Symbol implementation of UCAN spec
npm install symbol-ucanHere are a number of useful utilities provided for managing lists of attenuations aka capabilities.
UCAN is a beautifully unopinionated standard, but in order to make this more turn-key usable, we have had to opine. The possible segments supported by these utilities are READ, WRITE, CREATE, DELETE and superuser *.
Some of these utilities are really just for the convenience of working with any sort of UI for these capabilities.
``
export type AbilityTree = {
'READ': Array
'CREATE': Array
'WRITE': Array
'*': Array
};
export const abilityTree: AbilityTree = {
'READ': [],
'CREATE': ['READ'],
'WRITE': ['READ', 'CREATE'],
'*': ['READ', 'WRITE', 'CREATE', 'DELETE']
};
stringified. Secondly each with space is organized into namespace keys. This allows object traversal of abilities for a given namespace. - (obj: { [key:string]:Superuser|{[key:string]:string[]} }):Array simply flattens out an
AbilityObj into an attenuations list- stackedAbilities(abilities: Array):Array calls abilityObj and flattenAbilityObj to dedup a list of Capabilities.
- reduceAbilities(reduce: Array, abilities: Array):Array where the first argument is Capabilities you want to remove from a list of Capabilities. Returns the reduced Capability list.
- stackAbilities(abilities: Array):Array could almost seem redundant to
stackedAbilities !!except!! there is an important functionality within UCANs that needs to be considered. If you consider that giving someone WRITE ability would normally assume READ and CREATE as well. However, there is no such etymology within the UCAN functions. That's where we opine. If you stack abilities, all lesser abilities will be added to each namespace that has a greater ability. So it lengthens the total list of Capabilities to match how UCAN verify` functions. This way, for UI purposes, you only need the greatest possible ability to know all abilities. Of course UCAN is far more extensible than this, but this is a sound, time-tested, and simple approach to handling permissions. It only limits you inasmuch as you use these utilities - you can still do anything you wish with your UCAN implementation.