In this module, we will explore the various programming languages available on the OpenVMS platform. OpenVMS supports a wide range of programming languages, each with its own strengths and use cases. Understanding these languages and their integration with OpenVMS will enable you to choose the right tool for your specific programming needs.

1. Overview of Supported Languages
2. Language-Specific Features and Integration
3. Development Tools and Environments
4. Compiling and Running Programs
5. Interfacing with OpenVMS System Services

OpenVMS supports several programming languages, including but not limited to:

• C
• Fortran
• COBOL
• Pascal
• BASIC
• Ada
• Java
• Python

Each language has its own compiler and runtime environment on OpenVMS, allowing for a diverse range of applications to be developed.

• Strengths: High performance, low-level system access, widely used.
• Integration: Direct access to OpenVMS system services through system calls and libraries.

• Strengths: Numerical and scientific computing, legacy code support.
• Integration: Optimized for high-performance computing tasks on OpenVMS.

• Strengths: Business applications, data processing.
• Integration: Extensive support for file handling and database access on OpenVMS.

• Strengths: Strong typing, structured programming.
• Integration: Suitable for educational purposes and structured application development.

• Strengths: Ease of use, rapid application development.
• Integration: Ideal for beginners and simple application development on OpenVMS.

• Strengths: Safety-critical applications, strong typing, concurrency.
• Integration: Used in systems where reliability and maintainability are critical.

• Strengths: Platform independence, object-oriented programming.
• Integration: Java Virtual Machine (JVM) available on OpenVMS for running Java applications.

• Strengths: Ease of use, extensive libraries, rapid development.
• Integration: Python interpreter available on OpenVMS, suitable for scripting and automation.

OpenVMS provides a range of development tools to support these programming languages:

• Compilers: Each language has its own compiler (e.g., CC for C, FORTRAN for Fortran, COBOL for COBOL).
• Editors: Text editors like EDT, EVE, and TPU are available for code editing.
• Debuggers: Tools like DEBUG and LAD (Language-Sensitive Debugger) help in debugging programs.
• Integrated Development Environments (IDEs): IDEs like Eclipse can be configured to work with OpenVMS.

1. Write the Program: Create a file named hello.c with the following content:

   #include <stdio.h>
   
   int main() {
       printf("Hello, OpenVMS!\n");
       return 0;
   }
   

2. Compile the Program: Use the C compiler to compile the program.

   $ CC hello.c
   

3. Link the Program: Link the object file to create an executable.

   $ LINK hello
   

4. Run the Program: Execute the compiled program.

   $ RUN hello
   

   Output:

   Hello, OpenVMS!
   

OpenVMS provides a rich set of system services that can be accessed from various programming languages. These services include:

• File Management: Create, read, write, and delete files.
• Process Management: Create and manage processes.
• Memory Management: Allocate and deallocate memory.
• Networking: Communicate over networks using TCP/IP or DECnet.

To use system services in C, include the necessary headers and make system calls. For example, to get the current date and time:

In this section, we have introduced the various programming languages supported on OpenVMS, their specific features, and how they integrate with the system. We also covered the development tools available and provided a practical example of compiling and running a C program. Understanding these basics will prepare you for more advanced topics in OpenVMS programming, including detailed language-specific tutorials and interfacing with system services.