Dreambox
Java modernization and migration without a big-bang rewrite
We upgrade, restructure and transform long-lived Java systems step by step, while they keep running.
Typical starting points
- An old Java or Spring version that blocks upgrades and security patches.
- A monolith where every change is slow and risky.
- Performance or scaling limits that the current design cannot get past.
- Knowledge locked in a few people and little test coverage.
How we approach it
- Understand first: read the code, runtime behaviour and data flows; write down what the system really does.
- Protect behaviour: characterisation tests around critical paths before changing them.
- Upgrade the platform: Java 8 / 11 / 17 to 21, Spring Boot 2 to 3, build and CI modernization.
- Restructure: monolith to modular, then to separate services only where justified; introduce messaging where coupling hurts.
- Migrate in slices: strangler pattern, feature flags and parallel runs so production keeps working.
Why we are good at it
We maintain a multi-module Java 21 codebase ourselves and have worked on long-lived trading platforms, where downtime is expensive and changes must be safe. Our approach is practical: smallest safe step, deployed, measured, then the next one.
Next steps
Start with a review, or bring in a team to execute the migration. For Spring specifics see Spring Boot development.
Frequently asked questions
Should we rewrite or modernize incrementally?
Almost always incrementally. Rewrites carry long periods without delivered value and a high risk of repeating old mistakes. We use strangler patterns, module boundaries and tests around existing behaviour.
How hard is a Spring Boot 2 to 3 upgrade?
It depends on dependency age and test coverage. The usual work is the javax to jakarta change, updated libraries, security configuration changes and Java 17 or 21 baselines. We estimate after scanning the codebase.
Can you split our monolith into services?
We can, if the problem warrants it. Often the first step is a modular monolith with clear boundaries, and services are split out only where scaling or ownership demands it.
Will the system stay in production during the work?
Yes. Incremental migration without disrupting operations is the point of the approach.
Can you help with documentation and knowledge transfer?
Yes. We document what we find and change, and hand over to your team.
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