Add unary GET protocol support (#203)

## Summary

Implements support for Connect unary GET requests per
https://connectrpc.com/docs/protocol#unary-get-request.

By default, this behavior is disabled and can be enabled through an
option on `ProtocolClientConfig` (as demonstrated in the Eliza app).
Behavior is exercised in a new conformance test, but I do intend to add
more unit tests for this after #208.

## Linked issues

- Requires apple/swift-protobuf#1487
- Related to apple/swift-protobuf#1478
- Related to apple/swift-protobuf#1480
- Resolves #196

Connect-Swift-Mocks.podspec

@@ -13,7 +13,7 @@ Pod::Spec.new do |spec|
   spec.tvos.deployment_target = '13.0'
 
   spec.dependency 'Connect-Swift', "#{spec.version.to_s}"
-  spec.dependency 'SwiftProtobuf', '~> 1.24.0'
+  spec.dependency 'SwiftProtobuf', '~> 1.25.1'
 
   spec.source_files = 'Libraries/ConnectMocks/**/*.swift'
 

Connect-Swift.podspec

@@ -12,7 +12,7 @@ Pod::Spec.new do |spec|
   spec.osx.deployment_target = '10.15'
   spec.tvos.deployment_target = '13.0'
 
-  spec.dependency 'SwiftProtobuf', '~> 1.24.0'
+  spec.dependency 'SwiftProtobuf', '~> 1.25.1'
 
   spec.source_files = 'Libraries/Connect/**/*.swift'
 

Examples/ElizaCocoaPodsApp/Podfile.lock

@@ -1,7 +1,7 @@
 PODS:
   - Connect-Swift (0.9.0):
-    - SwiftProtobuf (~> 1.24.0)
-  - SwiftProtobuf (1.24.0)
+    - SwiftProtobuf (~> 1.25.1)
+  - SwiftProtobuf (1.25.1)
 
 DEPENDENCIES:
   - Connect-Swift (from `../..`)
@@ -15,9 +15,9 @@ EXTERNAL SOURCES:
     :path: "../.."
 
 SPEC CHECKSUMS:
-  Connect-Swift: 385477a717baf939fef2816088c329646ea9c029
-  SwiftProtobuf: bcfd2bc231cf9ae552cdc7c4e877bd3b41fe57b1
+  Connect-Swift: 0efd7a4c89656080c6510fe279d8bacaa9f95146
+  SwiftProtobuf: 69f02cd54fb03201c5e6bf8b76f687c5ef7541a3
 
 PODFILE CHECKSUM: b598f373a6ab5add976b09c2ac79029bf2200d48
 
-COCOAPODS: 1.11.3
+COCOAPODS: 1.13.0

Examples/ElizaSharedSources/AppSources/MenuView.swift

@@ -45,7 +45,8 @@ struct MenuView: View {
         let config = ProtocolClientConfig(
             host: host,
             networkProtocol: networkProtocol,
-            codec: ProtoCodec() // Protobuf binary, or JSONCodec() for JSON
+            codec: ProtoCodec(), // Protobuf binary, or JSONCodec() for JSON
+            unaryGET: .disabled // Can enable to use cacheable unary HTTP GET requests
         )
         #if !COCOAPODS
         // For gRPC (which is not supported by CocoaPods), use the NIO HTTP client:

Examples/ElizaSharedSources/GeneratedSources/connectrpc/eliza/v1/eliza.connect.swift

@@ -41,7 +41,7 @@ internal final class Connectrpc_Eliza_V1_ElizaServiceClient: Connectrpc_Eliza_V1
 
     @available(iOS 13, *)
     internal func `say`(request: Connectrpc_Eliza_V1_SayRequest, headers: Connect.Headers = [:]) async -> ResponseMessage<Connectrpc_Eliza_V1_SayResponse> {
-        return await self.client.unary(path: "/connectrpc.eliza.v1.ElizaService/Say", request: request, headers: headers)
+        return await self.client.unary(path: "/connectrpc.eliza.v1.ElizaService/Say", idempotencyLevel: .noSideEffects, request: request, headers: headers)
     }
 
