feat(transport): Add service multiplexing/routing (#99)

* feat(transport): Add service multiplexing/routing

This change introduces a new "router" built on top of
`transport::Server` that allows one to run multiple
gRPC services on the same socket.

```rust
Server::builder()
    .add_service(greeter)
    .add_service(echo)
    .serve(addr)
    .await?;
```

There is also a new `multiplex` example showcasing
server side service multiplexing and client side
service multiplexing.

BREAKING CHANGES: `Server::serve` is now crate private
and all services must be added via `Server::add_service`.
Codegen also returns just a `Service` now instead of a
`MakeService` pair.

Closes #29

Signed-off-by: Lucio Franco [email protected]

tonic-examples/src/authentication/server.rs

@@ -78,8 +78,8 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
                 }
             }
         })
-        .clone()
-        .serve(addr, pb::server::EchoServer::new(server))
+        .add_service(pb::server::EchoServer::new(server))
+        .serve(addr)
         .await?;
 
     Ok(())

tonic-examples/src/helloworld/server.rs

@@ -33,7 +33,8 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let greeter = MyGreeter::default();
 
     Server::builder()
-        .serve(addr, GreeterServer::new(greeter))
+        .add_service(GreeterServer::new(greeter))
+        .serve(addr)
         .await?;
 
     Ok(())

tonic-examples/src/load_balance/server.rs

@@ -60,7 +60,9 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
         let mut tx = tx.clone();
 
         let server = EchoServer { addr };
-        let serve = Server::builder().serve(addr, pb::server::EchoServer::new(server));
+        let serve = Server::builder()
+            .add_service(pb::server::EchoServer::new(server))
+            .serve(addr);
 
         tokio::spawn(async move {
             if let Err(e) = serve.await {

tonic-examples/src/multiplex/client.rs

@@ -0,0 +1,37 @@
+pub mod hello_world {
+    tonic::include_proto!("helloworld");
+}
+
+pub mod echo {
+    tonic::include_proto!("grpc.examples.echo");
+}
+
+use echo::{client::EchoClient, EchoRequest};
+use hello_world::{client::GreeterClient, HelloRequest};
+use tonic::transport::Endpoint;
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let channel = Endpoint::from_static("http://[::1]:50051").channel();
+
+    let mut greeter_client = GreeterClient::new(channel.clone());
+    let mut echo_client = EchoClient::new(channel);
+
+    let request = tonic::Request::new(HelloRequest {
+        name: "Tonic".into(),
+    });
+
+    let response = greeter_client.say_hello(request).await?;
+
+    println!("GREETER RESPONSE={:?}", response);
+
+    let request = tonic::Request::new(EchoRequest {
+        message: "hello".into(),
+    });
+
+    let response = echo_client.unary_echo(request).await?;
+
+    println!("ECHO RESPONSE={:?}", response);
+
+    Ok(())
+}

tonic-examples/src/multiplex/server.rs

@@ -0,0 +1,69 @@
+use std::collections::VecDeque;
+use tonic::{transport::Server, Request, Response, Status};
+
+pub mod hello_world {
+    tonic::include_proto!("helloworld");
+}
+
+pub mod echo {
+    tonic::include_proto!("grpc.examples.echo");
+}
+
+use hello_world::{
+    server::{Greeter, GreeterServer},
+    HelloReply, HelloRequest,
+};
+
+use echo::{
+    server::{Echo, EchoServer},
+    EchoRequest, EchoResponse,
+};
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let addr = "[::1]:50051".parse().unwrap();
+
+    let greeter = GreeterServer::new(MyGreeter::default());
+    let echo = EchoServer::new(MyEcho::default());
+
+    Server::builder()
+        .add_service(greeter)
+        .add_service(echo)
+        .serve(addr)
+        .await?;
+
+    Ok(())
+}
+
+#[derive(Default)]
+pub struct MyGreeter {}
+
+#[tonic::async_trait]
+impl Greeter for MyGreeter {
+    async fn say_hello(
+        &self,
+        request: Request<HelloRequest>,
+    ) -> Result<Response<HelloReply>, Status> {
+        let reply = hello_world::HelloReply {
+            message: format!("Hello {}!", request.into_inner().name).into(),
+        };
+        Ok(Response::new(reply))
+    }
+}
+
+#[derive(Default)]
+pub struct MyEcho;
+
+#[tonic::async_trait]
+impl Echo for MyEcho {
+    async fn unary_echo(
+        &self,
+        request: Request<EchoRequest>,
+    ) -> Result<Response<EchoResponse>, Status> {
+        let message = request.into_inner().message;
+        Ok(Response::new(EchoResponse { message }))
+    }
+
+    type ServerStreamingEchoStream = VecDeque<Result<EchoResponse, Status>>;
+    type BidirectionalStreamingEchoStream = VecDeque<Result<EchoResponse, Status>>;
+}

tonic-examples/src/routeguide/server.rs

@@ -155,7 +155,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 
     let svc = server::RouteGuideServer::new(route_guide);
 
-    Server::builder().serve(addr, svc).await?;
+    Server::builder().add_service(svc).serve(addr).await?;
 
     Ok(())
 }

tonic-examples/src/tls/server.rs

@@ -61,7 +61,8 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
     Server::builder()
         .tls_config(ServerTlsConfig::with_rustls().identity(identity))
         .clone()
-        .serve(addr, pb::server::EchoServer::new(server))
+        .add_service(pb::server::EchoServer::new(server))
+        .serve(addr)
         .await?;
 
     Ok(())

tonic-examples/src/tls_client_auth/client.rs

@@ -13,7 +13,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
     let client_key = tokio::fs::read("tonic-examples/data/tls/client1.key").await?;
     let client_identity = Identity::from_pem(client_cert, client_key);
 
-    let tls = ClientTlsConfig::with_openssl()
+    let tls = ClientTlsConfig::with_rustls()
         .domain_name("localhost")
         .ca_certificate(server_root_ca_cert)
         .identity(client_identity)

tonic-examples/src/tls_client_auth/server.rs

@@ -44,8 +44,8 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 
     Server::builder()
         .tls_config(&tls)
-        .clone()
-        .serve(addr, pb::server::EchoServer::new(server))
+        .add_service(pb::server::EchoServer::new(server))
+        .serve(addr)
         .await?;
 
     Ok(())