Getting Started¶

This guide walks you through implementing USP. Everyone starts with the domain core (service catalog, availability, booking), then reads the section for their deployment mode.

Choose Your Deployment Mode¶

graph TD
    subgraph domainCore [Domain Core — Start Here]
        S1["1. Introduction"] --> S2["2. Core Concepts"]
        S2 --> S3["3. Service Catalog"]
        S3 --> S4["4. Availability"]
        S4 --> S5["5. Booking Lifecycle"]
    end

    subgraph discovery [Discovery]
        S6["6. Discovery Registry (Optional)"]
    end

    subgraph ucpPath [UCP-Native Mode]
        S7["7. UCP-Native Mode"]
    end

    subgraph standalonePath [Standalone Mode]
        S8["8. Standalone Mode"]
    end

    subgraph shared [Shared Infrastructure]
        S9["9. Transport Bindings"]
        S9 --> S10["10. Security"]
    end

    subgraph extensions [Extensions]
        S11["11. Extensions"]
    end

    S5 --> S6
    S5 --> S7
    S5 --> S8
    S6 -.-> S7
    S6 -.-> S8
    S7 --> S9
    S8 --> S9
    S10 --> S11

UCP-Native Implementation Stages¶

If your platform supports UCP, follow these steps:

1. Register capabilities. Declare dev.usp.services.catalog, dev.usp.services.availability, dev.usp.services.bookings, and optionally dev.usp.services.paid_bookings in your /.well-known/ucp profile.

2. Implement service catalog. Expose the service catalog API (list services, get service, feed). See Service Catalog.

3. Implement availability. Expose availability query and optional hold mechanism. See Availability.

4. Implement booking lifecycle. Expose create, get, update, confirm, cancel, and reschedule booking operations. See Booking.

5. If offering paid services: Add the paid_bookings extension to your UCP checkout schema and implement the checkout flow.

6. If offering free services only: No checkout integration needed.

7. Implement transport binding for your chosen transport (REST, MCP, A2A, or ESP). Skip Standalone-only transport infrastructure.

8. Implement USP-specific security requirements. Skip Standalone-only security infrastructure — UCP provides it.

9. Optional: Implement the waitlist extension.

10. Optional: Register in a discovery registry.

Standalone Implementation Stages¶

If your platform does not use UCP:

1. Create your business profile. Publish a /.well-known/usp profile declaring capabilities, transport endpoints, and optional checkout systems.

2. Implement capability negotiation. Support the USP-Agent header and server-selects negotiation model.

3. Implement service catalog. See Service Catalog.

4. Implement availability. See Availability.

5. Implement booking lifecycle. See Booking.

6. If offering paid services: Implement payment integration — choose the generic payment flow and/or the ACP booking extension.

7. If offering free services only: Skip payment integration entirely.

8. Implement transport binding for your chosen transport and transport infrastructure (TLS, CORS, rate limiting).

9. Implement security — both USP-specific requirements and standalone security infrastructure (OAuth 2.0, webhook signatures).

10. Optional: Implement the waitlist extension.

11. Optional: Register in a discovery registry.

Capabilities¶

USP defines three core capabilities and optional extensions:

Transport Bindings¶

Machine-Readable Artifacts¶

Cross-Cutting Concerns¶

USP references IETF standards directly: