RPG or IBM RPG is a high-level programming language. It is designed to write business applications, so most RPG development services are focused on business application development for OS/400 and IBMi. First introduced for IBM 1401 in the 1950s, RPG was the default programming technology of IBM’s mid-range server computers for a long time. RPG has evolved rapidly since its inception. It is still used in the AS/400 and iSeries server computer product line. The recent version of RPG is RPG IV, and it’s the main programming component on IBMi OS. RPG IV is also referred to as ILE RPG.
What is ILE and how does it relate to RPG?
ILE RPG and RPG IV are not the same. Hence, ILE and RPG IV development services are not the same too. The former is an implementation of the latter. This implementation is specifically done to make RPG compatible with the Integrated Language Environment (ILE). Amongst several compilers in the ILE compiler family, one compiler, ILE RPG, provides support for RPG code compilation.
ILE is a different methodology for developing programs on the IBM i OS. Building ILE was not straightforward, as it took significant architectural enhancements to the IBMi platform. ILE constitutes compilers for RPG, COBOL, C, Visual Age for C++, and CL. The compilers have official names – they are, namely, ILE RPG, ILE COBOL, ILE C, and ILE CL. It is essential to refer to them like this because RPG and ILE RPG are not the same.
What is ILE and why is it important for ILE RPG?
There has always been a debate on the benefits ILE has over the older OPM (Original Program Model) when it comes to RPG development services. Unlike OPM, ILE allows for easier testing and maintenance. Code components are smaller, which makes it manageable to test code. More number of exception handling options allows for more control. With ILE, RPG developers have access to the C runtime library and several other APIs. It is easier to write optimized RPG code with ILE.
How are OPM and ILE RPG conceptually different?
All RPG versions before ILE RPG IV used OPM. In OPM, a single source member was compiled to a single executable program. ILE has a different compilation mechanism, and its compilation is of two steps. Source members are converted into module objects by the compiler.
Modules are sub-programs of the more extensive program. Multiple modules can be bound together, and an executable program is created. This aspect enabled an RPG programmer to write modular code. This architecture ensures the independence of the source program from the main program. The source program is only used for module creation. One or more modules are bound to create an executable.
How can Smaller Code Components Help?
Smaller code components provide more modularity. In OPM, it was generally monolithic code that was written. Extensive programs were hard to maintain. Although an RPG developer could write modular programs with OPM, it was still challenging to maintain. In ILE, RPG programs can be modular and do only one specific business task, unlike an extensive program performing multiple tasks.
Modular code also helped in understanding the code architecture. It was easy to pinpoint bugs by RPG development services engineers. Importantly, it was easier to test, as the unit test case could focus only on validating specific business applications. RPG developers benefit immensely from the ILE support because they can make changes to only one small module. It is also convenient to divide tasks amongst a team by assigning modules to specific developers.
How ILE Gives RPG Developers More Control?
RPG developers could isolate their overrides with Activation Groups. They could also use commitment control and shared-opens to control a small portion of the overall codebase. Any file override can be aligned to the activation group so that applications cannot interfere with each other. Upon the closure of the Activation Group, all of the activation group’s files are closed as well.
How ILE gives RPG Developers Adequate Exception Handling Options?
OPM allowed RPG developers to handle exceptions with error indicators and inquiry messages. With ILE, developers can pass back the exception to the calling program. There is a provision to register and run a procedure when an exception occurs. There is also a backup option to write and run a process when the primary system crashes.
The facility to trace back exceptions to the caller has always interested many an RPG programmer. To explain this better, let’s take the following example:
- Process A calls Process B. Process B calls Process C. Process A produces an error indicator when making the call to Process B. Process C gets an exception – let’s assume a divide by zero.
- In ILE, process A’s error indicator is established. Process B and Process C end; these processes do not show any inquiry information.
- In OPM, process C is inquired about the exception. Process B is asked about the failed call to Process C. Process A’s error flag is set.
As can be noted, both approaches are acceptable, but in the case of OPM, there are multiple calls to inquire. Whereas in ILE, there are no inquiry calls. How this may matter to any expert RPG developer from an RPG development services firm may arise. OPM programs may not be efficient in large programs, with multiple exceptions based on various conditions. On the other hand, ILE programs perform better. This simple inquiry message optimization can increase ILE RPG program execution performance several notches.
What are Activation Groups in ILE?
Activation Groups are an essential feature of ILE. It helps RPG development services engineers to divide their jobs by application modules. Once applications are modularized, each module can be managed independently. When a service program or program is called and uses a particular activation group, the system automatically creates the activation group.
Activation groups are only for temporary executions. The execution ends once the job ends or the activation group is reclaimed, or the program ends. Also, files opened through the activation group are closed. Programs using static storage whilst executing release the storage and allocated storage are also released. Also, scoped overrides and commitment-control ends. All of this is very beneficial for any RPG programmer working on a complex application development project.
Why is RPG programming a niche skill, and how Integrative Systems can help?
The industry is faced with a shortage of good RPG programmer professionals. Many of the IBMi developers are either retiring or moving to other technologies. So trying to hire RPG programmers might not be a good idea. A better option would be to hire a custom development services firm such as Integrative Systems for RPG development services. Integrative Systems has a strong RPG developer network, including seasoned RPG programmers who have decades of experience.
Another strong case for using the services of Integrative Systems is the evolution of the codebase of AS/400 and System i server computers. RPG code could have undergone modernizations. From proprietary syntax to open source, from a rigid structure to ILE, and from RPG to free form RPG – there have been a lot of changes. Customers would have upgraded their hardware, and along with the upgrade would have required adapting RPG application code with the help of RPG development services.
The newer IBM Power Systems application programs could be cleaner, modular, and co-existing with open-source programs. This makes it highly critical to seek expert RPG development services for any RPG application development, migration, or testing activity. Integrative Systems has been providing iSeries Consulting, RPG development, COBOL application development, and a host of several other services for decades.
Integrative Systems RPG programmers have the skills and knowledge to write modern RPG applications that can integrate with current open-source programs. One of IBM’s strengths lies in its ability to provide application compatibility. That’s why it is essential to write RPG programs that can integrate with SQL, JAVA, CL, XML, C#, HTML, JSON, and PHP.
Integrative Systems offer RPG development services. The project team members are experts at refactoring the code and upgrading legacy RPG code into newer versions such as ILE RPG, RPG IV, or RPG Free Form. As technology changes, they adapt their skill-sets accordingly and understand the aesthetics of modern-day application development. They know how to create pseudo-code, document code, create modular code, create reusable libraries, and use best practices such as the latest design patterns.
Integrative Systems (www.integrativesystems.com) can provide expert RPG development services. We specialize in the development, customization, implementation, integration, and modernization of RPG application programs. Contact us – email@example.com for expert RPG application development, maintenance, deployment, and up-gradation services and support.