Add possibility to send custom message (#16)

src/channels/receiver.rs

@@ -6,6 +6,8 @@ use std::{
     string::ToString,
 };
 
+use serde::Serialize;
+
 use crate::{
     cast::proxies,
     errors::Error,
@@ -253,6 +255,46 @@ where
         })
     }
 
+    ///
+    /// Sends message over chromecast message bus
+    ///
+    /// Receiver can observe messages using `context.addCustomMessageListener` with custom namespace.
+    ///
+    ///```javascript, no_run
+    /// context.addCustomMessageListener('urn:x-cast:com.example.castdata', function(customEvent) {
+    /// // do something with message
+    /// });
+    ///```
+    ///
+    /// Namespace should start with `urn:x-cast:`
+    ///
+    /// # Arguments
+    ///
+    /// * `namespace` - Message namespace that should start with `urn:x-cast:`.
+    /// * `message` - Message instance to send.
+
+    pub fn broadcast_message<M: Serialize>(
+        &self,
+        namespace: &str,
+        message: &M,
+    ) -> Result<(), Error> {
+        if !namespace.starts_with("urn:x-cast:") {
+            return Err(Error::Namespace(format!(
+                "'{}' should start with 'urn:x-cast:' prefix",
+                namespace
+            )));
+        }
+        let payload = serde_json::to_string(message)?;
+        self.message_manager.send(CastMessage {
+            namespace: namespace.to_string(),
+            source: self.sender.to_string(),
+            destination: "*".into(),
+            payload: CastMessagePayload::String(payload),
+        })?;
+
+        Ok(())
+    }
+
     /// Stops currently active app using corresponding `session_id`.
     ///
     /// # Arguments

src/errors.rs

@@ -48,6 +48,8 @@ pub enum Error {
     Serialization(SerializationError),
     /// This variant includes any error that comes from OpenSSL.
     Ssl(SslError),
+    /// Problems with given namespace
+    Namespace(String),
 }
 
 impl Display for Error {
@@ -58,6 +60,7 @@ impl Display for Error {
             Error::Protobuf(ref err) => Display::fmt(&err, f),
             Error::Serialization(ref err) => Display::fmt(&err, f),
             Error::Ssl(ref err) => Display::fmt(&err, f),
+            Error::Namespace(ref err) => Display::fmt(&err, f),
         }
     }
 }
@@ -70,6 +73,7 @@ impl StdError for Error {
             Error::Ssl(ref err) => Some(err),
             Error::Serialization(ref err) => Some(err),
             Error::Internal(_) => None,
+            Error::Namespace(_) => None,
         }
     }
 }