Case study · Government Adjacent Enterprise
Enterprise application and integration modernisation during an ERP transition
- Client persona
- Government Adjacent Enterprise
- Focus areas
- Legacy system modernisation AustraliaEnterprise application integrationERP modernisationAPI integration services
Executive summary
An organisation moving to SAP S/4HANA carried years of bespoke integrations and file based interfaces between legacy applications. The team mapped dependencies, rationalised the application landscape and designed an API led integration approach that protected operational continuity while retiring interfaces that no longer earned their keep.
Representative experience delivered by the MMG Tech team within complex enterprise and public sector environments. Client details are withheld and outcomes are described without unverified metrics.
The challenge
Why it mattered
Over time, point to point integrations had been added to solve immediate problems. Many relied on scheduled flat file exchanges, undocumented transformations and knowledge held by a few people.
An ERP transition would break these dependencies. Without a clear picture of what connected to what, the organisation risked either rebuilding every legacy interface or missing one that a critical process depended on.
- Undocumented bespoke integrations
- File based interfaces with limited monitoring
- Unclear data ownership and mapping
- Operational risk during cut over
- Technical debt carried into the new platform
The solution and architecture
What was done and why
- 01
Dependency discovery
Every interface was inventoried with its source, target, frequency, data objects, business owner and failure impact. Business processes were traced end to end so each integration could be tied to a real operational need.
- 02
Application rationalisation
Applications were assessed against retain, replace, retire and consolidate options. Where S/4HANA standard capability covered a need, custom applications and their interfaces were marked for decommissioning.
- 03
Integration architecture
The target state favoured reusable APIs and event based patterns through a managed integration layer instead of new point to point links. File based exchange was retained only where a partner or system genuinely required it, with added monitoring and error handling.
- 04
Data mapping and requirements
Business requirements and field level data mappings were documented between legacy structures and S/4HANA objects, with data quality issues logged and assigned before migration rather than discovered during testing.
- 05
Transition planning
Cut over was sequenced in waves, with interim bridging interfaces where legacy and new systems needed to run in parallel. Each wave had entry criteria, rollback options and business sign off.
- 06
Testing and operational transition
Integration test scenarios were built from real process flows. Support teams received runbooks and monitoring for the new integration layer before go live.
Outcome and impact
What changed
- A complete, owned view of application and integration dependencies
- Fewer bespoke interfaces carried into the future state
- A reusable API led integration pattern for later change
- Lower cut over risk through staged transition planning
- A clearer technology roadmap for remaining legacy applications
Capabilities demonstrated