> For the complete documentation index, see [llms.txt](https://hub.bsvblockchain.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hub.bsvblockchain.org/brc/overlays/0180.md). # Overlay Service Discovery at an Internet Domain David Case () ## Abstract A domain declares the overlay services it hosts in a `metanet.overlays` object in its `/manifest.json`, mapping service names to the base URL that serves them. ## Motivation Application URLs name domains, and a domain's overlay is routinely hosted somewhere other than its website. Without a declaration a client is left guessing at conventions such as an `api.` prefix. [BRC-68](/brc/peer-to-peer/0068.md) established `/manifest.json` as where a domain publishes details about itself, and [BRC-73](/brc/wallet/0073.md) and [BRC-169](/brc/peer-to-peer/0169.md) added their own objects there; this adds one for overlay services. [BRC-88](/brc/overlays/0088.md) answers a different question. SHIP tells a client which hosts serve a topic anywhere on the network. This tells it what one named domain hosts. The two are complementary. ## Specification The key words MUST, MUST NOT, SHOULD, SHOULD NOT, and MAY in this document are to be interpreted as described in RFC 2119. A domain hosting overlay services publishes a `metanet.overlays` object in the `/manifest.json` served at its root: ```json { "metanet": { "overlays": { "tm_example": "https://api.example.com", "ls_example": "https://api.example.com", "tm_other": "https://other.example.net/overlay" } } } ``` 1. Each key is the name of a [BRC-22](/brc/overlays/0022.md) topic manager or [BRC-24](/brc/overlays/0024.md) lookup service, exactly as it is named in submission and lookup requests. The [BRC-87](/brc/overlays/0087.md) naming conventions distinguish the two, so the map needs no further structure. 2. Each value is the base URL a client resolves that service's routes against. Those routes are defined by BRC-22, BRC-24 and the service's own specification, and MUST NOT be respecified here. 3. Services MAY name different hosts, including hosts the domain does not control. 4. A client MUST ignore keys it does not recognise. To resolve a domain, a client fetches `https:///manifest.json` and reads `metanet.overlays`. If the document, the object, or the entry for the service sought is absent, that domain does not offer that service; the client MUST NOT probe hostnames or contact a host the user did not name. A domain declares what it chooses to declare, secured by control of the domain. A client MUST NOT infer that a declared host is trustworthy, only that the domain claims it. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://hub.bsvblockchain.org/brc/overlays/0180.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.