waku-org
/
specs
mirror of https://github.com/waku-org/specs.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

add failure definition

This commit is contained in:
Sasha 2024-07-09 23:45:34 +02:00
parent b264454e3d
commit 092b18e730
No known key found for this signature in database
1 changed files with 6 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
informational/req-res-reliability.md
View File

@ -17,6 +17,10 @@ This RFC describes set of instructions used across different [WAKU2](https://git
### Definitions
- Service node - provides services to other nodes such as relaying messages send by LightPush to the network or broadcasts messages from the network through Filter, usually serves responses;
- Light node - connects to and uses one or more service nodes via LightPush and/or Filter protocols, usually sends requests;
- Service node failure - can mean various things depending on the protocol in use:
- generic protocol failure - request is timed out or failed without error codes;
- LightPush specific failure - refer to [error codes](../standards/core/lightpush.md#examples-of-possible-error-codes) and consider request a failure when it is clear that service node cannot serve any future request, for example when service node does not have any peers to relay and returns `NO_PEERS_TO_RELAY`;
- Filter specific failure - we consider service node failing when it cannot serve [subscribe](https://github.com/vacp2p/rfc-index/blob/7b443c1aab627894e3f22f5adfbb93f4c4eac4f6/waku/standards/core/12/filter.md#subscribe) or [ping](https://github.com/vacp2p/rfc-index/blob/7b443c1aab627894e3f22f5adfbb93f4c4eac4f6/waku/standards/core/12/filter.md#subscriber_ping) request with OK status;
## Motivation
@ -43,10 +47,7 @@ To address this we suggest following metrics:
#### Pool of reliable service nodes
Light node should maintain a pool of reliable service nodes for each protocol.
In case service node fails to serve protocol request from a light node 3 times - light node should drop connection to it and a new service node should be connected and added to the pool instead.
Service node failure can mean various things depending on the protocol in use.
For LightPush we advice so refer to [error codes](../standards/core/lightpush.md#examples-of-possible-error-codes) and consider request a failure when it is clear that service node cannot serve any future request, for example when service node does not have any peers to relay and returns `NO_PEERS_TO_RELAY`.
For Filter we consider service node failing when it cannot serve subscribe or ping request with OK status.
In case service node [fails](./req-res-reliability.md#definitions) to serve protocol request from a light node 3 times - light node should drop connection to it and a new service node should be connected and added to the pool instead.
#### Selection of discovered service nodes
During discovery light node should filter out service nodes based on preferences before establishing connection.
@ -76,7 +77,7 @@ Our advice to use 2 service nodes at a time.
#### Retry on failure
When light node sends a message it must await for LightPush response from service node and check it for [possible error codes](../standards/core/lightpush.md#examples-of-possible-error-codes).
In case request failed without error code or response contains errors that can be temporary for service node (e.g `TOO_MANY_REQUESTS` or `NO_PEERS_TO_RELAY`) -
In case request failed without error code or response contains errors that can be temporary for service node (e.g `TOO_MANY_REQUESTS`) -
light node should try to re-send message after some interval and continue doing so until OK response is received or canceled.
Interval time can be arbitrary but we recommend starting with 1 second and increasing it on each failure during LightPush send.
Important to note that [per another recommendation](./req-res-reliability.md#pool-of-reliable-service-nodes) - light node should replace failing service node with another within pool of service nodes used by LightPush.