Enterprise Platform Engineering
Replace the old system one function at a time
Brihat Infotech moves businesses off ageing software without a weekend cutover. New modules take over one function at a time, and the old system keeps running everything else.
Start with a map
An architect, a QA lead and engineers study the system you have: what it does, what calls it, which reports depend on it and which records only it holds. The result is a dependency map. It shows what can move first and what must wait.
One approach per system, not one for the estate
Different systems need different treatment. For each one we pick from 7 approaches:
- Rehost
the same software on new servers.
- Replatform
the same software on a newer database or operating system.
- Refactor
tidy the code without changing what it does.
- Rearchitect
change the structure, keep the function.
- Rebuild
write it again to the same requirements.
- Replace
retire it for a package or a new custom system.
- Encapsulate
leave it alone and put a modern interface in front.
How the switch happens
- 01A new module takes one function. This is the strangler pattern, named for the vine that grows around a tree.
- 02Behaviour tests record what the old system does. The new module must pass the same tests.
- 03Both systems run side by side. Records move across with checksums, so totals on each side can be compared line by line.
- 04Interfaces stay. Other systems keep calling the address they know while the logic behind it changes.
- 05The old part is switched off on evidence. The parallel-run record shows nothing still depends on it.
What each switch-over leaves behind
- The dependency map
- The strangler plan: the order in which functions move
- Behaviour tests for each function that moves
- Parallel-run evidence for each switch-off
The work is incremental and has no fixed end date, because the order depends on what you find in the map. How we engage shows how to stop after any phase and keep what has been built.
Why a switch-off needs evidence
A system that has run for a decade does things nobody wrote down: a monthly export, a report finance still uses, a rule inside a stored procedure. The parallel run exposes them. While both systems run, the checksum comparison and the behaviour tests show every place where the new module differs from the old.
When a function has run in parallel without a difference, you have a record that the old part can go. Until then, nothing is turned off.
Common starting points
- Tally to a custom ERP: keep Tally for statutory books and GST.
- SAP ECC modernisation: convert to S/4HANA or build around it.
- A legacy hospital system to a patient platform: unify the patient record first.
More in Enterprise Platform Engineering
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The first call is 45 minutes with an architect, usually the founder. It is free, and we will sign an NDA first if you ask.