The SRV record has a TXT record associated with it that provides additional information about the DiscoveryUrl. The format of this record is a sequence of strings prefixed by a length. This specifications adopts the key-value syntax for TXT records described in DNS-SD.
Table 113 defines the syntax for strings that may in the TXT record.
Table 113 – DNS TXT Record String Format
|
Key-Value Format |
Description |
|
path=/<path> |
Specifies the text that appears after the port number when constructing a URL. This text always starts with a forward slash (/). |
|
caps=<capability1>,<capability2> |
Specifies the capabilities supported by the Server. These are short (<=8 character) strings which are published by the OPC Foundation (see Annex D). The number of capabilities supported by a Server should be less than 10. |
The MulticastExtension shall convert DiscoveryUrls to and from these SRV records.