The new platform runs in front. DB2 keeps the record behind it.
Cloud-native group administration — the modernization the legacy pattern never produced, and the
template for every coexistence move that follows. This dossier is the coexistence story: what replaced
the old experience, how the new foundation runs alongside the old one, and what this lane still owes.
Client liveIBM CDC deployingDB2 authoritative
Platform
React front end and modern service layer over a target PostgreSQL foundation, while DB2 remains authoritative and coexistence evidence is being completed.
Pattern value
Guided workflows and reusable components define the GroupLink modernization pattern.
Discipline
Coexistence over big-bang: the legacy source stays in service while the modern foundation earns its way forward on evidence.
From legacy pattern to platform
The old screen taught the rules. The new product changes the work.
The goal is not to preserve the old screen pattern. The old experience tells us which operational jobs,
validation rules, and service states matter. The modern experience organizes those into a cleaner,
role-aware, auditable GroupLink Portal.
Prior state
Legacy CSR portal pattern
CSR LEGACY PHP PORTAL
GROUP ID 004829 | ELIG | BILL | CLAIM | NOTE | TASK | EXIT
Target-state visual for leadership discussion. Production captures can replace this visual after UX
approval, privacy review, and release readiness.
Both panels are illustrative mockups lifted from the working record; figures shown inside them are
sample workspace values, not reported results. The legacy screen teaches the business rules; the modern
product changes the work pattern — guided workflows, reusable services, and audit trails on every action.
The coexistence architecture
Two systems, one discipline: parity first.
This is not only a front-end refresh. The React front end carries the guided experience; a middleware
and API layer holds the reusable domain services, validation logic, authorization checks, audit events,
and integration contracts; and a PostgreSQL foundation lets new backend components mature without
forcing immediate production cutover risk.
DB2 and the existing systems are not diminished in this picture — they stay in production service
while parity, validation, reconciliation, and operational readiness are proven on the modern side.
Bidirectional IBM CDC deployment is underway while DB2 remains the authoritative system of record — parity first, cutover only on evidence.
Figure 01 — The coexistence architecture. IBM CDC keeps PostgreSQL and DB2 aligned in both
directions while DB2 remains the authoritative system of record; sovereignty flips are proposed
domain by domain and gated on parity evidence, not on calendar.
What this lane owes
Coexistence is a discipline, not a destination.
A live client in front does not close the lane. The remaining work is the disciplined part: hardening
the bridge, accumulating parity evidence, and engineering out what still depends on the mainframe.
Now CDC bridge deployment and coexistence hardening.
Next Domain-by-domain data sovereignty flips as parity evidence accumulates.
Owes The remaining mainframe dependencies targeted for engineering out — under the
proposed exit doctrine on the Journey track.
Boundary held openly: the mainframe exit is a proposed, evidence-gated doctrine — sequenced on
evidence, not on calendar. No cutover is stated here as a certainty; every sovereignty flip is gated on
dual-run parity evidence, and DB2 remains the authoritative system of record until that evidence exists.
Keep reading the record
Where this dossier connects.
GroupLink sits in the portfolio as Lane 02, while its coexistence and evidence-gated cutover doctrine
remains part of the Journey track.