#9 Encoders for MQTT

Signed-off-by: Subhobrata Dey <sbcd90@gmail.com>

cloudevents-sdk-paho-mqtt/README.md

@@ -0,0 +1,42 @@
+# CloudEvents SDK Rust - paho-mqtt [![Crates badge]][crates.io] [![Docs badge]][docs.rs]
+
+Integration of [CloudEvents SDK](https://github.com/cloudevents/sdk-rust/) with [paho-mqtt](https://www.eclipse.org/paho/).
+
+Look at [CloudEvents SDK README](https://github.com/cloudevents/sdk-rust/) for more info.
+
+## Development & Contributing
+
+If you're interested in contributing to sdk-rust, look at [Contributing documentation](../CONTRIBUTING.md)
+
+## Community
+
+## Sample usage
+
+- Check the example [paho-mqtt-example](../example-projects/paho-mqtt-example)
+
+### MQTT V3
+- Start the MQTT V3 Consumer
+
+```
+run --package <package-name> --bin <binary-name> -- --mode consumerV3 --broker tcp://localhost:1883 --topic test
+```
+
+- Start the MQTT V3 Producer
+
+```
+run --package <package-name> --bin <binary-name> -- --broker tcp://localhost:1883 --topic test --mode producerV3
+```
+
+### MQTT V5
+- Start the MQTT V5 Consumer
+
+```
+run --package <package-name> --bin <binary-name> -- --mode consumerV5 --broker tcp://localhost:1883 --topic test
+```
+
+- Start the MQTT V5 Producer
+
+```
+run --package <package-name> --bin <binary-name> -- --broker tcp://localhost:1883 --topic test --mode producerV5
+```
+

cloudevents-sdk-paho-mqtt/src/headers.rs

@@ -29,7 +29,6 @@ pub(crate) static CLOUDEVENTS_JSON_HEADER: &'static str = "application/cloudeven
 pub(crate) static CONTENT_TYPE: &'static str = "content-type";
 
 pub enum MqttVersion {
-    V3_1,
-    V3_1_1,
-    V5,
+    MQTT_3,
+    MQTT_5,
 }

cloudevents-sdk-paho-mqtt/src/mqtt_consumer_record.rs

@@ -5,90 +5,59 @@ use cloudevents::message::{
     Result, StructuredDeserializer, StructuredSerializer,
 };
 use cloudevents::{message, Event};
-use paho_mqtt::{Message, PropertyCode};
-use std::collections::HashMap;
+use paho_mqtt::{Message, Properties, PropertyCode};
 use std::convert::TryFrom;
-use std::str;
 
-pub struct ConsumerMessageDeserializer {
-    pub(crate) headers: HashMap<String, Vec<u8>>,
+pub struct ConsumerMessageDeserializer<'a> {
+    pub(crate) headers: &'a Properties,
     pub(crate) payload: Option<Vec<u8>>,
 }
 
-impl ConsumerMessageDeserializer {
-    fn get_mqtt_headers(message: &Message) -> Result<HashMap<String, Vec<u8>>> {
-        let mut hm = HashMap::new();
-        let prop_iterator = message.properties().iter(PropertyCode::UserProperty);
-
-        for property in prop_iterator {
-            let header = property.get_string_pair().unwrap();
-            hm.insert(header.0.to_string(), Vec::from(header.1));
-        }
-
-        Ok(hm)
+impl<'a> ConsumerMessageDeserializer<'a> {
+    fn get_mqtt_headers(message: &Message) -> &Properties {
+        message.properties()
     }
 
     pub fn new(message: &Message) -> Result<ConsumerMessageDeserializer> {
         Ok(ConsumerMessageDeserializer {
-            headers: Self::get_mqtt_headers(message)?,
+            headers: Self::get_mqtt_headers(message),
             payload: Some(message.payload()).map(|s| Vec::from(s)),
         })
     }
 }
 
-impl BinaryDeserializer for ConsumerMessageDeserializer {
-    fn deserialize_binary<R: Sized, V: BinarySerializer<R>>(mut self, mut visitor: V) -> Result<R> {
+impl<'a> BinaryDeserializer for ConsumerMessageDeserializer<'a> {
+    fn deserialize_binary<R: Sized, V: BinarySerializer<R>>(self, mut visitor: V) -> Result<R> {
         if self.encoding() != Encoding::BINARY {
             return Err(message::Error::WrongEncoding {});
         }
 
         let spec_version = SpecVersion::try_from(
-            str::from_utf8(&self.headers.remove(headers::SPEC_VERSION_HEADER).unwrap()[..])
-                .map_err(|e| cloudevents::message::Error::Other {
-                    source: Box::new(e),
-                })?,
+            self.headers
+                .find_user_property(headers::SPEC_VERSION_HEADER)
+                .unwrap()
+                .as_str(),
         )?;
 
         visitor = visitor.set_spec_version(spec_version.clone())?;
 
         let attributes = spec_version.attribute_names();
 
