Remote Lead Java Developer/Solution Architect (15-week contract) in Oldham

gravity9 is seeking a Technical Lead / Solution Architect to lead the design and build of a secure metadata catalogue platform for a UK public sector client. The platform will serve as a centralised index for discovering, governing, and controlling access to data distributed across multiple independent domains — enabling authorised parties to locate and retrieve data without the catalogue itself holding or having visibility of the underlying data. This is a greenfield build requiring strong architectural judgment, hands-on delivery capability, and the ability to work within a multi-vendor environment where the catalogue integrates with separate data storage and encryption services provided by other technology partners.

Duration: 15 weeks

Commitment: Half-time for the first 4 weeks (design phase); full-time for the remaining 11 weeks (build and integration)

Working model: Mostly remote with periodic onsite attendance

Security clearance: BPSS (Baseline Personnel Security Standard) required

Residency: UK resident required

Technical Scope: The contractor will be responsible for leading the design and delivery of the API layer and application logic. A dedicated database consulting engineer will handle MongoDB cluster configuration, schema design, indexing, and performance tuning — the contractor will collaborate closely with them but will own the application-layer delivery.

Architecture & Design (Weeks 1–4, half-time):

• Design the Attribute-Based Access Control (ABAC) model, including policy attributes (clearance level, nationality, group/role, context), enforcement points, and decision logic
• Design the RESTful API architecture, including endpoint structure, request/response contracts, and error handling patterns
• Map out query patterns, access flows, and integration touchpoints with external systems (data storage and encryption services provided by partner organisations)
• Collaborate with the database consulting engineer on schema design, search strategy, and encryption approach to ensure the API layer aligns with the underlying data model
• Contribute to Infrastructure as Code design for deployment (Terraform or similar)

Build & Implementation (Weeks 5–15, full-time):

• Build a RESTful API layer in Java implementing full catalogue functionality:
• CRUD operations for metadata records
• Advanced search capability leveraging Atlas Search
• ABAC enforcement on all API operations, ensuring search results and data retrieval are filtered by the requestor’s access attributes
• Secure storage and retrieval of encrypted key material (shard keys) via CS-FLE
• Implement unit tests to validate functional correctness
• Build automated data load and stress testing harnesses for the combined API and cluster deployment
• Perform integration testing against external partner systems (or appropriate stand-ins) to validate end-to-end data creation and retrieval flows
• Produce API documentation and integration guides for consuming systems
• Support knowledge transfer and training for client teams