# Customizable Communication Channels
The `Channel` trait in our MPC engine provides a flexible and extensible abstraction for message-passing between parties. It allows communication to be implemented in various ways, enabling users to choose between platform-specific implementations. Polytune is deliberately communication-agnostic, while remaining quite flexible, offering the following features:
- **Customizable Transport**: Implement the `Channel` trait using any transport mechanism — HTTP, WebSockets, in-memory queues, or custom networking protocols.
- **Serialization-Aware**: The trait ensures that messages can be efficiently serialized.
We provide example implementations for:
- Rust sync channels using `std::sync::mpsc`
- HTTP channels for distributed deployments for servers
- WebAssembly-compatible HTTP channels for clients
- Peer-to-Peer channels
## How to Implement Your Own `Channel`
1. **Define a Struct**: Implement your own channel struct, ensuring it manages communication between multiple parties.
2. **Implement the `Channel` Trait**: Define the required methods (`send_bytes_to`, `recv_bytes_from`) based on your chosen communication mechanism.
3. **Handle Errors Gracefully**: Ensure robust error handling for message sending and receiving.
That's it! You can create a custom `Channel` implementation that integrates seamlessly with Polytune, adapting it to different transport mechanisms such as network sockets or async channels.
## Implementation Requirements
When implementing the `Channel` trait, you need to:
1. Define the error types for sending and receiving operations
2. Implement the sending mechanism through `send_bytes_to`
3. Implement the receiving mechanism through `recv_bytes_from`
```rust
trait Channel {
type SendError;
type RecvError;
async fn send_bytes_to(
&self,
p: usize,
msg: Vec<u8>,
phase: &str,
) -> Result<(), Self::SendError>;
async fn recv_bytes_from(
&self,
p: usize,
phase: &str,
) -> Result<Vec<u8>, Self::RecvError>;
}
```
## Tips for Custom Implementations
1. **Channel Parameters**:
- `p`: Index of the target party for send/receive
- `phase`: Phase of the protocol where the message is sent
- `msg`: Message sent to the target party (only in `send_bytes_to`)
2. **Connection Management**:
- Consider connection setup/teardown if needed
- Ensure proper resource cleanup
3. **Security Considerations**:
- Add encryption if transmitting over insecure channels
- Implement authentication mechanisms if needed