The Interoperability Architecture

5.1 Layer 1 — Systems of Record

Each Service/Agency maintains its own general-ledger system of record (GFEBS, Navy ERP, DEAMS, DAI), which is the authoritative source for that organization's financial statements. No single DoD-wide general ledger exists — this is the structural reason DoD's enterprise-wide audit is really a “consolidation of audits,” one per reporting entity.

5.2 Layer 2 — Feeder / Execution Systems

Logistics and execution-level systems (GCSS-Army, LMP, GCSS-MC, DLA EBS) generate the underlying obligations, receipts, and cost transactions and push them into the Layer 1 general ledger via SAP/Oracle native interfaces or DoD-standard middleware. Cross-cutting feeder systems used DoD-wide regardless of Service — the Defense Travel System (DTS), Wide Area Workflow (WAWF, now part of Procurement Integrated Enterprise Environment/PIEE), the Defense Civilian Pay System (DCPS), and Global Exchange (GEX) — push standardized transactions into whichever Layer 1 system a given organization uses.

5.3 Layer 3 — Enterprise Data / Analytics

CDAO's Advana platform is the department-wide analytics and reporting layer that ingests data from every Layer 1 system (and many Layer 2 systems) for cross-department visibility, audit support, and increasingly AI/ML use cases. The Army's 2023 real-time SAP SLT streaming-replication pipelines from GFEBS and GCSS-Army into Advana's MySQL/S3 environment (and the planned federation into an Advana SAP HANA data layer) illustrate the current-generation approach: rather than nightly batch ETL, source ERPs now stream changed data in near-real time, and CDAO has signaled intent to extend this pattern to “dozens of existing systems” beyond the Army.

5.4 Layer 4 — External / Treasury

All systems ultimately reconcile Fund Balance with Treasury (FBWT) against Treasury's Governmentwide Treasury Account Symbol Adjusted Trial Balance System (GTAS) and Central Accounting Reporting System (CARS) reporting, and increasingly against Treasury's G-Invoicing platform for intragovernmental transactions — identified in recent GAO work as DoD's designated long-term solution for intradepartmental buy/sell activity across these very systems.