diff --git a/examples/client.rs b/examples/client.rs
index da7847b..14a1484 100644
--- a/examples/client.rs
+++ b/examples/client.rs
@@ -6,9 +6,9 @@ struct Data;
 
 impl Method for Data {
     const NAME: &'static str = "data";
-    type Request = ();
-    type Response = ();
-    type Error = ();
+    type Request = String;
+    type Response = String;
+    type Error = String;
 }
 
 #[tokio::main(flavor = "current_thread")]
@@ -17,15 +17,19 @@ async fn main() -> session_rs::Result<()> {
 
     session.start_receiver();
 
-    println!("{:?}", session.request::<Data>(()).await?);
+    println!(
+        "Hi: {:?}",
+        session
+            .request::<Data>("Hello from client".to_string())
+            .await?
+    );
 
-    session
-        .on::<Data, _>(async |i, d| {
-            println!("Ok {i} {d:?}");
-
-            Ok(())
-        })
-        .await;
+    println!(
+        "Invalid data response: {:?}",
+        session
+            .request::<Data>("invalid_data".to_string())
+            .await?
+    );
 
     tokio::time::sleep(tokio::time::Duration::from_millis(1000)).await;
 
diff --git a/examples/server.rs b/examples/server.rs
index 770f39d..0d6fb8e 100644
--- a/examples/server.rs
+++ b/examples/server.rs
@@ -8,9 +8,9 @@ struct Data;
 
 impl Method for Data {
     const NAME: &'static str = "data";
-    type Request = ();
-    type Response = ();
-    type Error = ();
+    type Request = String;
+    type Response = String;
+    type Error = String;
 }
 
 #[tokio::main(flavor = "current_thread")]
@@ -32,7 +32,17 @@ async fn main() -> session_rs::Result<()> {
 
             session.start_receiver();
 
-            session.on::<Data, _>(async |_, _| Ok(())).await;
+            session
+                .on::<Data, _>(async |_, req| {
+                    println!("Msg from client: {req}");
+
+                    if req == "invalid_data" {
+                        return Err("Invalid data".to_string());
+                    }
+
+                    Ok("Hello from server".to_string())
+                })
+                .await;
         });
     }
 }