-        if let Some(hv) = self.headers.remove(headers::CONTENT_TYPE) {
-            visitor = visitor.set_attribute(
-                "datacontenttype",
-                MessageAttributeValue::String(String::from_utf8(hv).map_err(|e| {
-                    cloudevents::message::Error::Other {
-                        source: Box::new(e),
-                    }
-                })?),
-            )?
+        if let Some(hv) = self.headers.find_user_property(headers::CONTENT_TYPE) {
+            visitor = visitor.set_attribute("datacontenttype", MessageAttributeValue::String(hv))?
         }
 
         for (hn, hv) in self
             .headers
-            .into_iter()
+            .user_iter()
             .filter(|(hn, _)| headers::SPEC_VERSION_HEADER != *hn && hn.starts_with("ce_"))
         {
             let name = &hn["ce_".len()..];
 
             if attributes.contains(&name) {
-                visitor = visitor.set_attribute(
-                    name,
-                    MessageAttributeValue::String(String::from_utf8(hv).map_err(|e| {
-                        cloudevents::message::Error::Other {
-                            source: Box::new(e),
-                        }
-                    })?),
-                )?
+                visitor = visitor.set_attribute(name, MessageAttributeValue::String(hv))?
             } else {
-                visitor = visitor.set_extension(
-                    name,
-                    MessageAttributeValue::String(String::from_utf8(hv).map_err(|e| {
-                        cloudevents::message::Error::Other {
-                            source: Box::new(e),
-                        }
-                    })?),
-                )?
+                visitor = visitor.set_extension(name, MessageAttributeValue::String(hv))?
             }
         }
 
@@ -100,51 +69,32 @@ impl BinaryDeserializer for ConsumerMessageDeserializer {
     }
 }
 
-impl StructuredDeserializer for ConsumerMessageDeserializer {
+impl<'a> StructuredDeserializer for ConsumerMessageDeserializer<'a> {
     fn deserialize_structured<R: Sized, V: StructuredSerializer<R>>(self, visitor: V) -> Result<R> {
         visitor.set_structured_event(self.payload.unwrap())
     }
 }
 
-impl MessageDeserializer for ConsumerMessageDeserializer {
+impl<'a> MessageDeserializer for ConsumerMessageDeserializer<'a> {
     fn encoding(&self) -> Encoding {
-        match (
-            self.headers
-                .get("content-type")
-                .map(|s| String::from_utf8(s.to_vec()).ok())
-                .flatten()
-                .map(|s| s.starts_with(headers::CLOUDEVENTS_JSON_HEADER))
-                .unwrap_or(false),
-            self.headers.get(headers::SPEC_VERSION_HEADER),
-        ) {
-            (true, _) => Encoding::STRUCTURED,
-            (_, Some(_)) => Encoding::BINARY,
-            _ => Encoding::UNKNOWN,
+        match self.headers.iter(PropertyCode::UserProperty).count() == 0 {
+            true => Encoding::STRUCTURED,
+            false => Encoding::BINARY,
         }
     }
 }
 
-pub fn record_to_event(msg: &Message, version: headers::MqttVersion) -> Result<Event> {
-    match version {
-        headers::MqttVersion::V5 => {
-            BinaryDeserializer::into_event(ConsumerMessageDeserializer::new(msg)?)
-        }
-        headers::MqttVersion::V3_1 => {
-            StructuredDeserializer::into_event(ConsumerMessageDeserializer::new(msg)?)
-        }
-        headers::MqttVersion::V3_1_1 => {
-            StructuredDeserializer::into_event(ConsumerMessageDeserializer::new(msg)?)
-        }
-    }
+pub fn record_to_event(msg: &Message) -> Result<Event> {
+    MessageDeserializer::into_event(ConsumerMessageDeserializer::new(msg)?)
 }
 
 pub trait MessageExt {
-    fn to_event(&self, version: headers::MqttVersion) -> Result<Event>;
+    fn to_event(&self) -> Result<Event>;
 }
 
 impl MessageExt for Message {
-    fn to_event(&self, version: headers::MqttVersion) -> Result<Event> {
-        record_to_event(self, version)
+    fn to_event(&self) -> Result<Event> {
+        record_to_event(self)
     }
 }
 

cloudevents-sdk-paho-mqtt/src/mqtt_producer_record.rs

@@ -24,13 +24,10 @@ impl MessageRecord {
 
     pub fn from_event(event: Event, version: headers::MqttVersion) -> Result<Self> {
         match version {
-            headers::MqttVersion::V5 => {
+            headers::MqttVersion::MQTT_5 => {
                 BinaryDeserializer::deserialize_binary(event, MessageRecord::new())
             }
-            headers::MqttVersion::V3_1 => {
-                StructuredDeserializer::deserialize_structured(event, MessageRecord::new())
-            }
-            headers::MqttVersion::V3_1_1 => {
+            headers::MqttVersion::MQTT_3 => {
                 StructuredDeserializer::deserialize_structured(event, MessageRecord::new())
             }
         }
@@ -127,11 +124,14 @@ impl StructuredSerializer<MessageRecord> for MessageRecord {
 }
 
 pub trait MessageBuilderExt {
-    fn message_record(self, message_record: &MessageRecord) -> MessageBuilder;
+    fn event(self, event: Event, version: headers::MqttVersion) -> MessageBuilder;
 }
 
 impl MessageBuilderExt for MessageBuilder {
-    fn message_record(mut self, message_record: &MessageRecord) -> MessageBuilder {
+    fn event(mut self, event: Event, version: headers::MqttVersion) -> MessageBuilder {
+        let message_record =
+            MessageRecord::from_event(event, version).expect("error while serializing the event");
+
         self = self.properties(message_record.headers.clone());
 
         if let Some(s) = message_record.payload.as_ref() {