crates: Add serialization

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Author: patrickelectric

Cargo.toml

@@ -10,6 +10,7 @@ members = [
     "crates/generators/python",
     "crates/generators/rust",
     "crates/wasm",
+    "crates/serialization",
 ]
 
 exclude = [

crates/serialization/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "blueberry-serialization"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+cdr = "0.2.4"
+serde = { version = "1.0.228", features = ["derive"] }
+zenoh = "1.6.2"

crates/serialization/src/main.rs

@@ -0,0 +1,211 @@
+use std::error::Error;
+use std::fmt;
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::{Arc, mpsc};
+use std::thread;
+use std::time::Duration;
+
+use cdr::{CdrLe, Infinite, deserialize, serialize};
+use serde::{Deserialize, Serialize};
+use zenoh::{Config, Wait};
+
+pub type Result<T> = std::result::Result<T, SerializeError>;
+
+fn main() -> Result<()> {
+    println!("Starting serialization test");
+    zenoh::init_log_from_env_or("error");
+
+    const PUBLISH_TOPIC: &str = "blueberry/person/default";
+    const SUBSCRIBE_TOPIC: &str = "blueberry/person/expected";
+
+    let expected_person = Person::default();
+    let expected_bytes = serialize_person(&expected_person)?;
+
+    let session = zenoh::open(Config::default())
+        .wait()
+        .map_err(SerializeError::Zenoh)?;
+
+    let publisher = session
+        .declare_publisher(PUBLISH_TOPIC)
+        .wait()
+        .map_err(SerializeError::Zenoh)?;
+    let subscriber = session
+        .declare_subscriber(SUBSCRIBE_TOPIC)
+        .wait()
+        .map_err(SerializeError::Zenoh)?;
+
+    let stop = Arc::new(AtomicBool::new(false));
+    let (tx, rx) = mpsc::channel();
+
+    {
+        let stop = Arc::clone(&stop);
+        let tx = tx.clone();
+        let bytes = expected_bytes.clone();
+        thread::spawn(move || {
+            while !stop.load(Ordering::Relaxed) {
+                if let Err(err) = publisher.put(bytes.clone()).wait() {
+                    let _ = tx.send(Err(SerializeError::Zenoh(err)));
+                    stop.store(true, Ordering::Relaxed);
+                    break;
+                }
+                thread::sleep(Duration::from_secs(1));
+            }
+        });
+    }
+
+    {
+        let stop = Arc::clone(&stop);
+        let tx = tx.clone();
+        let expected = expected_person.clone();
+        thread::spawn(move || {
+            loop {
+                if stop.load(Ordering::Relaxed) {
+                    break;
+                }
+                match subscriber.recv() {
+                    Ok(sample) => {
+                        let bytes = sample.payload().to_bytes();
+                        let result = match deserialize::<Person>(&bytes) {
+                            Ok(person) => {
+                                if person == expected {
+                                    Ok(())
+                                } else {
+                                    Err(SerializeError::Mismatch(person))
+                                }
+                            }
+                            Err(err) => Err(SerializeError::Cdr(err)),
+                        };
+                        let _ = tx.send(result);
+                        stop.store(true, Ordering::Relaxed);
+                        break;
+                    }
+                    Err(err) => {
+                        let _ = tx.send(Err(SerializeError::Zenoh(err)));
+                        stop.store(true, Ordering::Relaxed);
+                        break;
+                    }
+                }
+            }
+        });
+    }
+
+    match rx.recv_timeout(Duration::from_secs(60)) {
+        Ok(Ok(())) => Ok(()),
+        Ok(Err(err)) => Err(err),
+        Err(_) => Err(SerializeError::Timeout),
+    }
+}
+