     @available(iOS 13, *)

Examples/ElizaSwiftPackageApp/ElizaSwiftPackageApp.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved

@@ -50,8 +50,8 @@
       "kind" : "remoteSourceControl",
       "location" : "https://github.com/apple/swift-protobuf.git",
       "state" : {
-        "revision" : "3c54ab05249f59f2c6641dd2920b8358ea9ed127",
-        "version" : "1.24.0"
+        "revision" : "07f7f26ded8df9645c072f220378879c4642e063",
+        "version" : "1.25.1"
       }
     }
   ],

Examples/buf.gen.yaml

@@ -1,6 +1,6 @@
 version: v1
 plugins:
-  - plugin: buf.build/apple/swift:v1.24.0
+  - plugin: buf.build/apple/swift:v1.25.1
     opt: Visibility=Internal
     out: ./ElizaSharedSources/GeneratedSources
   - name: connect-swift

Libraries/Connect/Implementation/Codecs/JSONCodec.swift

@@ -18,7 +18,8 @@ import Foundation
 
 /// Codec providing functionality for serializing to/from JSON.
 public struct JSONCodec: Sendable {
-    private let encodingOptions: JSONEncodingOptions
+    private let defaultEncodingOptions: JSONEncodingOptions
+    private let deterministicEncodingOptions: JSONEncodingOptions
     private let decodingOptions: JSONDecodingOptions = {
         var options = JSONDecodingOptions()
         options.ignoreUnknownFields = true
@@ -33,10 +34,19 @@ public struct JSONCodec: Sendable {
     ///                                         defined in the `.proto` files. By default they are
     ///                                         converted to Protobuf's JSON lowerCamelCase format.
     public init(alwaysEncodeEnumsAsInts: Bool = false, preserveProtobufFieldNames: Bool = false) {
-        var encodingOptions = JSONEncodingOptions()
-        encodingOptions.alwaysPrintEnumsAsInts = alwaysEncodeEnumsAsInts
-        encodingOptions.preserveProtoFieldNames = preserveProtobufFieldNames
-        self.encodingOptions = encodingOptions
+        self.defaultEncodingOptions = {
+            var encodingOptions = JSONEncodingOptions()
+            encodingOptions.alwaysPrintEnumsAsInts = alwaysEncodeEnumsAsInts
+            encodingOptions.preserveProtoFieldNames = preserveProtobufFieldNames
+            return encodingOptions
+        }()
+        self.deterministicEncodingOptions = {
+            var encodingOptions = JSONEncodingOptions()
+            encodingOptions.useDeterministicOrdering = true
+            encodingOptions.alwaysPrintEnumsAsInts = alwaysEncodeEnumsAsInts
+            encodingOptions.preserveProtoFieldNames = preserveProtobufFieldNames
+            return encodingOptions
+        }()
     }
 }
 
@@ -46,7 +56,11 @@ extension JSONCodec: Codec {
     }
 
     public func serialize<Input: ProtobufMessage>(message: Input) throws -> Data {
-        return try message.jsonUTF8Data(options: self.encodingOptions)
+        return try message.jsonUTF8Data(options: self.defaultEncodingOptions)
+    }
+
+    public func deterministicallySerialize<Input: ProtobufMessage>(message: Input) throws -> Data {
+        return try message.jsonUTF8Data(options: self.deterministicEncodingOptions)
     }
 
     public func deserialize<Output: ProtobufMessage>(source: Data) throws -> Output {

Libraries/Connect/Implementation/Codecs/ProtoCodec.swift

@@ -13,10 +13,17 @@
 // limitations under the License.
 
 import Foundation
-import SwiftProtobuf
+// TODO: Remove `@preconcurrency` once `SwiftProtobuf.BinaryEncodingOptions` is `Sendable`
+@preconcurrency import SwiftProtobuf
 
