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CSA Loom — the Microsoft Fabric experience for Azure tenants where Fabric isn't yet available: lakehouses, warehouses, notebooks, semantic models, Activator rules, Data Agents, across Commercial, GCC, GCC-High, and DoD IL5

Data Activator parity (Reflex)

What Fabric does

Reflex (Data Activator) is a declarative rules engine over streaming + tabular events. Built on top of Eventhouse (KQL/ADX) for the query work + per-object state tracking for andStays / noPresence semantics. Per Microsoft engineering blogs (see research/03-fabric- only-internals.md §3), Reflex is not its own stream-processing runtime — it's a thin layer that schedules KQL queries against Eventhouse on intervals and maintains object state.

Entity model: Data sources → Events (filters / projections) → Objects (stateful entities keyed by splitColumn) → Attributes (computed properties) → Rules → Actions.

Rule primitives: increasesAbove, decreasesBelow, is above, is below, changesTo, andStays(duration), noPresenceOfData(seconds), everyNthTime(n, seconds).

Action surface: Teams, Email, Power Automate, Pipeline run, Notebook run, Spark job, Dataflow Gen2 refresh, User Data Function call.

End-to-end latency: 5-30 s.

CSA Loom parity design — apps/fiab-activator-engine

Full design in ADR fiab-0005. Summary:

Component Implementation
Query engine Azure Data Explorer (same Kusto engine Fabric Eventhouse uses)
Rule evaluator NRules (.NET production Rete rules engine)
Per-object state Azure Cache for Redis Premium (TTL'd keys)
Rule scheduler Cron orchestrator reading from Cosmos DB definitions
Action dispatcher Azure Functions with output bindings

All 8 Fabric Reflex primitives implemented. Latency target: 5-30 s end-to-end (matches Fabric).

Rule definition

JSON schema documented in apps/fiab-activator-engine/schemas/. Authored via Loom Console "Activator" pane (visual designer with KQL backing store) or directly in JSON for Git-based authoring.

Example (CPU high sustained):

{
  "id": "rule-cpu-high-andstays",
  "workspaceId": "ws-001",
  "name": "VM CPU sustained high",
  "dataSource": {
    "type": "adx-kql",
    "cluster": "adx-loom-eastus2",
    "database": "telemetry",
    "query": "VmMetrics | where TimestampUtc > ago(15m) | summarize avg(CpuPercent) by VmId, bin(TimestampUtc, 1m)",
    "splitColumn": "VmId",
    "cadenceMinutes": 1
  },
  "rules": [
    {
      "name": "Sustained CPU > 85% for 5 min",
      "expression": {
        "operator": "andStays",
        "left": {
          "operator": "isAbove",
          "attribute": "avg_CpuPercent",
          "threshold": 85
        },
        "durationMinutes": 5
      },
      "actions": [
        {
          "type": "teams-message",
          "channel": "#ops-alerts",
          "template": "VM {VmId} CPU is at {avg_CpuPercent}% for >5 min."
        },
        {
          "type": "databricks-job",
          "workspace": "dbx-ws-001",
          "jobId": "12345"
        }
      ]
    }
  ],
  "enabled": true
}

Action surface

Action type Binding
Teams message Graph API webhook
Email Azure Communication Services
Power Automate flow HTTP webhook
Logic App HTTP webhook
Databricks Job Databricks Jobs API
ADF Pipeline ADF REST
User Data Function Function call
Generic webhook HTTPS POST

Per-boundary behavior

Boundary ADX NRules / Redis / Functions
Commercial ✅ ✅ Container Apps
GCC ✅ ✅ Container Apps
GCC-High / IL4 ✅ ✅ AKS workload (Container Apps not at IL4+)
IL5 (v1.1) ✅ ✅ AKS workload

Honest gaps

  • Per-object state in Redis is functionally equivalent but Fabric's internal state store may have stricter exactly-once guarantees (Microsoft hasn't published these — flagged in research/03-fabric-only-internals.md §3 as thin info). Loom's semantics documented openly.
  • Visual rule designer is functional in v1 but won't match Fabric's drag-drop UX polish; v1.1 invests in UX parity.
  • Cron-based 1-min minimum cadence — Fabric's internal scheduler may run more often. For sub-second latency, use Azure Stream Analytics directly (out of scope).

Forward migration

Rules export to JSON via apps/fiab-activator-engine/export → Reflex definition import via Fabric REST API. State doesn't migrate (by design — rules re-arm in Fabric).