Strategy & Transformation
Legacy System Modernization
Choosing and executing the right approach for a specific legacy core system, such as a mainframe, AS/400, Oracle Forms, VB6 or PowerBuilder application, while keeping the business running throughout.
Capability overview
What legacy system modernization involves
Legacy core systems often run critical operations reliably but are expensive to change, dependent on retiring specialists and difficult to integrate with modern channels. Big-bang replacements of such systems have a poor track record, so the modernisation approach has to match the system's condition and the business's tolerance for risk.
Options range from encapsulating the legacy system with APIs, through automated code conversion and re-platforming, to incremental replacement using the strangler fig pattern, where new services gradually take over functions until the old system can be switched off. Business rules buried in code are extracted and documented before anything changes.
What is included
Modernisation approaches
Code and rule analysis
Legacy code analysed to document business rules, data structures, batch jobs and interfaces, often for the first time in years.
API encapsulation
Legacy functions exposed through modern APIs so new channels can use them without touching the core.
Automated conversion
Tool-assisted conversion of languages such as COBOL, RPG or VB6 to Java or .NET, followed by manual refinement and testing.
Incremental replacement
Functions rebuilt one domain at a time, with routing that shifts traffic from legacy to new components.
Data migration
Historical data converted from legacy formats with reconciliation that proves nothing was lost or altered.
How we work
How we deliver legacy system modernization
System assessment
Code size, quality, documentation, integrations, data and support situation assessed.
Approach selection
Options compared for cost, risk, timeline and business disruption, with a recommended path.
Knowledge capture
Business rules and operational knowledge recorded with the experts who maintain the system.
Incremental delivery
Modernised components delivered in releases, each tested against legacy behaviour.
Decommissioning
Legacy system retired once all functions and data have moved and audit requirements are met.
Related capabilities
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How technology decisions are made, funded, delivered and controlled: governance forums, decision rights, IT operating model design, service management practices and alignment with frameworks such as COBIT and ITIL 4.
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Independent assessment of a company's technology before an investment, acquisition or partnership, covering product architecture, code quality, security, scalability, team, costs and risks that affect valuation.
Platform & Vendor Evaluation
Structured selection of software platforms and technology vendors, from requirements and shortlisting to scripted demonstrations, proof of concept, reference checks, total cost analysis and contract negotiation support.
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Questions & answers
Questions about Legacy System Modernization
Cannot find what you need? Our team responds to technical and commercial questions within one business day.
Ask a questionSometimes, when the system supports standard functions such as finance or HR. For systems embodying unique business rules, packaged replacement can require heavy customisation, and incremental modernisation may carry less risk.
By running the same inputs through old and new systems and comparing outputs automatically, including batch results and edge cases drawn from production history.
Knowledge capture becomes the first priority, combining interviews, code analysis and documentation so the organisation is not dependent on individuals during modernisation.
Encapsulation projects can take a few months. Full modernisation of a large core system usually runs one to three years, delivered incrementally so value arrives throughout.
Next step
Discuss legacy system modernization with Acmez
Share what you need to change, build, integrate or support. We will map the practical next step.