Large-scale migrations · Java

Java migrations, end to end.

J2EE, EJB, Struts, JSP, WebSphere, WebLogic, legacy Spring. Parity proof, starting at 1M lines of code.

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Why this can't wait

Three forcing functions pushing Java teams off legacy stacks right now.

Oracle changed the math

Java 8 stopped being free for commercial use. You're paying Oracle's per-employee licensing, switching JDK vendors, or migrating off. Migration is the long-term answer.

Your framework upgrade is blocked

Spring Boot 3 needs Java 17+. Jakarta EE 9+ broke the javax namespace. Most modern libraries followed. You can't move the framework without moving the runtime first.

The upgrade chain doesn't end

Upgrade the JDK and you trigger upgrades to Spring, Hibernate, build plugins, test frameworks. Each one has its own breaking changes. Nobody knows where the chain ends until you start pulling.

How we do it

Three layers, because nothing else works at this scale

The hardest Java codebases resist the usual playbook. Millions of lines. Spring 3.x, Struts, EJBs, custom frameworks. Tightly coupled, lightly documented. Static analysis alone misses intent. AI alone hallucinates. Consultants alone don't scale. We run all three on every job.

Layer 01

Deterministic analysis

Our proprietary engine maps the structure of your Java codebase. Dependencies, entry points, data flows, dead code, EJB topology, JSP surface, Struts actions, JNDI bindings, app-server-specific APIs. Output you can trust before making changes.

Dependency map
com.acme.portalJ2EE 1.4
├─ BillingAction.javaStruts 1
│    → BillingFacadeBeanStateless EJB
│    → jdbc/LegacyDSJNDI
│    → jms/PaymentQueueWebLogic JMS
├─ ProfileAction.java
└─ ReportsAction.javadead code
4 EARs · 2,140 files · 87 cross-module refs
Layer 02

AI for scale

Anchored in static analysis, our AI agents apply verified migration patterns across thousands of files. Struts actions to Spring controllers, JSPs to Thymeleaf or React, EJBs to Spring Boot services. Each pattern validated once, then scaled.

Migration diff
BillingAction.java → BillingController.java
- public class BillingAction extends Action {
- public ActionForward execute(ActionMapping m,
- ActionForm f, HttpServletRequest req,
- HttpServletResponse res) throws Exception {
- BillingForm bf = (BillingForm) f;
- return m.findForward("success");
- }
- }
+ @RestController
+ public class BillingController {
+ @PostMapping("/billing")
+ public BillingResponse post(@RequestBody BillingRequest req) {
+ return billingService.process(req);
+ }
+ }
Pattern: Struts Action → @RestController · Applied 312x
Layer 03

SMEs and AI experts

Senior Java engineers validate the output, add the know-how that only lives in people's heads, and catch the edge cases auto-translators miss. No "AI-best-effort" shipped.

Review annotations
Senior Java SME
BillingFacadeBean · CMT boundary

Container-managed transaction spans three EJB calls. Spring @Transactional won't replicate the suspend/resume semantics. Rewriting as a single service method with explicit propagation rules and a parity test for partial-failure rollback.

Senior Java SME
PaymentQueue · WebLogic JMS

Vendor-specific message ordering guarantee. Not portable to a generic JMS broker. Replacing with Kafka partition key by account ID, with replay test against production message stream. Locked.

Engagement model

Your Java migration, in four scoped stages

Four stages. Fixed price per stage. Commit one step at a time, with validation evidence at every one.

01

Assessment

Snapshot of your Java stack and modernization fit. JDK version inventory, app-server footprint, framework audit (Struts, EJB, JSF, legacy Spring), third-party library audit. Scoped plan, risks, and success criteria.

What you receive
  • Stack snapshot and inventory
  • Scoped plan
  • Risk register
  • Locked success criteria
02

Specification

Extract the business logic, critical flows, and system behavior teams and agents need to migrate code safely. Documented, queryable, with parity test specs locked.

What you receive
  • Architecture and dependency maps
  • Extracted business logic
  • Documented critical flows
  • Parity test specifications
03

Modernization

Migrate the code to your target Java stack. Refactor services where the original structure won't survive the move off the app server. Visible progress throughout.

What you receive
  • Migrated code on target Java stack
  • Refactored services where needed
  • API and integration code
  • Parity validation evidence
04

Enablement

Keep evolving your Java system independently. Parity test suite, playbooks, training, and knowledge base, handed off to your team.

What you receive
  • Parity test suite
  • Migration playbooks
  • Team training
  • Queryable knowledge base

Each stage builds on the last. Fixed price, with validation evidence at every step.

What you get

A workspace, not a stack of files

Every deliverable lives in one place. Yours to keep, queryable by your tools.

Delivered change

  • Migrated code on target Java stack
  • Refactored services where needed
  • API and integration code
  • Container-ready where applicable

System understanding

  • Architecture and dependency maps
  • Dead-code analysis
  • Extracted business logic
  • Critical flow documentation
  • Queryable by MCP

Enablement assets

  • Parity test suite
  • Migration playbooks
  • Team training
  • Queryable knowledge base

Move Java forward. With proof.

Get in touch with our team. We'll talk through your codebase, your target stack, and the right path off legacy Java.

Get in touch