+/// Representation of the `Person` message described in the example IDL.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct Person {
+    pub name: String,
+    pub age: i32,
+    pub is_active: bool,
+    pub codename: String,
+    pub readings: [i32; 8],
+}
+
+impl Default for Person {
+    fn default() -> Self {
+        Self {
+            name: "Potato".into(),
+            age: 0x1234,
+            is_active: true,
+            codename: "maisquenada".into(),
+            readings: [0, 1, 2, 3, 4, 0xffff, 6, 7],
+        }
+    }
+}
+
+/// Serializes a `Person` using CDR little-endian encoding with an encapsulation
+/// header, honoring field alignment and boolean-as-byte rules.
+pub fn serialize_person(person: &Person) -> Result<Vec<u8>> {
+    const CODENAME_BOUND: usize = 16;
+    let codename_len = person.codename.as_bytes().len();
+    if codename_len > CODENAME_BOUND {
+        return Err(SerializeError::StringTooLong {
+            field: "codename",
+            max: CODENAME_BOUND,
+            len: codename_len,
+        });
+    }
+
+    serialize::<_, _, CdrLe>(person, Infinite).map_err(SerializeError::Cdr)
+}
+
+/// Deserializes a `Person` using CDR little-endian encoding with an encapsulation header.
+pub fn deserialize_person(bytes: &[u8]) -> Result<Person> {
+    deserialize(bytes).map_err(SerializeError::Cdr)
+}
+
+#[derive(Debug)]
+pub enum SerializeError {
+    StringTooLong {
+        field: &'static str,
+        max: usize,
+        len: usize,
+    },
+    Cdr(cdr::Error),
+    Zenoh(zenoh::Error),
+    Mismatch(Person),
+    Timeout,
+}
+
+impl fmt::Display for SerializeError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            SerializeError::StringTooLong { field, max, len } => {
+                write!(f, "string field `{field}` too long: {len} > {max}")
+            }
+            SerializeError::Cdr(err) => write!(f, "cdr serialization failed: {err}"),
+            SerializeError::Zenoh(err) => write!(f, "zenoh error: {err}"),
+            SerializeError::Mismatch(person) => {
+                write!(f, "received unexpected person payload: {person:?}")
+            }
+            SerializeError::Timeout => write!(f, "no message received within 60s"),
+        }
+    }
+}
+
+impl Error for SerializeError {}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const PERSON_DEFAULT_BYTES: [u8; 72] = [
+        0x00, 0x01, 0x00, 0x00, // CDR little-endian encapsulation header
+        0x07, 0x00, 0x00, 0x00, // name length (includes null)
+        0x50, 0x6f, 0x74, 0x61, 0x74, 0x6f, 0x00, // "Potato\0"
+        0x00, // padding to 4-byte alignment
+        0x34, 0x12, 0x00, 0x00, // age = 0x1234
+        0x01, // is_active = true (byte-encoded bool)
+        0x00, 0x00, 0x00, // padding before codename (align to 4)
+        0x0c, 0x00, 0x00, 0x00, // codename length (includes null)
+        0x6d, 0x61, 0x69, 0x73, 0x71, 0x75, 0x65, 0x6e, 0x61, 0x64, 0x61,
+        0x00, // "maisquenada\0"
+        0x00, 0x00, 0x00, 0x00, // readings[0] = 0
+        0x01, 0x00, 0x00, 0x00, // readings[1] = 1
+        0x02, 0x00, 0x00, 0x00, // readings[2] = 2
+        0x03, 0x00, 0x00, 0x00, // readings[3] = 3
+        0x04, 0x00, 0x00, 0x00, // readings[4] = 4
+        0xff, 0xff, 0x00, 0x00, // readings[5] = 0xffff
+        0x06, 0x00, 0x00, 0x00, // readings[6] = 6
+        0x07, 0x00, 0x00, 0x00, // readings[7] = 7
+    ];
+
+    #[test]
+    fn serializes_default_person() {
+        let bytes = serialize_person(&Person::default()).expect("serialize default person");
+        assert_eq!(bytes, PERSON_DEFAULT_BYTES);
+    }
+
+    #[test]
+    fn rejects_codename_overflow() {
+        let mut person = Person::default();
+        person.codename = "this-is-way-too-long".into();
+        let err = serialize_person(&person).unwrap_err();
+        assert!(matches!(err, SerializeError::StringTooLong { .. }));
+    }
+}