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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

Tutorial: Rayfin app editor

CSA Loom rayfin-app — a backed template that scaffolds the Rayfin Backend-as-a-Service shape with real Azure services: Azure Functions + Cosmos DB + a Static Web App, wired together and fully editable. No Microsoft Fabric required.

What it is

Rayfin is Microsoft's open-source Backend-as-a-Service for Fabric (Build 2026 preview). The CSA Loom equivalent is a BACKED template: picking it INSTANTIATES three real, editable Loom items —

  • a user-data-function item — the API tier on Azure Functions,
  • an azure-cosmos-account item — the data store on Cosmos DB, and
  • a slate-app item — the Static Web App web tier,

wired together so the web app calls the Functions route and the Functions item reads/writes the Cosmos store. Every scaffolded item is a runnable Loom item, not a stub. The original code-first Rayfin SDK/CLI path (TypeScript + @microsoft/rayfin-core decorators deployed with npx rayfin up) remains an opt-in alternative.

When to use it

  • You want a full app stack (web + API + store) scaffolded in one click on your own tenant's Azure services.
  • You're evaluating the Rayfin programming model without a Fabric workspace.

Step-by-step in Loom

  1. Pick workspace + name. Choose + New item → Rayfin app (Fabric apps), then the target Loom workspace and a name for the app stack.
  2. Instantiate the stack. Loom creates the user-data-function (Azure Functions API), azure-cosmos-account (Cosmos DB store), and slate-app (Static Web App) items, then wires the web app to the Functions route and the Functions item to the Cosmos store.
  3. Land in the web app. You open the slate-app web tier, already bound to the Functions + Cosmos backend. Add widgets and queries over the live API.
  4. Author the backend. Open the user-data-function item to author the API (Python/TypeScript) and the azure-cosmos-account item to manage containers — all real, editable Loom items.
  5. Run it on your tenant. The stack runs on your tenant's Azure Functions, Cosmos DB, and Static Web Apps under your identity/network/governance; any unprovisioned runtime surfaces each editor's honest infra-gate while the full UI still renders.

The Azure backend it rides on

  • API tier: Azure Functions (user-data-function item).
  • Data tier: Azure Cosmos DB (azure-cosmos-account item).
  • Web tier: Azure Static Web Apps (slate-app item).

No Fabric required

All three tiers are first-class Azure services on your tenant; no Fabric workspace, capacity, or OneLake is involved.

Learn more