C.3 DiscoveryUrl Mapping

An DiscoveryUrl has the form:

scheme://hostname:port/path

scheme: the protocol used to establish a connection.

hostname: the domain name or IPAddress of the host where the Server is running.

port: the TCP port on which the Server is to be found.

path: additional data used to identify a specific Server.

Table C.3 – DiscoveryUrl to DNS SRV and TXT Record Mapping
URL Field Mapping
scheme

The scheme maps onto SRV record service field.

The following mappings are defined at this time:

The OPC UA service names are assigned by IANA.

Additional service names may be added in the future.

The endpoint shall support the default transport profile for the scheme.

hostname

The hostname maps onto the SRV record target field.

If the hostname is an IPAddress then it shall be converted to a domain name.

If this cannot be done then LDS shall report an error.

portThe port maps onto the SRV record port field.
pathThe path maps onto the path string in the TXT record (see Table C.2).

Suitable default values should be chosen for fields in a SRV record that do not have a mapping specified in Table C.3. e.g. TTL=86400, class=IN, priority=0, weight=5