Merge pull request #26 from karthik2804/add-topic-name

add topic name metadata calling the guest handler

examples/mqtt-app/src/lib.rs

@@ -1,15 +1,16 @@
 use chrono::{DateTime, Utc};
-use spin_mqtt_sdk::{mqtt_component, Payload};
+use spin_mqtt_sdk::{mqtt_component, Metadata, Payload};
 
 #[mqtt_component]
-async fn handle_message(message: Payload) -> anyhow::Result<()> {
+async fn handle_message(message: Payload, metadata: Metadata) -> anyhow::Result<()> {
     let datetime: DateTime<Utc> = std::time::SystemTime::now().into();
     let formatted_time = datetime.format("%Y-%m-%d %H:%M:%S.%f").to_string();
 
     println!(
-        "{:?} Message received by wasm component: '{}'",
+        "{:?} Message received by wasm component: '{}' on topic '{}'",
         formatted_time,
-        String::from_utf8_lossy(&message)
+        String::from_utf8_lossy(&message),
+        metadata.topic
     );
     Ok(())
 }

sdk/macro/src/lib.rs

@@ -17,9 +17,9 @@ pub fn mqtt_component(_attr: TokenStream, item: TokenStream) -> TokenStream {
                 #preamble
             }
             impl self::preamble::Guest for preamble::Mqtt {
-                fn handle_message(payload: ::spin_mqtt_sdk::Payload) -> ::std::result::Result<(), ::spin_mqtt_sdk::Error> {
+                fn handle_message(payload: ::spin_mqtt_sdk::Payload, metadata: ::spin_mqtt_sdk::Metadata) -> ::std::result::Result<(), ::spin_mqtt_sdk::Error> {
                     ::spin_mqtt_sdk::executor::run(async move {
-                        match super::#func_name(payload)#await_postfix {
+                        match super::#func_name(payload, metadata)#await_postfix {
                             ::std::result::Result::Ok(()) => ::std::result::Result::Ok(()),
                             ::std::result::Result::Err(e) => {
                                 eprintln!("{}", e);

sdk/src/lib.rs

@@ -17,4 +17,4 @@ pub mod wit {
 pub use wit_bindgen;
 
 #[doc(inline)]
-pub use wit::spin::mqtt_trigger::spin_mqtt_types::{Error, Payload};
+pub use wit::spin::mqtt_trigger::spin_mqtt_types::{Error, Metadata, Payload};

spin-mqtt.wit

@@ -15,15 +15,20 @@ interface spin-mqtt-types {
       exactly-once,
   }
 
+  // metadata associated with the payload
+  record metadata {
+        topic: string,
+  }
+
   /// The message payload.
   type payload = list<u8>;
 }
 
 world spin-mqtt {
-  use spin-mqtt-types.{error, payload};
+  use spin-mqtt-types.{error, metadata, payload};
 
   /// The entrypoint for a Mqtt handler in wasm component  
-  export handle-message: func(message: payload) -> result<_, error>;
+  export handle-message: func(message: payload, metadata: metadata) -> result<_, error>;
 }
 
 world spin-mqtt-sdk {

src/lib.rs

@@ -15,6 +15,8 @@ wasmtime::component::bindgen!({
     async: true,
 });
 
+use spin::mqtt_trigger::spin_mqtt_types as mqtt_types;
+
 pub(crate) type RuntimeData = ();
 pub(crate) type _Store = spin_core::Store<RuntimeData>;
 
@@ -115,7 +117,7 @@ impl TriggerExecutor for MqttTrigger {
     async fn run(self, config: Self::RunConfig) -> anyhow::Result<()> {
         if config.test {
             for component in &self.component_configs {
-                self.handle_mqtt_event(&component.0, b"test message".to_vec())
+                self.handle_mqtt_event(&component.0, b"test message".to_vec(), "test".to_string())
                     .await?;
             }
 
@@ -155,15 +157,20 @@ impl TriggerExecutor for MqttTrigger {
 }
 
 impl MqttTrigger {
-    async fn handle_mqtt_event(&self, component_id: &str, message: Vec<u8>) -> anyhow::Result<()> {
+    async fn handle_mqtt_event(
+        &self,
+        component_id: &str,
+        message: Vec<u8>,
+        topic: String,
+    ) -> anyhow::Result<()> {
         // Load the guest wasm component
         let (instance, mut store) = self.engine.prepare_instance(component_id).await?;
 
         // SpinMqtt is auto generated by bindgen as per WIT files referenced above.
         let instance = SpinMqtt::new(&mut store, &instance)?;
 
         instance
-            .call_handle_message(store, &message)
+            .call_handle_message(store, &message, &mqtt_types::Metadata { topic })
             .await?
             .map_err(|err| anyhow!("failed to execute guest: {err}"))
     }
@@ -199,7 +206,11 @@ impl MqttTrigger {
                 Ok(Some(msg)) => {
                     // Handle the received message
                     _ = self
-                        .handle_mqtt_event(&component_id, msg.payload().to_vec())
+                        .handle_mqtt_event(
+                            &component_id,
+                            msg.payload().to_vec(),
+                            msg.topic().to_owned(),
+                        )
                         .await
                         .map_err(|err| tracing::error!("{err}"));
                 }

templates/mqtt-rust/content/src/lib.rs

@@ -1,8 +1,8 @@
-use spin_mqtt_sdk::{mqtt_component, Payload};
 use chrono::{DateTime, Utc};
+use spin_mqtt_sdk::{mqtt_component, Metadata, Payload};
 
 #[mqtt_component]
-fn handle_message(message: Payload) -> anyhow::Result<()> {
+async fn handle_message(message: Payload, metadata: Metadata) -> anyhow::Result<()> {
     let datetime: DateTime<Utc> = std::time::SystemTime::now().into();
     let formatted_time = datetime.format("%Y-%m-%d %H:%M:%S.%f").to_string();
 
@@ -12,4 +12,4 @@ fn handle_message(message: Payload) -> anyhow::Result<()> {
         String::from_utf8_lossy(&message)
     );
     Ok(())
-}
+}