Project Description
This project adds a new network protocol to Urbit to handle notifying subscribers when a new datum is published. A rough spec can be found here↗. Without this protocol, upcoming "solid-state subscriptions", which use the remote scry protocol, will have too much latency for chat.
Ideally this project would be done by two engineers, but one experienced C programmer could also do it. The apprentices will write this code themselves, not as part of a larger team. This work is entirely in Vere; any supporting work in the Arvo kernel will be handled by the mentor. ~rovnys-ricfer, who wrote the spec and a lot of the existing Urbit networking code, will mentor the engineers.
Deliverables
The major deliverable is a new Ames I/O driver in Vere that implements the notifications protocol.
User Stories
- Live subscribers receive notifications promptly and handle them correctly.
- Sessions die and restart properly.
- Memory is freed on the publisher ship when a session dies.
- Heartbeat packets keep firewall pinholes open.
- Notifications are delivered reliably even when some packets get lost.
Prerequisites
- Proficiency in C
- Basic understanding of the Fine and Ames network protocols and packet formats
- The symmetric routing project (notifications use that routing scheme)
Educational Outcomes for the Apprentice
The apprentice will learn about:
- Firewall pinholes
- Bit twiddling in Hoon and C
- The Arvo/Vere interface
Responsibilities of the Mentor
- Clarify spec and implementation plan
- Answer questions about existing code
- Code review: style, correctness, performance, patterns and anti-patterns
- Help with testing and deployment strategies
Duration and Compensation
Expected duration is two months. 1 star paid at completion of apprenticeship