Mobile file management app with serial and parallel approval flows for a hydrocarbon engineering firm

Context

The client is a prominent India-based hydrocarbon engineering firm whose project documents — engineering drawings, technical specifications, management-of-change records, vendor data sheets — live in internal Microsoft SharePoint document libraries.

Approval routing for these documents is rarely simple. Engineering drawings move sequentially through a defined chain of reviewers. Compliance documents often need parallel sign-off from several stakeholders at once. Some flows are mixed: an outer serial chain with parallel approval steps embedded inside it.

The SharePoint web UI handled the storage and audit trail well, but the approval experience was desktop-bound and slow on mobile. Project managers and field engineers were the bottleneck — they were rarely at a desk.

Challenge

Two non-negotiable constraints shaped the brief:

1. SharePoint stays the system of record. No parallel database for documents, no mirrored library that drifts over time.
2. Approval logic must handle all three flow types — serial, parallel, and mixed — without separate screens or mode switches.

Plus the usual mobile constraints: large engineering drawings on patchy site networks, identity through Microsoft Entra ID, and a full audit trail that auditors can reconcile against SharePoint directly.

Approach

We built a native mobile application that talks directly to SharePoint through the Microsoft Graph API. The approval engine sits in a thin backend service:

• Flow definitions are declarative — each document type maps to a flow template that can compose serial and parallel steps to arbitrary depth.
• State machine tracks each in-flight approval. Reviewers see only what is actionable to them at the current step.
• File access uses Graph API delegated permissions, so file-level SharePoint security carries through to the mobile app with no separate permission model.
• Audit events are written back to a SharePoint custom list keyed to the document — auditors can verify against the source library without leaving SharePoint.

Mobile-side: progressive thumbnail rendering for large drawings, offline queue for approvals taken without connectivity, and biometric re-auth for the sign-off action itself.

Outcome

Field approval cycle time dropped from days to hours. Engineering deliverables that previously stalled waiting for a stakeholder to be at their desk now clear within a working day.

SharePoint remained the canonical store — no parallel silo, no data drift. The application has been rolled out across multiple project sites and continues to be extended with additional flow templates as new document categories come into scope.