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Technical Architecture

REV Spain — Technical Architecture

See the Diagrams page for the deployment diagram. See the Functional Overview for goals, context, and users.

1. Building Block View

REV Spain is a monolith. Main internal modules:

  • Intake module — claimant onboarding and document/data submission entry point
  • Extraction engine — parses ITA and RNT documents (fixed-structure official Spanish government PDFs) using direct PDF text extraction (no OCR, since layout is standardized)
  • Unified.to adapter — alternative ingestion path fetching employee/salary data directly from client HR/payroll systems
  • Project & employee allocation module — gathers project information and maps employees to projects
  • Eligibility rules engine — evaluates R&D tax credit eligibility criteria
  • Report generator — produces both financial and technical claim reports
  • Access control — role-based access for claimants, reviewers, and admins

2. Deployment View

Stack

  • Frontend: Vue.js 3 SPA
  • Backend: Node.js / Express API
  • Data & document storage: MongoDB, including GridFS for document storage (no separate object storage service)

Topology

  • VM 1 — runs the full application stack via Docker Compose (frontend, API, MongoDB)
  • VM 2 — reverse proxy handling the domain name and TLS termination, forwarding to VM 1

This is a single-server deployment: no horizontal scaling or failover across app instances currently exists.

3. Risks & Technical Debt

  • Single point of failure — the entire application stack (including the database) runs on one VM; no redundancy or failover.
  • No documented scaling path — current architecture sits in tension with quality goals like fast data gathering and claims centralization at higher volume.
  • Shared storage engine — MongoDB serves both transactional data and GridFS document storage; document I/O could contend with regular query load as usage grows.
  • External dependency — the Unified.to ingestion path introduces availability dependency on a third party for one of the two data-gathering flows.
  • PII handling — sensitive employee/salary data is processed directly by the core system in both ingestion paths; encryption, access control, and retention policies should be explicitly reviewed and documented.
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