feat(server): gRPC service implementation

tap_aggregator/Cargo.toml

@@ -35,7 +35,13 @@ axum = { version = "0.7.5", features = [
 futures-util = "0.3.28"
 lazy_static = "1.4.0"
 ruint = "1.10.1"
-tower = { version = "0.4", features = ["util"] }
+tower = { version = "0.4", features = ["util", "steer"] }
+tonic = { version = "0.12.3", features = ["transport"] }
+prost = "0.13.3"
+
+[build-dependencies]
+tonic-build = "0.12.3" 
+
 
 [dev-dependencies]
 jsonrpsee = { workspace = true, features = ["http-client", "jsonrpsee-core"] }

tap_aggregator/build.rs

@@ -0,0 +1,8 @@
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    println!("Running build.rs...");
+    let out_dir = std::env::var("OUT_DIR").expect("OUT_DIR not set by Cargo");
+    println!("OUT_DIR: {}", out_dir); // This should print the output directory
+
+    tonic_build::compile_protos("./proto/tap_aggregator.proto")?;
+    Ok(())
+}

tap_aggregator/proto/tap_aggregator.proto

@@ -33,7 +33,20 @@ message RavResponse {
   SignedRav rav = 1;
 }
 
+message TapRpcApiVersion {
+  string version = 1;
+}
+
+message TapRpcApiVersionsInfo {
+  repeated TapRpcApiVersion versions_supported = 1;
+  repeated TapRpcApiVersion versions_deprecated = 2;
+}
+
+// Optional request message for ApiVersions (TODO: should we use use google.protobuf.Empty?)
+message ApiVersionsRequest {}
+
 service TapAggregator {
+  rpc ApiVersions(ApiVersionsRequest) returns (TapRpcApiVersionsInfo);
   rpc AggregateReceipts(RavRequest) returns (RavResponse);
 }
 

tap_aggregator/src/server.rs

@@ -10,6 +10,7 @@ use anyhow::Result;
 use jsonrpsee::{proc_macros::rpc, server::ServerBuilder, server::ServerHandle};
 use lazy_static::lazy_static;
 use prometheus::{register_counter, register_int_counter, Counter, IntCounter};
+// use tower::steer::Steer;
 
 use crate::aggregator::check_and_aggregate_receipts;
 use crate::api_versioning::{
@@ -22,6 +23,10 @@ use tap_core::{
     rav::ReceiptAggregateVoucher, receipt::Receipt, signed_message::EIP712SignedMessage,
 };
 
+pub mod tap_aggregator {
+    tonic::include_proto!("tap_aggregator.v1");
+}
+
 // Register the metrics into the global metrics registry.
 lazy_static! {
     static ref AGGREGATION_SUCCESS_COUNTER: IntCounter = register_int_counter!(
@@ -171,6 +176,45 @@ fn aggregate_receipts_(
     }
 }
 
+use tap_aggregator::tap_aggregator_server::TapAggregator;
+use tap_aggregator::{
+    ApiVersionsRequest, RavRequest, RavResponse, SignedRav,
+    TapRpcApiVersionsInfo as TapGRpcApiVersionsInfo,
+};
+use tonic::{Request, Response, Status};
+
+#[tonic::async_trait]
+impl TapAggregator for RpcImpl {
+    async fn api_versions(
+        &self,
+        _request: Request<ApiVersionsRequest>,
+    ) -> Result<Response<TapGRpcApiVersionsInfo>, Status> {
+        // Example response
+        let response = TapGRpcApiVersionsInfo {
+            versions_deprecated: vec![],
+            versions_supported: vec![],
+        };
+
+        Ok(Response::new(response))
+    }
+
+    async fn aggregate_receipts(
+        &self,
+        request: Request<RavRequest>,
+    ) -> Result<Response<RavResponse>, Status> {
+        let rav_request = request.into_inner();
+
+        // Example implementation: create a dummy response
+        let response = RavResponse {
+            rav: Some(SignedRav {
+                message: None, // Fill this with your aggregate logic
+                signature: vec![],
+            }),
+        };
+        Ok(Response::new(response))
+    }
+}
+
 impl RpcServer for RpcImpl {
     fn api_versions(&self) -> JsonRpcResult<TapRpcApiVersionsInfo> {
         Ok(JsonRpcResponse::ok(tap_rpc_api_versions_info()))
@@ -208,6 +252,7 @@ impl RpcServer for RpcImpl {
     }
 }
 
+// TODO: create a gRPC alike run_server
 pub async fn run_server(
     port: u16,
     wallet: PrivateKeySigner,