Feeds

Reclaiming a different legacy

It isn't just COBOL you know...

Securing Web Applications Made Simple and Scalable

What is "legacy"? It's worth remembering that a lot of systems were written in RAD (Rapid Application Development) tools such as PowerBuilder and Visual Basic in the nineties and this is now often undocumented legacy in small companies (and some not-so-small ones) - just as COBOL systems are in large enterprises.

In fact, although I'm all in favour of RAD done properly (using a process such as DSDM, or JAD (Joint Application Design), some of this sort of "rapidly produced" legacy was produced with little process and less business input (often the person who can be spared to talk to IT is the person who can't do the business). So, it is often undocumented and possibly even dysfunctional in part. But it may still be in use, often in companies that have now made a strategic decision to run J2EE or .NET web services.

Shows a Legacy Decision Matrix.

Ian Diaper, principle consultant with Northdoor, says this stuff can often be reclaimed – after applying some sort of a legacy decision matrix to decide whether it will be worthwhile. Essentially, if legacy isn't offering value, retire it; if it is both useful and maintainable, keep it; if it is useful and unmaintainable, transform it (Northdoor's Matrix, in the illustration provided by Northdoor, is a little more sophisticated than this; there's a link to a bigger version of this here).

But beware of transforming legacy without a good business reason, just because new technologies are more fashionable – the pointy haired boss may not realise this, but most developers can turn their hand to any language, given a little training and encouragement.

For transformation, Diaper recommends technology from Canadian company Metex, a long-term partner of Northdoor. Northdoor, in fact, supplies transformation consultancy as much as the technology, and Metex can transform legacy written in Powerbuilder, Oracle Forms, RPG, Delphi, and Centura.

According to David Ballard (consultancy director, at Northdoor): "It isn't just a case of 'translating' legacy 4GL syntax to run under J2EE or .NET using conversion tools or compilers. These are totally different architectures and such literal translation will just deliver the old logic in a new language, bringing none of the benefits of the new architecture. Logic must be coded in a completely new structure. This coding involves an understanding of the business logic in the old application&."

Well, that's true of any legacy reclamation: the code tells you what the legacy does, but you need a domain expert (and, if you're lucky, the documentation) to tell you why it does it; and a technologist to make sure you get the best out of what you're moving to.

But with the sort of 4GL legacy we're talking about (and, to my mind, including Visual Basic makes for a fairly loose definition of 4GL), elucidating the business requirements may be an even worse problem. At least legacy COBOL developments followed some sort of recognised process; with Visual Basic, for example, the process may have been in the head of the coder. And, a system which made sense in the London Office where it was prototyped may have been rolled out worldwide – and may now be causing horrendous problems in, say, Shanghai. If you are to reclaim legacy effectively, you can't simply reproduce the status quo together with any problems it has.

Bridging the IT gap between rising business demands and ageing tools

More from The Register

next story
NO MORE ALL CAPS and other pleasures of Visual Studio 14
Unpicking a packed preview that breaks down ASP.NET
Cheer up, Nokia fans. It can start making mobes again in 18 months
The real winner of the Nokia sale is *drumroll* ... Nokia
Mozilla fixes CRITICAL security holes in Firefox, urges v31 upgrade
Misc memory hazards 'could be exploited' - and guess what, one's a Javascript vuln
Put down that Oracle database patch: It could cost $23,000 per CPU
On-by-default INMEMORY tech a boon for developers ... as long as they can afford it
Google shows off new Chrome OS look
Athena springs full-grown from Chromium project's head
Apple: We'll unleash OS X Yosemite beta on the MASSES on 24 July
Starting today, regular fanbois will be guinea pigs, it tells Reg
HIDDEN packet sniffer spy tech in MILLIONS of iPhones, iPads – expert
Don't panic though – Apple's backdoor is not wide open to all, guru tells us
prev story

Whitepapers

Designing a Defense for Mobile Applications
Learn about the various considerations for defending mobile applications - from the application architecture itself to the myriad testing technologies.
Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Top 8 considerations to enable and simplify mobility
In this whitepaper learn how to successfully add mobile capabilities simply and cost effectively.
Seven Steps to Software Security
Seven practical steps you can begin to take today to secure your applications and prevent the damages a successful cyber-attack can cause.
Boost IT visibility and business value
How building a great service catalog relieves pressure points and demonstrates the value of IT service management.