Guide to CORBA University Sample Applications

The Basic Sample Application

This topic includes the following sections:

For an explanation of concepts associated with CORBA applications and a description of the development process for CORBA applications, see Getting Started with BEA Tuxedo CORBA Applications.

How the Basic Sample Application Works

The Basic sample application allows users to browse for available courses and get details on selected courses. Figure 3-1 illustrates how the Basic sample application works.

The Basic sample application demonstrates the following features:

The OMG IDL for the Basic Sample Application

The first step in creating client and server applications is to specify all of the CORBA interfaces and their methods using OMG IDL. The Basic sample application implements the following CORBA interfaces:

Listing 3-1 shows the univb.idl file that defines the CORBA interfaces in the Basic sample application. A copy of this file is included in the directory for the Basic sample application.

module UniversityB

{

   typedef unsigned long CourseNumber;
   typedef sequence<CourseNumber> CourseNumberList;

   struct CourseSynopsis
   {
        CourseNumber   course_number;
        string         title;
   };

   typedef sequence<CourseSynopsis> CourseSynopsisList;

   interface CourseSynopsisEnumerator
   {
        CourseSynopsisList get_next_n(
            in unsigned long number_to_get, 
            out unsigned long number_remaining
        );
         void destroy();
 };

   typedef unsigned short Days;
   const Days MONDAY    =  1;
   const Days TUESDAY   =  2;
   const Days WEDNESDAY =  4;
   const Days THURSDAY  =  8;
   const Days FRIDAY    = 16;
  
   struct ClassSchedule
   {
       Days           class_days; // bitmask of days
       unsigned short start_hour; // whole hours in military time
       unsigned short duration;   // minutes
   };

   struct CourseDetails
   {
       CourseNumber   course_number;
       double         cost;
       unsigned short number_of_credits;
       ClassSchedule  class_schedule; 
       unsigned short number_of_seats;
       string         title;
       string         professor;
       string         description;
   };

   typedef sequence<CourseDetails> CourseDetailsList;

   interface Registrar
   {
       CourseSynopsisList
       get_courses_synopsis(
          in string                    search_criteria,
          in unsigned long             number_to_get, // 0 = all
          out unsigned long            number_remaining,
          out CourseSynopsisEnumerator rest
       );
   CourseDetailsList get_courses_details(in CourseNumberList 
        courses);

   interface RegistrarFactory
   {
        Registrar find_registrar(
        );
   };
};

Generating the Client Stubs and the Skeletons

The interface specification defined in OMG IDL is used by the IDL compiler to generate client stubs for the client application and skeletons for the server application. The client stubs are used by the client application for all operation invocations. You use the skeleton, along with the code you write, to create the server application that implements the CORBA objects. For information about generating and using client stubs and skeletons, see Getting Started with BEA Tuxedo CORBA Applications.

During the development process, you would use the idl command to compile the OMG IDL file and produce client stubs and skeletons. This task has been automated in the makefile for the Basic sample application. For a description of the idl command, see the BEA Tuxedo Command Reference.

Writing the Client Application

The CORBA environment in BEA Tuxedo only supports CORBA C++ types of client applications.

During the development process, you would write client application code that does the following:

C++ versions of the client application code in the Basic sample application are provided. For information about writing client applications, see Getting Started with BEA Tuxedo CORBA Applications and Creating CORBA Client Applications.

Writing the Server Application

During the development process, you would write the following:

C++ code for the Server object and the method implementations in the University server application are provided.

During the development process, you use the genicf command to create an Implementation Configuration File (ICF). You then edit the ICF file to define activation and transaction policies for the Registrar, RegistrarFactory, and CourseSynopsisEnumerator objects. For the Basic sample application, the Registrar, RegistrarFactory, and CourseSynopsisEnumerator objects have an activation policy of process and a transaction policy of ignore. An ICF file for the Basic sample application is provided.

For information about writing server applications, see Creating CORBA Server Applications .

Configuring the Basic Sample Application

A key part of any CORBA application is the UBBCONFIG file. Although creating a UBBCONFIG file is the task of the administrator, it is important for programmers to understand that the file exists and how the file is used. When system administrators create a configuration file, they are describing the CORBA application using a set of parameters that the BEA Tuxedo software interprets to create a runnable application.

There are two forms of the configuration file:

For information about the UBBCONFIG file and the tmloadcf command, see Setting Up a BEA Tuxedo Application and the BEA Tuxedo Command Reference .

Building the Basic Sample Application

To build the Basic sample application, complete the following steps:

The following sections describe these steps.

Copying the Files for the Basic Sample Application into a Work Directory

The files for the Basic sample application are located in the following directories:

Windows

drive:\TUXDIR\samples\corba\university\basic

UNIX

/usr/TUXDIR/samples/corba/university/basic

In addition, you need to copy the utils directory into your work directory. The utils directory contains files that set up logging, tracing, and access to the University database.

Table 3-1 lists and describes the files you will use to create the Basic sample application.

Changing the Protection on the File for the Basic Sample Application

During the installation of the BEA Tuxedo software, the sample application files are marked read-only. Before you can edit the files or build the files in the Basic sample application, you need to change the protection of the files you copied into your work directory, as follows:

Windows

prompt>attrib -r drive:\workdirectory\*.*

UNIX

prompt>chmod u+rw /workdirectory/*.*

Setting the Environment Variables

Use the following command to set the environment variables used to build the client and server applications in the Basic sample application:

Windows

prompt>setenvb

UNIX

prompt>/bin/ksh

prompt>. ./setenvb.sh

Initializing the University Database

Use the following command to initialize the University database used with the Basic sample application:

Windows

prompt>nmake -f makefileb.nt initdb

UNIX

prompt>make -f makefileb.mk initdb

Loading the UBBCONFIG File

Use the following command to load the UBBCONFIG file:

Windows

prompt>tmloadcf -y ubb_b.nt

UNIX

prompt>tmloadcf -y ubb_b.mk

Compiling the Basic Sample Application

During the development process, you would use the buildobjclient and buildobjserver commands to build the client and server applications. However, for the Basic sample application, this step has been done for you.

The directory for the Basic sample application contains a makefile that builds the client and server sample applications.

Use the following commands to build the CORBA C++ client and server application in the Basic sample application:

Windows

prompt>nmake -f makefileb.nt

UNIX

prompt>make -f makefileb.mk

Running the Basic Sample Application

To run the Basic sample application, complete the following steps:

Starting the Server Application

Start the system and sample application server applications in the Basic sample application by entering the following command:

prompt>tmboot -y

This command starts the following server processes:

Before using another sample application, enter the following command to stop the system and sample application server processes:

prompt>tmshutdown

Starting the CORBA C++ Client Application

Start the CORBA C++ client application in the Basic sample application by entering the following command:

prompt>univb_client

Using the Client Applications in the Basic Sample Application

The following sections briefly explain how to use the client applications that are included in the Basic sample application.

The CORBA C++ Client Application

After starting the CORBA C++ client application, a menu with the following options appears:

<F>   Find courses

<A>   List all courses

<D>   Display course details

<E>   Exit

To find courses that match a particular curriculum subject, complete the following steps:

To list all the courses in the database, complete the following steps:

To display the details of a particular course, complete the following steps:

To exit the C++ CORBA client application, enter E at the Options prompt.