Automating Legacy System Understanding with AI to Accelerate Modernization Readiness
| Client | Industry | Solution Provided | Technologies Used |
|---|---|---|---|
| Global Product Company | Software & HiTech | Legacy System Modernization, AI-Generated System Intelligence | Construct™: Chronicle, GPT-4o, Claude, DocuWriter.ai, n8n, Flowise |
The Need
The client relied on a business-critical legacy system written in RPG, but faced mounting challenges that impeded modernization:
- Core business logic was deeply embedded in outdated RPG code with no centralized documentation or clear functional ownership
- Engineering velocity was constrained by limited system visibility, making it difficult to onboard new developers or plan transformation efforts
- Fragmented, undocumented architecture increased delivery risk and made feature planning a guessing game
- Without structured system knowledge, modernization initiatives stalled under the weight of uncertainty
The Solution
To accelerate transformation, Gorilla Logic deployed *Construct™: Chronicle—an AI-powered workflow that converts legacy source code into actionable system intelligence.
Key components included:
- Code Understanding at Scale: Using GPT-4o and Claude, Construct™:Chronicle ingested raw RPG source code and extracted logic summaries, dependency mapping, and technical narration
- LLM-Readable Context Generation: Integrated DocuWriter.ai to translate RPG syntax into structured input that large language models could interpret effectively
- Workflow Orchestration: Automated prompt routing, model sequencing, and content refinement using n8n and Flowise, enabling generation of multiple documentation types
- Multi-Format Outputs: Delivered clean, consumable outputs including program summaries, visual system diagrams, and a modernization-aligned feature backlog
Results
Faster Ramp-Up: Significantly reduced onboarding time for engineers by replacing tribal knowledge with structured, AI-generated documentation
Improved Knowledge Transfer: Eliminated reliance on hard-to-reach SMEs by making hidden logic visible and understandable
Modernization-Ready Backlog: Delivered LLM-generated Jira epics and feature stories aligned with modernization goals—ready for engineering execution
*Gorilla Logic Construct™ is how we deliver faster—with less engineering lift and greater confidence.
It’s not a product. It’s our portfolio of delivery-tested workflows, powered by modular AI agents. Every workflow is proven in delivery, reusable by design, and capable of cutting engineering work by 30-80%.
Construct™: Chronicle is our system documentation accelerator—built to extract undocumented logic to reduce SME reliance and guide modernization.
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