Decouple Mainframe and IBM i
Systems Safely, Innovate Instantly
OpenLegacy’s decoupling patterns build a controlled bridge between your mainframe and the cloud.
Modernization Planner designs how and where to decouple safely; Integration Studio generates the services
and connections that keep both sides in sync—so you modernize in accelerated, de-risked, phases with no
disruption to the business.
Why Decoupling Matters?
87% of businesses still rely on legacy systems, making changes risky. OpenLegacy Hub removes hidden
dependencies, replacing complex gateways and SQL with clear connections, enabling modernization while
keeping existing apps and processes running alongside new cloud-native services.”
The result is a modernization journey that is:
Accelerated
New services and components are usable immediately, connecting via stable contracts instead of fragile legacy code.
De-risked
Critical processes continue as workloads move in waves; if needed, rollback happens at the bridge, not the entire platform.
Agile
You can adjust priorities and iterate without overhauling the strategy. The decoupling bridge keeps old and new systems reliably connected.
Phased
You modernize domain by domain, pattern by pattern—starting where value is highest—while operating hybrid legacy + modern for as long as you need.
Decoupling isn’t a minor technical detail; it’s the modernization bridge that lets you treat transformation as a continuous, low-risk flow of changes instead of a one-time, high-risk event.
Learn why enterprises choose OpenLegacy?
What are Modernization Decoupling Patterns?
OpenLegacy Hub applies repeatable patterns to convert legacy dependencies into
governed interfaces. Modernization Planner suggests boundaries and patterns, while
Integration Studio generates the necessary services and connections.
A few of the most utilized decoupling patterns are:
Internal Decoupling
Breaks hidden in-program and cross-module calls into explicit service contracts, so individual components can be refactored, rehosted, or rewritten without breaking consumers.
External Decoupling
Wraps legacy gateways and channels with modern interfaces, so mobile apps, web portals, and partners remain stable while back-end logic moves to new platforms.
Data-Layer Decoupling
Extracts embedded SQL and direct table access into governed data services, so you can progressively introduce cloud-ready data stores, analytics, and AI without destabilizing core transactions
Where Modernization Decoupling Patterns
Fit in Your Modernization Journey
Decoupling patterns are woven into the OpenLegacy Hub flow. You’re not starting from a blank
whiteboard; the platform guides you from discovery to an executable plan to generate components.
Analyze & Visualize
The analyzer feature within Modernization Planner maps programs, gateways, and data dependencies for the planned phase
You see domains, hot spots, and candidate seams for decoupling across applications, channels, and data
Outcomes:
A shared picture of your legacy landscape
Planner Proposes Boundaries & Patterns
Based on dependencies, domains, and priorities, Planner suggests which boundaries to introduce and which patterns (internal, external, data) apply to each.
You review the plan, refine priorities, and approve the decoupling waves
Outcomes:
A priority and functional-driven plan instead of ad-hoc integrations.
Integration Studio Builds the Modernization Bridge
Integration Studio generates the APIs, reverse APIs, interceptors, and data connections, ensuring workload-movement tasks are coordinated across each wave
These contracts create a bridge between legacy and cloud for controlled, visible data exchange.
Outcomes:
A governed bridge providing safe connection of legacy and cloud without channel disruption
Coexist, Retire & Optimize
Legacy and modern components coexist across the bridge while you move domains in waves
As more traffic flows to modern implementations, you retire legacy modules and optimize the architecture using the same functional driven structure defined in the Planner.
Outcomes:
Modernization accelerated via many small, reversible steps instead of a single risky cutover.
Example Scenarios for
Decoupling Patterns
Launch new digital experiences fast
You need a new mobile app or portal, but customer and policy data live deep inside monolithic applications.
Result
Move faster on digital while OpenLegacy maintains the bridge back to the mainframe
Support refactoring and rehosting waves
You’re refactoring or rehosting parts of a large application, but everything is bound by brittle in-program calls
Result
Move workloads more quickly with generated clear, governed boundaries, not brittle point-to-point calls
Modernize the Data side for Analytics & AI
You want to power analytics platforms and AI models, but critical data is locked in DB2 / VSAM or tightly bound to code
Result
Decoupling the data layer lets analytics and AI progress without disrupting transactions or waiting for core replacement
Reduce the risk of a core system replacement
You need to exit off your mainframe or IBM i platform, but a single “big weekend cutover” feels impossible
Result
With a decoupling plan and connections, replacement becomes controlled go-lives with clear rollback options
Ready to Decouple Legacy
Safely and Move Faster?
OpenLegacy’s modernization decoupling patterns give you a proven way to untangle legacy complexity, maintain business continuity, and create a clear bridge to cloud, data, and AI initiatives—on your timeline, with your tools, and without big-bang risk
