IPLD CAR Transactions (txs)

1. Use IPLD Blocks to add to IPLD one transaction at a time.
2. Import your commited transactions back into a DAG to build it further.

All Imports

import { Transaction, encode, createDagRepo, importBuffer } from '@douganderson444/ipld-car-txs';

Why?

Tag Dag Repo Builder. Because when you want to build a local first DAG one step at a time, and save each step into an external source (database, Arweave, p2p, wherever) you need a mechanism to do this.

With IPFS DAG, it's all or nothing, so you would be saving a lot of duplicate data. But with IPLD, if we break the Dag building down into transactions, then we can save each transaction and avoid this duplication.

We're building a DAG here, so previous CIDs from deeper down in the DAG can be linked to our current transaction we are building. So we also need a way to GET those links, with a label or a tag. So say I am building "Mobile Phone Number" as a Tag in my Dag, I would first:

cid = dag.put({"Mobile Phone Number": {value: : "555-1234"}})

Now any time someone looks up rootCID["Mobile Phone Number"].value they will get "555-1234".

But I forgot to add an area code, so I need to update:

newCid = dag.put({"Mobile Phone Number": {value: "555-555-1234", prev: cid}})

Now rootCID["Mobile Phone Number"].value points to the new number, area code included.

But if I go to save newCid to a database by exporting the CAR using ipfs.dag.export(newCid) I am ALSO going to save the data at prev which I may have already paid to save, so I am paying again for it. What we want to do is split the DAG building and saving process up into steps (transactions) so that we save each segment individually and thus avoid duplication.

Install

npm install @douganderson444/ipld-car-txs

Usage API

Using ipfs.dag already? Extend the functionality with

Object.assign(ipfs.dag, yourDagRepo);

Now you should be able to use ipfs.dag.tx.add(tag, {key: value})

DagRepo usage

You can leave createDagRepo(options) config options blank and the library will assume reasonable defaults for you.

import { createDagRepo } from '@douganderson444/ipld-car-txs';

const run = async () => {
	let dag = await createDagRepo({
		path: 'ipfs', // default is 'ipfs'
		persist: false, // default is false; you can set true for browser IndexedDB
		ipld: { codecs: {} } // ipld options, defaults include dagCBOR & dagJOSE
	});

	let key = 'Mobile';
	let key2 = 'Landline';

	await dag.tx.add(key, { number: '555-1234' });
	const firstBuffer = await dag.tx.commit(); // save this somewhere else, like Arweave

	await dag.tx.add(key, { number: '212-555-1234' }); // now there is a Mobile/prev/number, 555-1234
	await dag.tx.add(key2, { number: '555-555-1234' });
	const secondBuffer = await dag.tx.commit(); // data not duplicated, only new data needs to be saved

	let currentNumber = (await dag.get(dag.rootCID, { path: `/${key}/obj/number` })).value;
	console.log({ currentNumber }); // 212-555-1234

	let prevNumber = (await dag.get(dag.rootCID, { path: `/${key}/prev/obj/number` })).value;
	console.log({ prevNumber }); // 555-1234

	// I can rebuild the dag from transactions on another machine
	let rebuiltDag = await createDagRepo({ path: 'rebuiltDag' }); // make a barebones dag repo for fast

	// if you have the last buffer, then root will equal dag.rootCID
	const root = await rebuiltDag.importBuffers([firstBuffer, secondBuffer]);

	// get the latest value of a Tag using dag.latest(tag)
	const latestObj = await rebuiltDag.latest(key);

	let rebuiltCurrent = (await rebuiltDag.get(dag.rootCID, { path: `/${key}/obj/number` })).value;
	console.log({ rebuiltCurrent });
};

run();

Encode(value)

For convenience, encode(value) is also exported, which allows you to encode objects and raw bytes into a Block, returning Block which is {value, bytes, cid}.

const value = { hello: 'world' }; // object
const value = new TextEncoder().encode(JSON.stringify({ hello: 'world' })); // or bytes
const { value, bytes, cid } = encode(value);

Import Buffer into ipfs.dag

Normally you can only ipfs.dag.import() a car file, but with this library you'd want to import a buffer. You can also use importBuffer(dag: DagAPI, buffer: Uint8Array) on your DagAPI:

import { importBuffer } from '@douganderson444/ipld-car-txs';

await importBuffer(ipfs.dag, someCarByteBuffer);

Credits

Extended from the inspiration of car-transaction

Build notes

Until sveltejs/kit/issues/2040 is fixed, we have to programmatically change the .ts extension to .js in ./src/lib/index.ts