Legacy application modernization
We write tests first, change code in small slices, and keep the old system running until the new one has earned the traffic.
The short answer
Legacy application modernization updates old systems so they run on supported platforms and can be changed safely. Ace8 targets enterprise Java estates: app servers, old Java and Spring versions, and tangled monoliths. We write tests first, change code in small slices with AI-assisted tools, and have senior engineers verify each slice before it ships.
Diagnosis
Age is not the test. A twelve-year-old application with good tests and a current runtime is not legacy. These are the signs that matter.
The cost of doing nothing
Waiting rarely looks expensive in any one year. The cost shows up in four places.
Licence and support fees recur. The jump between versions grows, because libraries drop old Java versions each year and current Spring versions need Java 17 or later. Security exposure accumulates. And every AI project that needs a current runtime, clean APIs and code you can test starts with a delay.
If an upgrade has to wait, you can stay on old versions safely while you plan. OSSeva provides extended support for older Java versions and open-source components. That buys time. It does not replace the plan.
Options
Rehost, replatform, refactor, re-architect, replace. Each fits a different application. The full comparison is on the application modernization services page. Here is how we narrow the choice for legacy Java.
Risk
Characterization tests record what the old code does today, including its quirks.
Callers talk to the interface, not to the implementation behind it.
AI-assisted tools make the repetitive edits. Tests and an engineer check the result.
Traffic shifts in steps. Each step has a rollback agreed in advance.
After the new one has carried real load.
Getting started
The first deliverable is the fixed-price assessment. It contains:
Platforms
After go-live
AceMQ supports the new stack 24/7. The run plan is written before cutover. See supported after migration.
Proof
American National moved from IBM MQ to RabbitMQ while the code that depended on the old broker was refactored. The cutover was phased, with no big-bang switch.
It is updating old systems so they run on supported platforms and can be changed safely. For Java that usually means a current runtime, a supported framework version, an open application server and automated tests.
Modernize unless the assessment shows the design itself is the problem. A rewrite resets all the learning embedded in the old code and carries the highest delivery risk.
Yes. We change one capability at a time behind a stable interface, with tests first and a rollback for every step.
OSSeva provides extended support for older Java versions while you plan. It is a way to buy time safely.
With the fixed-price assessment. You get the inventory, the risk score and a phased roadmap, and you decide whether to continue.
A fixed-price assessment gives you the inventory, the risk score and a phased plan. Scope and cost are fixed before the migration starts.
Book a Fixed-Price AssessmentGet in touch
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