# Ethereum Protocol Fellowship - The Third Cohort (Update 3) This is the third update for Ethereum Protocol Fellowship - The Third Cohort. In the third and fourth weeks, I continued with setting up the project ([here](https://github.com/Vid201/aa-bundler/)) and worked on defining the overall architecture in more detail. ## Updates After briefly starting the development, I decided to instead focus on defining the architecture in more detail (in a separate document). This document will be updated throughout the fellowship and onwards. List of updates: 1. Completed the first draft of the architecture: [link](https://hackmd.io/@Vid201/aa-bundler-rust). 2. Diving deep into the codebase of [Erigon](https://github.com/ledgerwatch/)-based projects to learn more about structuring the modular Ethereum client: [erigon](https://github.com/ledgerwatch/erigon), [erigon-lib](https://github.com/ledgerwatch/erigon-lib/), [akula](https://github.com/akula-bft/akula), and [interfaces](https://github.com/ledgerwatch/interfaces). This took the most time. 3. Contacted the [eth-infinitism](https://github.com/eth-infinitism/) team (in contact with joavw and dror) to learn what they are working on bundlers. They were very helpful, and we set up a Telegram chat for future communication and help/questions I'll have. They are working on specs and a test suite, which is helpful for the bundler implementation I am working on (and, of course, for the whole ecosystem of AA to achieve full interoperability between different implementations). 4. Talking with another fellow @will#8617 on Discord about possible ways to collaborate. ## Next steps In the next two weeks, I plan to share the defined architecture with some people for feedback. After that, I will continue implementing the bundler and concurrently update the architecture document with new findings.