L$JAGUAR/lib_sol4x`.
HP-UX	This shell script uses the HP-UX ANSI C++ (aCC) compiler: #!/bin/sh . $JAGUAR/bin/setenv.sh aCC -c +DA1.1 +DS2.0 +u4 -DNATIVE -D_HPUX -D_POSIX_C_SOURCE=199506L \ -D_HPUX_SOURCE -I $(JAGUAR_JDK13)/include -I $(JAGUAR_JDK13)/include/hp-ux \ -I $(JAGUAR_JDK12)/include -I $(JAGUAR_JDK12)/include/hp-ux -I. \ -I$JAGUAR/include -L$JAGUAR/lib -lpthread -ljcc -lnsl -ljtml_r \ -ljinsck_r -lunic -ljutils -o arith arith.cpp
HP Itanium	This shell script uses the HP C++ (aCC) compiler: #!/bin/sh . $JAGUAR/bin/setenv.sh aCC -g +DD32 -mt -I$(JAGUAR_JDK13)/include -I$(JAGUAR_JDK13)/include/hp-ux \ -I$(JAGUAR_JDK14)/include -I$(JAGUAR_JDK14)/include/hp-ux -I. \ -I$(JAGUAR)/include -L$(JAGUAR)/lib -lpthread -lunic -ljtml_r -ljinsck_r \ -ljcc -lnsl -ljlog -o arith arith.cpp
AIX	This shell script uses the IBM native compiler: #!/bin/sh . $JAGUAR/bin/setenv.sh xlC_r -g -c -DDEBUG -DJAG_NO_NAMESPACE -DAIX -D_AIX -qcpluscmt -qnoro \ -qmaxmem=-1 -qarch=com -qtbtable=full -I $(JAGUAR_JDK13)/include \ -I $(JAGUAR_JDK12)/include -I. -I$JAGUAR/include \ -brtl -L$JAGUAR/lib -ljcc.so -lunic -ljtml_r.so -ljinsck_r.so \ -lpthread -lnsl -ljutils -o arith arith.cpp
Linux	This shell script uses the g++ compiler: #!/bin/sh . $JAGUAR/bin/setenv.sh g++ -c -D_GNU_SOURCE=1 -DLINUX -D_LINUX -D_REENTRANT -fPIC \ -fwritable-strings -pipe -g -DDEBUG -I $(JAGUAR_JDK13)/include \ -I $(JAGUAR_JDK13)/include/linux -I $(JAGUAR_JDK12)/include \ -I $(JAGUAR_JDK12)/include/linux -I. -I$JAGUAR/include \ -L$JAGUAR/lib -lpthread -ljcc -lnsl -ljtml_r -ljinsck_r \ -l unic -ljutils -o arith arith.cpp

Run the client executable

If you have not refreshed or restarted the server since creating the CPPArithmetic component, do so now before running the client program. Make sure your environment is configured as described in “Verify your environment”.

Run the executable, specifying the server host name and IIOP port number on the command line as follows:

arith iiop://host:iiop-port

For example:

arith iiop://myhost:9000

If everything is working, arith prints the results from the invocation of the multiply method. If not, check the error text printed on the console where you ran the client, and check for error messages in the server log file.