Ethereum Foundation DevCon 6 - Developer Infrastructure Track, 16 Oct 2022

Previous Meeting Next Meeting

⏯

youtube image

►

From YouTube: headlong: A Contract ABI and RLP Library for the JVM by Evan Saulpaugh | Devcon Bogotá

Description

Visit the https://archive.devcon.org/ to gain access to the entire library of Devcon talks with the ease of filtering, playlists, personalized suggestions, decentralized access on Swarm, IPFS and more.
https://archive.devcon.org/archive/watch/6/headlong-a-contract-abi-and-rlp-library-for-the-jvm/

I describe how I implemented the solidity Contract ABI specification to make encoding and decoding faster and therefore more scaleable while also improving usability. headlong can parse any function signature or JSON description at runtime and do the type-checking of inputs before encoding and of outputs during decoding.

I also discuss how the command-line interface uses human-to-machine and machine-to-machine RLP-based serialization formats to consume arguments and produce results.

Speaker(s): Evan Saulpaugh
Track: Developer Infrastructure
Keywords: developers,developers,developers

Follow us: https://twitter.com/efdevcon, https://twitter.com/ethereum
Learn more about devcon: https://www.devcon.org/
Learn more about ethereum: https://ethereum.org/

Devcon is the Ethereum conference for developers, researchers, thinkers, and makers.
Devcon 6 was held in Bogotá, Colombia on Oct 11 - 14, 2022.
Devcon is organized and presented by the Ethereum Foundation, with the support of our sponsors. To find out more, please visit https://ethereum.foundation/

A

A

Library it uh it doesn't do anything else. Really. It's just hyper focused it's used by Dune Unstoppable domains. I figured that uh I wanted to make a general Solution. That's like low level high performance that people can just build stuff on here's, some just rough benchmarks. For my laptop, um you can do like partial decoding of uh call data for ABI. So that's like the measured nanoseconds over there, so it works with bytes instead of strings. So it's a lot faster than uh some other tools, so yeah, just very few dependencies supposed to be lightweight.

A

It's just sort of uh the general design philosophy around it and yeah Java, so it does compatible with Android and kotlin, and um it's like, if you're, using it on like a web server using decoding large amounts of data. This is useful for something like that.

A

The other type of user I have is um like people are trying to work with, like an array of structs inside a struct and like other tools, aren't working for them so, uh like mine, can decode any arbitrary function, signature or data that matches any function signature, so here's the API for like the rlp stuff. This is different because uses an iterator pattern and it decodes on demand instead of uh eagerly yeah.

A

All these objects just sort of point at uh at a bite buffer and uh you can decode directly from the byte buffer on demand, and so it saves some time there and then here's like the ABI stuff. So all the objects are meant to be reused. Many times like the function, object and they're stateless, so you can share them across threads or between code there's, some decoding. It also deals with Json, so you can like parse Json and create a function from Json.

A

uh It also does event decoding, as added recently um so just hear some details on.

A

You know how I got the performance benefits from you know, using byte, buffer and pre-calculating things and and holding on to them for like multiple encodings and decodings yeah and there's some denial of service protection for if you're decoding, like untrusted data, that wants to allocate like a huge array, it'll throw an exception. Instead of like allocating a gigabyte of uh memory.

A

Yeah future work might involve um doing like more partial decodes like querying like nested tuples, so like going to a specific index and then, if that's a tuple, go ahead and index, and that and just pick out the thing you want to decode and just ignore everything else.

A

um But it requires like jumping around um the index and stuff and then yeah I've been talking to some people recently about a possible ABI V3.

A

So, um like I, wrote a command line interface that can encode arguments as rlp and uses a lot less uh bytes, because you don't have an offset and all this zero padding and stuff like that. So and then you can try that out. If you want headlong clis like the command line, interface and uh yeah faster, simpler software, Legos, I kind of just want people to uh you know be able to build um modular stuff.

A

Just so that you're not like weighted down by all these dependencies and like complex Frameworks, where you have to read all this documentation and um just build something to last and then special thanks to Victor dylapine, because uh he added some code that now I can decode events with headlong.

A

And thanks do you have any plans for SSD support, uh not right now, I thought about maybe implementing something separate for SSE, but uh I, don't know if I'm gonna, so maybe what does he uh good use? Cases for this Library I'll do an analytics uh start using it for like ingesting large amounts of data, so they can put it into databases and, like query it so like. If you have a lot of historical data lying around, do you want to decode like huge amounts of it and gain insights from data and stuff?

A

Otherwise, it's just designed to work in every possible case: nested, arrays, nested, tuples, tubular, Rays, drugs and stuff, oh and there's no code generation. So it's all just very uh traditional. That way.