streaming-tour

Streaming tour example

A minimal NumberService that demonstrates all four ConnectRPC RPC types in one place. The methods are deliberately trivial - the example exists to show the wire-protocol shapes (handler signatures, client invocation patterns), not to be useful.

RPC	Type	Semantics
Square	Unary	n -> n*n
Range	Server streaming	emit count consecutive integers from start
Sum	Client streaming	total all values, return when client closes its send side
RunningSum	Bidirectional streaming	after each request, emit the running total

Run it

# Terminal 1: server (listens on 127.0.0.1:8080)
cargo run -p streaming-tour-example --bin streaming-tour-server

# Terminal 2: client (calls each RPC, prints results)
cargo run -p streaming-tour-example --bin streaming-tour-client

Expected client output:

Square(7) -> 49
Range(start=10, count=5) -> [10, 11, 12, 13, 14]
Sum([3, 5, 7, 9]) -> 24
RunningSum([2, 4, 6, 8]) -> [2, 6, 12, 20]

The client connects to http://127.0.0.1:8080 by default; set TOUR_URL to point at a different address.

Integration test

tests/e2e.rs reuses the same handler implementation, spins up the server in-process on a random port, and exercises every RPC type:

cargo test -p streaming-tour-example

What to look at

• proto/anthropic/connectrpc/tour/v1/number.proto - service definition with one example of each RPC type.
• src/server.rs - handler signatures for each kind. Note how the request type changes: unary takes OwnedView<RequestView<'static>>, client/bidi take a Pin<Box<dyn Stream<Item = Result<OwnedView<...>>>>>.
• src/client.rs - generated-client invocation patterns. The client-streaming Sum takes a Vec<SumRequest>; the bidi RunningSum returns a stream you .send() to and .message() from interleaved.

Where to go next

• See examples/eliza for a real-feeling streaming app (a port of the connectrpc/examples-go ELIZA demo, with TLS, mTLS, CORS, and IPv6 support).
• See examples/middleware for tower middleware composition (custom auth layer, request tracing, timeouts) on the server side.