Erlang - UUID Server

A simple UUID generator for use in applications.

This project implements most UUID versions and... generally... adheres to RFC 4122. In this revision the API has been simplified and the version 2 UUID implementation has been removed. All UUID generation is done through a gen_server. Requests UUIDs can be batched. The last change is the ability to set two options: MAC privacy and UUID version utilized.

I favor simplicity over strict ahderence, a common theme in my projects. Due to how namespace UUIDs are generated, it is recommended to convert any pre-existing UUIDs in persistent storage.

General Behavior / Assumptions:

• One instance running over complete system; used in one EVM.
• This implementation only considers the Leach-Salz / RFC-4122 UUID variant.
• The output is binary, not strings.
• UUIDs can be converted to/from binary and string (as lists) formats.

Version 1:

• The clock sequence remains constant. No collisions can be produced at current CPU clock speeds.
• Unless specified during start up a random node ID will be used instead of the MAC address.

Version 4:

• As per RFC 4122.

Version 3/5:

• Erlang defaults to network byte order and is considered as the "native environment." No byte order conversions are done.
• As per the RFC "The concept of a name and name space should be broadly construed..." Any erlang term can be used as a name or name space. The hash function is passed <<term_to_binary(NameSpace), term_to_binary(Name)>>.
• Erlang terms, not UUIDs, are used as name space identifiers. No predetermined values are used (RFC 4122 Appendix C).

Usage

Starting:

• start_link/0: Equivalent to [].
• start_link([Options]):

Options:

• (empty): Default behavior - UUID V1; hidden MAC.
• {privacy, true|false}: Uses MAC or random node ID for V1.
• {version, 1 - 5}: Sets UUID generation method.

API:

• nil/0: Returns <<0:128>>

• new/0: Returns one V1 or V4 UUID; gen_server state must indicate v1 or v4.

• new/1: (Tuple) Returns a single V3 or V5 UUID.

• new/1: (List) Returns n V3 or V5 UUIDs in a list.

• new/1: (Integer) Returns n V1 or V4 UUIDs in a list.

• setopt/1: Set MAC privacy for subsequent UUID generation; sets version for UUID generation.

• to_string/1: Returns list representation of binary UUID in proper text format.

• to_binary/1: Returns binary representation of text (as list) formatted UUID.

• calibrate/0: Indicates to gen_server to recompute time offset used in time-based UUIDs.

• get_utc/1: Get creation time of V1 UUIDs in nanoseconds.

• get_utc/2: Specify time interval (second, milli..., micro..., nano...)

References

RFC 4122: A Universally Unique IDentifier (UUID) URN Namespace

DCE 1.1: Authentication and Security Services