New RPG Open Access Standard Depends On XML

May 14, 2012 Dan Burger

A group of RPG heavyweights, including IBM, have come together in support of the first standard pertaining to RPG Open Access. But to understand RPG Open Access, start with the importance of RPG interfacing with other technologies. That’s not all that common. RPG has a reputation for its proprietary chains. Mistakenly this stops with the topic of green screens and graphical user interfaces. In reality, it is about the separation of the user interface from the business logic.

This newly created standard, which was announced May 8, attempts to get below the surface. It is targeted at extending the traditional display files, known as DDS, to an open format, and the idea is to create a framework for future development using RPG Open Access. Central to this is the use of XML, an open markup language, which in this case represents the proprietary DDS in the communication process.

Discussions about the Open Access Metadata Open Standard started more than a year ago. Through the community effort, it gathered momentum fairly fast. In short, the standard is a common protocol for future cross-platform development. As additional RPG Open Access interfaces are designed by software vendors and the open source community, there was concern that users might be constrained from combining the newly created handlers as a means of increasing functionality. That’s the theory anyway. And the hope is that this will result in cross-solution compatibility–another way of saying “no vendor lock-in.”

Handler With Care

The term “handler” refers to a program that allows RPG to communicate (via the DDS I/O buffer of RPG) with resources and devices that in the past have been on the other side of the DDS wall. Open Access (open communication), as defined in this standard, requires a trip beyond the display files that are integral to user interfaces and includes physical files and printer files as well. Certain instances require this larger scope and that answers the question about why the standard was necessary.

Unlike the limited support for resources and devices provided by RPG special files, RPG OA makes use of the I/O model to access devices that are not directly supported by RPG. Falling into the not directly supported category are items such as browsers, mobile devices, Web services, external databases, spreadsheets, and XML files. For RPG developers, the idea of accessing theses resources and devices using native RPG file specifications and I/O operations in their applications is very interesting and often confounding.

Consortium Rules

A consortium of RPG Open Access advocates was formed to shepherd the standard through an evolutionary process prior to the announcement, which arrived at the COMMON 2012 Annual Meeting and Exposition. IBM has supported and participated in the developer consortium.

Members of the consortium from IBM include Alison Butterill, IBM i product manager; Steve Will, IBM i chief architect; and Tim Rowe, business architect for application development for IBM i. Other members include RPG experts such as Jon Paris, Susan Gantner, Paul Tuohy, Scott Klement, Aaron Bartell, Brian May, Duncan Kenzie, Brendan Kay, and Vern Hamberg. A total of 26 members made the list, including Pascal Polverini, the author of the standard.

RPG Evolution

RPG enhancements have been built in to each release of the IBM i operating system since it was introduced as OS/400 in 1988 and later rebranded as i5/OS and now IBM i. Although the operating system is widely associated with the green-screen interface–which to the IT universe outside of the IBM i community dooms to legacy status–RPG has evolved to a modern, modular language, for those who have evolved with it. RPG developers with current skills and systems running on IBM i 6.1 and 7.1 can make use of RPG Open Access, which in IBM terminology is known by the product name Rational Open Access: RPG Edition. That product was first introduced in 2010 as a separately priced item, but eventually–after much frustration–became a piece of IBM i 7., with backward compatibility to i 6.1 via PTF. It provides the runtime enablement for the I/O handlers.

Among the IBM i software vendors, looksoftware has been the most vocal in its support of the Open Access Metadata Open Standard. Its development of an RPG Open Access-based handler adheres to the XML-based technique described in the standard. Polverini, the author of the standard and a strong proponent of XML, is an application modernization specialist in Italy. His company is also a reseller of looksoftware products.

The 5250 data stream limits access to metadata and stands in the way of controlling the appearance (the display) of RPG code, Polverini explained to me during an interview at COMMON. “With Open Access I can control the code and the description and the properties of elements that cannot be described by the DDS. I can do this with XML.”

However, if looksoftware is the only company using XML, this will not be a standard, he said.

Profound Logic, which has led the way in developing and marketing a handler that gets to the metadata level of DDS and separates the presentation layer from the business logic, has a different methodology. Instead of using XML as the vehicle that describes the DDS, Profound uses JSON and JavaScript.

Alex Roytman, CEO at Profound Logic, says that in general he supports the idea of a standard, but that Profound designed its RPG OA handler with JSON and JavaScript because it works better than XML in browsers and particularly with HTML5, which he is expecting to soon be the dominant Web and mobile application development technology.

Although JavaScript and JSON are limited to browsers, Roytman says browsers are the focus for Profound. Attention to printer files, physical files, database access, and other reasons for creating RPG OA handlers may be in Profound’s future planning, and if that happens, the company would look at XML-based options. As he sees it, there are no interoperability issues that divide Profound’s product with existing or future products based on XML.

“We chose the right technology for the right purpose,” he steadfastly says.

There are additional vendors with products based on RPG Open Access technology. ASNA claims some early customer success and Rocket Software is on the record as being “100 percent committed” to RPG Open Access.

And then there’s the open source community, which is expected to make some moves with RPG Open Access. All of this development work will make for some interesting debates and some good articles in the future.

For the time being, you can take a closer look at the ongoing circumstances at the wiki page devoted to the standard, which can be viewed here.

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