Naming System

Naming systems are useful to allow for users (clients) to find servers. The most widely known implementation is DNS.

• A name can be absolute or relative.

Goal

• Associate a nasme with a resource.

Why do we need names

• Locate resources
• Share resources
• Easier to communicate

Concepts

• Name: identifies, given name by a human with semantic meaning for humans.
• Identifier: identifies, system controlled.
• Address: identifier that allows for direct access.
• Namespace: set of rules that define the universe of admissible names.
• Authority:
  • Defines the rules of naming management.
  • Must guarantee that all rules are satisfied.
  • Authority can be delegated (hierarchies).
  • Examples:
    • IP Address –> IANA
    • Ethernet –> Xerox and manufacturer
    • UUID –> IETF Standard
    • DNS –> IANA/ICANN + Delegation

Namespace Properties

• Uniqueness: in a certain context, a name can only be associated with one object to avoid ambiguity. How to guarantee?
  • Central Attribution
    • High latency, single point of failure
    • Public IP addresses, Ethernet addresses
  • Local Attribution with Broadcast
    • Complicated on a large scale
    • Simple and useful in local networks

Practical Solutions for Global Naming

Unstructured Naming

• Can be independently attributed by any context
• Can be generated in a random or pseudorandom way
• Example: GUID, UUID

Hierarchy Naming

• Global names composed by concatenation of local names
• Example: phone numbers, DNS addresses, file names

Homogeneity and Heterogeneity

• Homogenous
  • Single component (e.g., Ethernet address)
  • Multiple components with the same structure and meaning (e.g., UNIX pathname)
• Heterogenous
  • Multiple components with structures and different meanings. E.g.:
    • Windows pathname: C:/a/b/c
    • URL: http://machine[:port]/my/dir

Pure vs Impure Names

• Impure: parts of the name are used for its resolution (e.g., URLs, IPs).
• Pure: does not locate the object, just identifies it (e.g., UUIDs, URNs).
  • Really complicated to implement.
  • Question: IPFS names are pure, right? If so, they are supposed to be really difficult to impalement. But not impossible. Needs investigation and thought. I was taught that this strategy is impractical because we don’t know where to start the search of the object. However, since IPFS uses a DHT and the object names are somewhat related to the user’s own Peer ID, then there is a way to know where to start looking for the object. So… is it pure or not?