diff --git a/src/runtime2/component/component.rs b/src/runtime2/component/component.rs
index d68a0207767ee01904a1e6028d7742ccf9f63d8d..73ee7e4cc4ce5f8a272539990fa31a4ae357d8b0 100644
--- a/src/runtime2/component/component.rs
+++ b/src/runtime2/component/component.rs
@@ -1,3 +1,4 @@
+use crate::protocol::eval::EvalError;
 use crate::runtime2::*;
 use super::CompCtx;
 
@@ -8,7 +9,17 @@ pub enum CompScheduling {
     Exit,
 }
 
+/// Generic representation of a component (as viewed by a scheduler).
 pub(crate) trait Component {
-    fn handle_message(sched_ctx: &mut SchedulerCtx, comp_ctx: &mut CompCtx, message: Message);
-    fn run(sched_ctx: &mut SchedulerCtx, comp_ctx: &mut CompCtx) -> CompScheduling;
+    /// Called if the component is created by another component and the messages
+    /// are being transferred between the two.
+    fn adopt_message(&mut self, comp_ctx: &mut CompCtx, message: DataMessage);
+
+    /// Called if the component receives a new message. The component is
+    /// responsible for deciding where that messages goes.
+    fn handle_message(&mut self, sched_ctx: &mut SchedulerCtx, comp_ctx: &mut CompCtx, message: Message);
+
+    /// Called if the component's routine should be executed. The return value
+    /// can be used to indicate when the routine should be run again.
+    fn run(&mut self, sched_ctx: &mut SchedulerCtx, comp_ctx: &mut CompCtx) -> Result<CompScheduling, EvalError>;
 }
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