Legacy system assessment model: To retire or not to retire?

Balancing modern software with legacy systems that come with a laundry list of limitations and headaches is a tricky challenge for CTOs and CIOs. In this article we will explore the following points:

• Determining whether or not the system should be considered legacy;
• Advantages and disadvantages of keeping legacy software;
• Assessing different types of systems’ attributes;
• Introducing a model for identifying the right solutions to legacy systems.

How to recognize a legacy system

To determine if the stakeholders will consider the system to be legacy or not, you can ask yourself the questions below (if it’s applicable (Yes) or not (No) to the system). Please, note that some of these are subjective and you might want to answer Maybe or Don’t know:

• Is the system business critical?
• Is the system old? Was the last update quite a long time ago?
• Has the system been changed to meet organizational needs?
• Is the system degrading as changes are made?
• Does maintenance costs increase as changes are made?
• Does the system use obsolete languages?
• Does the system have poor, if any, documentation?
• Does the system have inadequate data management?
• Does the system have limited support capability?
• Does the system lack the architecture to evolve to meet emerging requirements?

If you answered Yes to more than half of these questions, congratulations, you have a legacy system on your hands. What’s next?

Weighing legacy pros and cons

Before deciding whether or not you will modernize, transition away, or abandon certain legacy software altogether, you need to be aware of its advantages and disadvantages.

Benefits include:

• The modernizations costs often outweigh keeping the legacy system;
• Reliability and familiarity of the legacy tech;
• Older apps are usually fully integrated into the company’s operations and still perform effectively, making it a tried-and-true method for getting things done;
• Modernizing software may bring business operations to a standstill while sticking with legacy systems ensures seamless and uninterrupted processes.

Disadvantages are:

• Talent issues – searching for new skilled professionals to maintain and support outdated technology is becoming akin to hunting for unicorns;
• Nowadays, many tasks and business processes need automating, such as document automation, which legacy systems do not offer;
• Incompatible and outdated processes;
• Legacy systems cause compatibility issues;
• Legacy systems may not receive security patching updates, leaving them vulnerable to outside intrusions that disrupt the system’s performance.

Different CTOs of different companies may prioritize the cons over the pros and decide to keep the old tech or do the opposite and abandon them.

Legacy system assessment model

There are several models for evaluating software, each emphasizing different attributes. The Open University’s research team proposes a scheme derived from the existing models that combine business and technical factors with contemporary architecture attributes and organizational considerations to produce a more extensive, unified approach that recognises the real world complexity of legacy systems.

The model output can then be plotted on a decisional matrix that indicates a recommended solution.

So, what attributes do you need to assess and how to count up their values to place your system on the matrix?

Well, for each attribute, you should ask yourself if you would answer Yes or No in the assessment of the legacy system. Next, put a value from very low to very high on the attribute (from 1 to 5; don’t know is 0).

Business Attributes:

• Economic value: Market value, Profitability index, IRR;
• Data value: Percentage of mission critical archives, Percentage of application dependant archives;
• Utility: Business function coverage range, Actual usage frequency, Customer/user satisfaction metrics;
• Specialization: Percentage of highly specialized functions, Percentage of generic functions.

Technical Attributes:

• Maintainability: Lines of code, Function points, Control flow, Knots, Cyclomatic complexity, Dead code rate;
• Decomposability/architecture: Architecture modularity, Percentage of modules with separation of concerns, Extensibility, Interoperability, Architectural style, Consumption;
• Deterioration: Backlog increase, Defect rate increase, Response-time increase, Maintenance time per request increase;
• Obsolescence: System age, Operating system version, Hardware version, Technical support availability, Security, Legality, System evolution required for business goals.

Organizational attributes:

• Internal development & maintenance;
• Outsourced development & maintenance;
• Technical maturity;
• Commitment to training;
• Skill level of system support, Response to change;

To convert the business attributes and technical attributes into final values, Open Search um use the following equations:

The combined values can then be plotted on the decision matrix from above that indicates a recommended solution.

The legacy system assessment model is a comprehensive approach for evaluating the status of your software. Whether you choose to transition away, update, or keep them the way you are, AINSYS can become a helping hand for you. AINSYS integration framework syncs data between every tool and platform your IT  team employs in their work, helping you get an accurate picture of your software. By leveraging this model and AINSYS tools, CTOs can ensure that they are making the right decisions for their organization and keeping up with the ever-changing technology landscape.

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