# Built-in Registry Server

> Run the IS-04 registry inside Buttons so NMOS nodes can register with it, advertise it over mDNS or DNS-SD, and serve IS-09 system parameters.

Running the built-in Registry Server lets Buttons act as the shared directory that NMOS nodes on your network register into, so devices can be found by anything that queries the registry (including Buttons itself) without entering an address for every device by hand. This is useful when you don't already have a separate registry appliance, or when you want Buttons to be the source of truth for a facility's NMOS resources. Before you begin You need: The NMOS feature enabled (on by default). Access to Settings → NMOS . Awareness of which network interface and port the registry should be reachable on, and whether the nodes that need to register can reach it. Turn on the Registry Server Open Settings → NMOS . Under Registry server , turn on Enable NMOS Registry server . Set Registry instance 1 port , the TCP port the IS-04 Registration and Query API listens on. Select Save . Once enabled, Buttons accepts NMOS node registrations and serves the IS-04 Query API. In stand-alone mode, Buttons supports a single registry instance: running more than one requires an HA deployment. Let nodes find the registry automatically Nodes can discover a registry in two ways. Use whichever suits your network: mDNS : Buttons announces the registry on the local network itself. This is the simplest option, but mDNS doesn't usually reach beyond one subnet. DNS-SD (unicast DNS) : the registry is listed in your network's DNS server. You set this up on your DNS server, outside Buttons, and it works across subnets. See the AMWA NMOS IS-04 specification for how nodes use each method. To announce the registry over mDNS, turn on Announce NMOS Registry instances on mDNS . Buttons then advertises enabled registry instances with the _nmos-register , _nmos-registration , and _nmos-query records nodes look for. These fields shape the advertisement: Registry instance 1 mDNS service name : the base instance name published in the discovery records. Registry instance 1 advertised host or IP : an optional hostname or address to expose instead of this machine's default mDNS host. Leave it blank to use the machine's default. Registry instance 1 priority : the mDNS priority ( pri TXT record) advertised for this instance. Lower values are preferred, which matters if more than one registry is reachable on the network. If a node can't use mDNS (for example, because it sits on a different subnet), use DNS-SD instead, or point the node at the registry manually in its own configuration, using this instance's address and port. Expose public endpoints for a NAT or multi-interface host If Buttons is reachable at a different address than the one nodes would otherwise detect (behind NAT, or on a host with more than one network interface), add one or more entries under Registry instance 1 public endpoints . These optional HTTP or HTTPS endpoints are advertised by the Node API instead of the request host, so nodes register using an address that's actually reachable for them. Confirm nodes can register Point a node's own registration configuration at this registry, either through mDNS or DNS-SD discovery or by entering this instance's address and port directly. Open Settings → NMOS and select Inspect registry under Inspect Registry . Confirm the node's resources appear, and that further changes on the node are reflected as live updates. Optional: serve IS-09 system parameters IS-09 lets registered nodes pull global timing and heartbeat configuration from Buttons instead of needing it configured on every device individually. Under Registry server , turn on Enable IS-09 System API endpoints to serve the /x-nmos/system/v1.0 endpoints. Set IS-09 heartbeat interval : how often nodes should heartbeat to the Registration API, in seconds. Set IS-09 PTP announce receipt timeout : the number of PTP announce intervals allowed before a timeout. Set IS-09 PTP domain number : the PTP domain number advertised in the System API's global configuration. Select Save . Decide how Buttons itself adopts from this registry Running the registry doesn't automatically make Buttons treat every node registered into it as adopted: that's a separate choice, made under NMOS Controller discovery on the same Settings → NMOS page. Setting Registry adoption strategy to Use Internal Registry has Buttons treat its own built-in registry as its adoption source automatically. Leaving it at Only manual adoption lets you add a Registry connection yourself and choose exactly which nodes to adopt, see Connect Buttons to an NMOS Registry . A Registry connection that an NMOS setting creates for you is marked in the NMOS connection list, so you can tell it apart from one you added yourself: Internal : the connection to the built-in registry, created by Use Internal Registry . Its setup page explains this and has an Open NMOS settings button. Its Connection Mode reads Internal Registry , and Registry UUIDs from Discovery Records isn't shown, because it always follows the built-in registry. Managed : a connection created by the global Registry adoption strategy setting. Hover the badge to see which setting created it. On either kind you can turn the connection off and on, and change its node adoption settings. Everything else is controlled by the NMOS setting that created it, so change it there instead. If you get stuck What you see What to try A node never appears in Inspect registry . Confirm the node is actually configured to register with this instance's address and port, and that mDNS or your manual configuration reaches it. If it's reaching the registry but still not appearing, the registry service's own logs record a "Rejected NMOS registration" warning with the specific reason (for example, a resource missing a required IS-04 field) whenever it refuses a registration attempt outright. Inspect registry is unavailable. Enable the Registry server first: the inspector only works once registration is active. A node on another subnet can't find the registry via mDNS. Set up DNS-SD on your network's DNS server, or configure that node with this instance's address and port directly. Nodes register, but Buttons never adopts them. Check Registry adoption strategy under NMOS Controller discovery : manual adoption strategies require you to add a Registry connection or adopt nodes yourself. Where to go next Connect Buttons to an NMOS Registry , to adopt specific nodes a registry already knows about. Configure NMOS connections , for endpoint and behavior settings once nodes are adopted.