eddn

Subscribe to journal events from the EDDN ZMQ event stream.

Usage

To get started, add the following to your Cargo.toml:

eddn = "*"

An example live stream can be demonstrated with the envelope example:

cargo run --example envelope

Disconnects

A subscription outlives the connection carrying it. subscribe documents the three ways one stops working and what notices each. In short: libzmq rebuilds a connection that closes, heartbeats find one that has died without closing within 15 seconds, and a gateway that answers heartbeats while publishing nothing is waited out for the stall_timeout given to subscribe. All three are traced as they happen, so install a tracing subscriber or none of it will be heard.

That timeout is the caller's to pick, from how quiet the gateway is expected to go, and None says not to watch for it at all. There is no default because the answer belongs to the gateway rather than to this crate.

Watching any of it happen means standing in for the gateway, since EDDN cannot be asked to have a bad day on cue. A ZeroMQ PUB socket publishing compressed envelopes is enough for the first case: kill it and a subscriber picks the next connection up. Leave it running while it stops publishing and the stall timeout is what ends the wait. The second case needs something between the two that stops passing messages while holding the connection open, which is the one thing neither end can do to itself.