feat: with subscription

Signed-off-by: kjuulh <contact@kjuulh.io>

crates/crunch-traits/src/transport.rs

@@ -1,4 +1,4 @@
-use std::sync::Arc;
+use std::{pin::Pin, sync::Arc};
 
 use async_trait::async_trait;
 
@@ -6,7 +6,19 @@ use crate::{errors::TransportError, EventInfo};
 
 #[async_trait]
 pub trait Transport {
+    type Stream: futures::Stream<Item = Vec<u8>>;
+
     async fn publish(&self, event_info: &EventInfo, content: Vec<u8>)
         -> Result<(), TransportError>;
+    async fn subscriber(
+        &self,
+        event_info: &EventInfo,
+    ) -> Result<Option<Self::Stream>, TransportError>;
 }
-pub type DynTransport = Arc<dyn Transport + Send + Sync + 'static>;
+
+pub type DynTransport = Arc<
+    dyn Transport<Stream = Pin<Box<dyn futures::Stream<Item = Vec<u8>> + Send>>>
+        + Send
+        + Sync
+        + 'static,
+>;