---
last_verified: 2026-04-25
source: https://docs.oracle.com/en/solutions/implement-lbaas-error-page/index.html
diagram_asset: https://docs.oracle.com/en/solutions/implement-lbaas-error-page/img/lbaas-maintenance-page.png
pattern: cloud-native-lbaas-error-page
classification: single-region cloud-native operations workflow
---

lessons:
  - Oracle Architecture Center operational workflow diagrams can place regional managed services outside the VCN while still inside the OCI region boundary. Do not force Object Storage, Monitoring, Notifications, or DNS into a subnet unless the source diagram does.
  - Numbered flow badges are part of the official visual grammar for process-oriented reference architectures. Render them only when the spec provides `flow_order`.
  - The LBaaS custom error page reference uses a fixed-coordinate composition rather than a standard tiered top-to-bottom layout: users and Object Storage are left of the VCN, Monitoring and Notifications are below the VCN, and DNS sits at the lower-right edge of the VCN.
  - Native PowerPoint reconstruction needs icon aliases for `internet_gateway`, `functions`, `monitoring`, `notifications`, and `dns`; otherwise the renderer falls back to generic service cards.

layout_rules:
  absolute_layout:
    use_when:
      - Reconstructing an official Architecture Center diagram from a PNG/SVG reference.
      - The source diagram uses non-grid subnets, regional services outside VCN, or numbered workflow connectors.
    required_fields:
      - canvas
      - containers
      - services
      - connections
    validation:
      - Generate draw.io and native PPTX from the same coordinate model.
      - Render the coordinate model to PNG using `tools/oci_archcenter_eval.py`.
      - Compare against the official PNG and inspect deviations before accepting.

service_aliases:
  internet_gateway: internet_gateway
  igw: internet_gateway
  functions: oci_functions
  function: oci_functions
  monitoring: monitoring
  notifications: notifications
  notification: notifications
  dns: dns

benchmark_case:
  workspace: examples/eval-2026-04-25-lbaas-error-page
  drawio_spec: examples/eval-2026-04-25-lbaas-error-page/specs/lbaas-error-page-diagram-spec.yaml
  deck_spec: examples/eval-2026-04-25-lbaas-error-page/specs/lbaas-error-page-deck-spec.yaml