Home > Articles > Software Development & Management

  • Print
  • + Share This
This chapter is from the book

1.11 -The Business Case for Legacy Architecture Transformation

Legacy architecture transformation describes the process of modifying the form, design, and/or function of one or more legacy applications and/or data structures. A legacy architecture transformation strategy defines a commonly agreed upon philosophy that an enterprise can use to reconcile legacy architecture limitations with high-priority, time-critical business requirements.

Many business executives believe that aging legacy architectures will eventually be replaced with new, strategic systems. It would seem logical, so the thinking goes, to simply buy new application systems just as one would buy a new computer. This line of thinking is not unusual for someone not fully apprised of the state of legacy architectures and how these architectures have become intertwined with an enterprise's business model.

Most executives have held the belief for more than two decades that these systems would be replaced. Attempts were made to replace systems on multiple occasions. Initially, 4GLs were going to lead the way. Then it was the CASE revolution. During the early 1990s, IT believed that client/server systems would replace legacy environments. Y2K brought a cold dose of reality. Rewrites were impractical and improbable.

This problem is compounded today because few people can articulate what these systems do. IT has lost many of the legacy skills that developed these systems. This loss of skill extends into the business units as well. Not only are the people who built these systems gone, the users who asked for them to be built in the first place are also gone. Knowledge reclamation of critical software assets is in itself a good risk management policy.

Frustrated with failed rewrite efforts, many executives turned to the "buy" as opposed to "build" mentality. Third-party ERP systems were brought in during the mid- to late 1990s. Some implementations succeeded in part, while others failed entirely. The problem was that the old systems could not be easily displaced, while legacy data created a huge conversion challenge for implementation teams. ERP systems have now joined the ranks of legacy architectures. Many are written using propriety languages, do not support diverse e-business requirements, and have typically ended up running alongside inhouse legacy systems.

Over the past two decades, organizations have spent billions of dollars in failed legacy system replacement efforts. Global Y2K preparation alone cost a half a trillion dollars, and all that did was fix a date problem. Imagine, for a minute, that an organization had unlimited funding for a legacy replacement effort and no delivery deadline—ludicrous concepts, by the way, in today's modern business climate. Such a replacement effort would still fail using traditional rewrite strategies, because the business rules and underlying data could not be replicated through traditional user/analyst re-specification techniques. Organizations no longer know what these systems do.

In spite of all the efforts to replace legacy systems over the years, these systems continue to function and have actually grown in size on an annual basis. Occasionally, a new system is developed to surround or interface with an existing system, but legacy systems are deactivated in only a small percentage of cases.

While politics tend to drive many strategic systems initiatives, including the deployment of a multi-million-dollar ERP application, executives, managers, and analysts should take an objective view of more pragmatic options. Exploring some of the motivations behind failed replacement projects is an important step in this process. Below are some of the rationalizations that have driven high-profile, legacy replacement project failures.

  • "The old system does not do what we need, so we must build a new system from scratch, which means that IT should not even look at the old system for ideas on how to build the new system."

  • "User requirements have changed, so we are going to just ask the users what the new system should do. They can re-specify it from scratch."

  • "A large, multinational consulting firm assures me that a total replacement is the only way to go. If things go wrong, they can take the heat for it."

  • "The old system uses old technology and we need to build a new system using new technology."

  • "The mainframe has to go—along with the systems that run on it. I want the mainframe gone by the end of next year."

  • "We need to buy a package and get these old systems out of here."

  • "The best approach is to just leave the old systems alone. We can wrap them with new technology to make them do what they need to do."

"New technology, such as Java, XML, and HTML, will allow us to rewrite everything in less time."

Politics aside, allowing the advent or promise of new technologies to drive a legacy replacement decision is not wise from a business perspective. Junior programmers are no more likely to succeed in a rewrite than their predecessors did in prior decades using other "new" technologies.

Conventional wisdom has dictated several evolving schools of thought during the past decade. During the 1990s, the from-scratch rewrite approach was displaced by the ERP package implementation approach. The package replacement approach has since been displaced by the EAI approach. Legacy system wrappers, for many of the reasons stated previously, provide only a stopgap measure. This brings executives back to the table to discuss alternative approaches.

If your enterprise's executive team can bring itself to the point where frank dialog replaces political posturing or the promise of technological miracles, here are some questions that you can ask as a first step in crafting a legacy architecture transformation strategy. Can legacy systems be replaced any time soon by rebuilding them? If this were possible, we would have done that already. Remember that these are the same legacy data and application architectures that businesses and governments spent up to half a trillion dollars just to make Y2K-compliant. They did not replace them then and will not replace the bulk of these systems any time soon—at least not using conventional, re-specification methods.

Will buying and implementing an ERP package help address the situation? This should be examined carefully because there are many hidden traps in this approach. An ERP system may not conform to your business requirements or may clash with legacy systems and data to the point where competitive advantage is lost—not gained. ERP implementations can also drag on for years, may succeed only in certain business units, and can cost up to 10 times the cost of the software itself.

Can IT use wrapping or middleware tools to access or trigger the data and transactions embedded within these systems in such a way as to make them more agile and adaptable to business requirements? This can be done, but in limited ways. Many Web-based front-end systems already trigger back-end mainframe transactions, but this approach is limited at best. There are many examples where online banking systems cannot update a bank balance in real time, where an order system could not effectively trigger a procurement process, or where other Web-based interfaces failed to effectively complete many of the capabilities they initially promised. Legacy architecture limitations prevent quick fixes and easy answers. A phased approach, however, could incorporate the best notions from each of the above options and be heavily augmented with a variety of legacy architecture analysis, reuse, and transformation techniques. Most legacy transformation solutions are hybrid strategies that incorporate buy, build, and reuse options over a period of time that provides interim value through phased delivery cycles.

The business case for incorporating legacy architecture transformation strategies is based on the process of elimination. If legacy architectures are preventing you from expanding into new markets, delivering new products and services, fulfilling customer requirements, streamlining supply and distribution chains, going global, or just staying competitive, legacy architecture transformation can help. ERP packages, new development, and EAI may all be a part of this strategy, but legacy transformation may be the missing component to make these other strategies work.

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020