Add codec for TransactionMeta to enable more efficient data transfer and storage.

[joefitter]

Motivation

When requesting a base64 tx via RPC, the transaction is encoded as base64, however meta is provided in a fully-inflated format. The issue with this is any service that wishes to cache the result of getTransaction needs to implement JSON.stringify and JSON.parse replace functions to handle BigInts etc, and the size of the stored result is v large.

Also when parsing using plain JSON the branded types (Lamports, Address etc) are lost.

Example use case

/*
 *  {
 *    transaction: Base64EncodedDataResponse,
 *    meta: Base64EncodedDataResponse
 *  }
 */
const result = await client.rpc.getTransaction(txSignature, { encoding: "base64", encodeMeta: true }).send();
await env.CACHE.put(txSignature, JSON.stringify(result));

const { transaction, meta } = JSON.parse(await env.CACHE.get(txSignature));
const encodedMeta = getBase64Encoder().encode(meta)
const decodedMeta = getTransactionMetaDecoder().decode(encodedMeta);

// decodedMeta has the same data structure as would have been received by `rpc.getTransaction(sig, { encoding: 'json' })`

Details

A transactionMetaCodec would need to be added to encode and decode transaction meta from an array of bytes.

The functionality should be opt-in so as to not break existing implementations (encodeMeta flag or similar)

[ningthoujamSwamikumar]

@joefitter Hi. I am interested to work on this. Can I pick this up?

[mcintyre94]

This would be a nice idea, but as suggested I don't think it's something we can change in Kit. The rpc. functions are just directly converted to Solana JSON-RPC calls, and getTransaction does not support this flag. To achieve that we'd need to change the RPC.

We could definitely provide a codec for the TransactionMeta, which you could use to encode it to bytes, and then either store that or convert to base64. But the type of meta is quite fiddly depending on the options you pass to getTransaction so it'd lose some specificity.