Sharing Properties Across Requests
The StreamProperties injectable provides an interface to:
-
Consume properties set by other policies that are processing the same request.
-
Broadcast properties so that the other policies can consume them.
To share data, StreamProperties implements the PropertyAccessor trait:
pub trait PropertyAccessor {
fn read_property(&self, path: &[&str]) -> Option<Bytes>;
fn set_property(&self, path: &[&str], value: Option<&[u8]>);
}The following example shows a simple filter that reads a property from the stream and then writes another parameter to it:
async fn request_filter(stream: StreamProperties) -> Flow<()> {
let incoming = String::from_utf8(stream.read_property(&["incoming_property"]).unwrap_or_default()).unwrap_or_default();
logger::info!("Recieved incoming prop {}", incoming);
let outgoing = "outgoing".as_bytes();
stream.set_property(&["outgoing_property"], Some(outgoing));
Flow::Continue(())
}
#[entrypoint]
async fn configure(launcher: Launcher) -> Result<()> {
let filter = on_request(|stream| request_filter(stream));
launcher.launch(filter).await?;
Ok(())
}