@pamoja/codec

CBOR, JSON, and raw codecs behind one trait, delta and varint batch packing, and an f32 quantizer for metered links. One capability of pamoja, one memory-safe Rust core with bindings for TypeScript, Python, and C#.

Install

npm install @pamoja/codec
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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/codec.ts:

import { Quantizer, fromCbor, packSamples, toCbor, unpackSamples } from '@pamoja/codec'

// The same reading as JSON and as CBOR. Nothing is lost, and 21.5 rides as a
// half-precision float, the shortest form RFC 8949 allows for it.
const reading = { c: 21.5, ok: true }
const asJson = Buffer.from(JSON.stringify(reading))
const cbor = toCbor(reading)
console.log(`json      ${asJson.length} bytes`)
console.log(`cbor      ${cbor.length} bytes`)

// A gateway that speaks JSON gets it back unchanged, so the compact form is a transport
// choice rather than a different data model.
const restored = fromCbor(cbor)
console.log(`back to json, unchanged: ${JSON.stringify(restored) === JSON.stringify(reading)}`)

// A batch of readings packs to a count, then the difference between each sample and the
// one before it. Successive readings differ by very little, so the differences cost about
// a byte each where the samples would cost eight.
const samples = [10, 11, 13, 12, 900]
const packed = packSamples(samples)
console.log(`batch     ${samples.length} samples in ${packed.length} bytes`)
console.log(`unpacked  ${unpackSamples(packed).join(', ')}`)

// Readings that arrive as floats pack the same way once a scale is chosen. Nothing in the
// bytes records that scale, so the sender and the receiver have to agree on it.
const quantizer = new Quantizer(100)
const celsius = [20.0, 20.1, 20.2, 20.3]
const packedCelsius = quantizer.encode(celsius)
const recovered = quantizer.decode(packedCelsius)
console.log(`degrees   ${celsius.length} readings in ${packedCelsius.length} bytes`)
console.log(`recovered ${[...recovered].map((v) => v.toFixed(1)).join(', ')}`)
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The same capability in every language

Documentation

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

License

MIT