@pamoja/zenoh

Zenoh key expressions: validity, canonical form, matching, and whether two expressions share or cover keys. One capability of pamoja, one memory-safe Rust core with bindings for TypeScript, Python, and C#.

Install

npm install @pamoja/zenoh
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This pulls in @pamoja/native, the compiled engine. npm install pamoja is the whole framework in one package.

Example

The test that runs in CI, spliced here as it ran.

From bindings/node/guides/zenoh.ts:

import { keyexpr } from '@pamoja/zenoh'

// A key expression names a set of keys. Chunks sit between slashes, `*` stands for exactly one
// chunk, whatever it holds, and `**` for any number of them, including none.
const selects = (pattern: string, key: string): string => {
  const verdict = keyexpr.matches(pattern, key) ? 'covers' : 'misses'
  return `${verdict.padEnd(10)}${pattern} ${verdict} ${key}`
}
console.log(selects('farm/*/power', 'farm/t7/power'))
console.log(selects('farm/*/power', 'farm/substation/power'))
console.log(`${selects('farm/*/power', 'farm/row2/t14/power')}, since * is exactly one chunk`)
console.log(selects('farm/**/power', 'farm/row2/t14/power'))
console.log(`${selects('farm/**/alarm', 'farm/alarm')}, where ** is no chunk at all`)

// `$*` stands for any run of characters inside one chunk, so it selects on part of a name.
console.log(selects('farm/t$*/power', 'farm/t7/power'))
console.log(selects('farm/t$*/power', 'farm/substation/power'))

// One set of keys has one canonical spelling, and a Zenoh session accepts no other.
for (const written of ['farm/*/**/power', 'farm/**/*/power', 'farm/**/**/power']) {
  const canonical = keyexpr.canonize(written)
  if (keyexpr.isCanon(written)) {
    console.log(`canonical ${written}, as written`)
  } else {
    console.log(`rewritten ${written} is spelled ${canonical}`)
  }
}

// Joining places one expression beneath another, and canonizes the seam between them.
for (const [prefix, suffix] of [
  ['farm/t7', 'power'],
  ['farm/**', '*/power'],
]) {
  console.log(`joined    ${prefix} and ${suffix} make ${keyexpr.join(prefix, suffix)}`)
}

// A malformed expression is refused rather than repaired into something plausible.
for (const [written, why] of [
  ['farm//power', 'a chunk is empty'],
  ['farm/t7*/power', '* stands alone in its chunk, or after $'],
  ['farm/t7/power?', '? and # are reserved'],
]) {
  if (!keyexpr.isValid(written) && keyexpr.canonize(written) === null) {
    console.log(`malformed ${written}, since ${why}`)
  }
}
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The same capability in every language

Documentation

• @pamoja/zenoh reference, every class, function, and type this package exports.
• The Zenoh keys guide, with the same example in Rust, Python, and C#.
• Every capability, and the install page.

License

MIT