Ad server or sales agent: which source do I need?

Every storefront draws inventory from one or more inventory sources. The source family you pick is set by executionType, and it depends on what you already run. This page maps what you own to the right family, then explains all four.

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Decision table

Start from what you operate today.

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The four families

The authoritative definition of each family:

AGENT is an external AdCP-compatible sales agent the Merchandising Agent connects to; MANAGED_SALES_AGENT is an operator-owned ad server with Interchange-managed sales-agent plumbing behind it; LINKED_STOREFRONT is wholesale inventory discovered automatically from the ambient pool of LISTED, transacting storefronts (resolved at runtime, never persisted as a source row); MODULAR_SOURCE is a composed inventory source assembled from private modules such as avails, booking, trafficking, and reporting. Storefront-level ADAPTER dispatch is configured on the storefront, not as an inventory source.

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Ad server (MANAGED_SALES_AGENT)

Pick this when you own an ad server — Google Ad Manager, FreeWheel, or SpringServe — and want to sell its inventory through your storefront. Interchange manages the sales-agent plumbing in front of it: buyers transact against your storefront while the ad server reads its existing ad units, placements, and products. These sources carry a provisioningStatus and use the ad-server connection and lifecycle endpoints (connect, save config, test, launch, deactivate, reactivate), not the generic create flow. See Get ad-server connection and Replace ad-server config.

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External sales agent (AGENT)

Pick this when you already run — or want to connect — your own AdCP-compatible sales agent reachable at a URL. You register it with the source endpoint, supplying the endpoint URL, protocol (MCP or A2A), and auth. Your Merchandising Agent then calls that agent for discovery and media buys. This is the only family created and updated through the generic inventory-source create and update flow. See Create inventory source and Diagnose third-party sales agents.

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Linked storefront (LINKED_STOREFRONT)

Pick this when you want supply from other storefronts already transacting on the Interchange. Linked inventory is discovered automatically from the ambient pool of LISTED storefronts and resolved at runtime — there is no source row to create or manage. You participate by being LISTED; matching wholesale inventory surfaces to your storefront scoped by your own channel and geography.

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Modular (MODULAR_SOURCE)

Pick this when inventory and execution do not come from one compliant upstream agent. A modular source is composed from private modules — an avails feed, a booking ledger, trafficking, status sync, reporting import — and presents one buyer-facing surface. Use it when, for example, a publisher sends a periodic avails file, confirms bookings by hand, and uploads delivery reports after the campaign ends. See the Modular lifecycle guide.

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Still unsure?

• You operate an ad server and want to sell its inventory → ad server.
• You have an AdCP agent at a URL → external sales agent.
• You want inventory from the marketplace with nothing to connect → linked storefront.
• Your supply is stitched together from feeds and manual steps → modular.

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