NameSpaced IDs (NSIDs)#

NameSpaced IDs (NSIDs) are used throughout ATP to identify methods, records types, and other semantic information.

NSIDs use Reverse Domain-Name Notation with the additional constraint that the segments prior to the final segment must map to a valid domain name. For instance, the owner of example.com could use the ID of com.example.foo but could not use com.example.foo.bar unless they also control foo.example.com. These rules are to ensure that schemas are globally unique, have a clear authority mapping (to a registered domain), and can potentially be resolved by request.

Some example NSIDs:

com.example.status
io.social.getFeed
net.users.bob.ping

Grammar#

alpha     = "a" / "b" / "c" / "d" / "e" / "f" / "g" / "h" / "i" / "j" / "k" / "l" / "m" / "n" / "o" / "p" / "q" / "r" / "s" / "t" / "u" / "v" / "w" / "x" / "y" / "z" / "A" / "B" / "C" / "D" / "E" / "F" / "G" / "H" / "I" / "J" / "K" / "L" / "M" / "N" / "O" / "P" / "Q" / "R" / "S" / "T" / "U" / "V" / "W" / "X" / "Y" / "Z"
number    = "1" / "2" / "3" / "4" / "5" / "6" / "7" / "8" / "9" / "0"
delim     = "."
segment   = alpha *( alpha / number / "-" )
authority = segment *( delim segment )
name      = segment
nsid      = authority delim name
nsid-ns   = authority delim "*"

The nsid-ns (a "namespace") can be used in certain situations to designate all names under a namespace, eg com.example.*.

Authority model#

Every NSID asserts a single authority which is identified as the segments prior to the final segment which are then reversed.

com.example.thing
^^^^^^^^^^^--------> example.com

The authority controls the namespace of all names within it, however there is no hierarchy or relationship between authorities. That is, the domain example.com does not hold any authority over sub.example.com, and therefore com.example.* is considered completely independent of com.example.sub.*.

Parsing#

NSIDs are comprised of an "authority" and a "name". Some example resolutions of NSIDs to authorities and names:

NSID	Authority	Name
com.example.status	example.com	status
io.social.getFeed	social.io	getFeed
net.users.bob.ping	bob.users.net	ping

The domain can be extracted through the following algorithm:

function getNSIDAuthority (nsid) {
  // split the nsid into segments
  const parts = nsid.split('.')
  // remove the last segment
  parts.pop()
  // reverse the order of the segments
  parts.reverse()
  // rejoin the segments
  return parts.join('.')
}

The name can be extracted through the following algorithm:

function getNSIDName (nsid) {
  // split the nsid into segments
  const parts = nsid.split('.')
  // return the last segment
  return parts.pop()
}