 /// Codec providing functionality for serializing to/from Protobuf binary.
 public struct ProtoCodec {
+    private let deterministicEncodingOptions: BinaryEncodingOptions = {
+        var encodingOptions = BinaryEncodingOptions()
+        encodingOptions.useDeterministicOrdering = true
+        return encodingOptions
+    }()
+
     public init() {}
 }
 
@@ -29,6 +36,10 @@ extension ProtoCodec: Codec {
         return try message.serializedData()
     }
 
+    public func deterministicallySerialize<Input: ProtobufMessage>(message: Input) throws -> Data {
+        return try message.serializedData(options: self.deterministicEncodingOptions)
+    }
+
     public func deserialize<Output: ProtobufMessage>(source: Data) throws -> Output {
         return try Output(serializedData: source)
     }

Libraries/Connect/Implementation/Interceptors/ConnectInterceptor.swift

@@ -20,7 +20,7 @@ final class ConnectInterceptor: Interceptor {
     private let config: ProtocolClientConfig
     private let streamResponseHeaders = Locked<Headers?>(nil)
 
-    private static let protocolVersion = "1"
+    fileprivate static let protocolVersion = "1"
 
     init(config: ProtocolClientConfig) {
         self.config = config
@@ -52,12 +52,14 @@ extension ConnectInterceptor: UnaryInterceptor {
             finalRequestBody = requestBody
         }
 
-        proceed(.success(HTTPRequest(
+        proceed(.success(self.config.transformToGETIfNeeded(HTTPRequest(
             url: request.url,
             headers: headers,
             message: finalRequestBody,
-            trailers: nil
-        )))
+            method: request.method,
+            trailers: nil,
+            idempotencyLevel: request.idempotencyLevel
+        ))))
     }
 
     @Sendable
@@ -119,7 +121,9 @@ extension ConnectInterceptor: StreamInterceptor {
             url: request.url,
             headers: headers,
             message: request.message,
-            trailers: nil
+            method: request.method,
+            trailers: nil,
+            idempotencyLevel: request.idempotencyLevel
         )))
     }
 
@@ -183,3 +187,59 @@ extension ConnectInterceptor: StreamInterceptor {
         }
     }
 }
+
+private extension ProtocolClientConfig {
+    func transformToGETIfNeeded(_ request: HTTPRequest<Data?>) -> HTTPRequest<Data?> {
+        guard self.shouldUseUnaryGET(for: request) else {
+            return request
+        }
+
+        var components = URLComponents(url: request.url, resolvingAgainstBaseURL: true)
+        components?.queryItems = [
+            URLQueryItem(name: "base64", value: "1"),
+            URLQueryItem(
+                name: "compression",
+                value: request.headers[HeaderConstants.contentEncoding]?.first
+            ),
+            URLQueryItem(name: "connect", value: "v\(ConnectInterceptor.protocolVersion)"),
+            URLQueryItem(name: "encoding", value: self.codec.name()),
+            URLQueryItem(name: "message", value: request.message?.base64EncodedString()),
+        ]
+        guard let url = components?.url else {
+            return request
+        }
+
+        var headers = request.headers
+        headers.removeValue(forKey: HeaderConstants.contentEncoding)
+        headers.removeValue(forKey: HeaderConstants.contentType)
+        headers.removeValue(forKey: HeaderConstants.connectProtocolVersion)
+
+        return HTTPRequest(
+            url: url,
+            headers: headers,
+            message: nil,
+            method: .get,
+            trailers: nil,
+            idempotencyLevel: request.idempotencyLevel
+        )
+    }
+}
+
+extension ProtocolClientConfig {
+    func shouldUseUnaryGET(for request: HTTPRequest<Data?>) -> Bool {
+        guard
+            case .connect = self.networkProtocol, request.idempotencyLevel == .noSideEffects
+        else {
+            return false
+        }
+
+        switch self.unaryGET {
+        case .disabled:
+            return false
+        case .alwaysEnabled:
+            return true
+        case .enabledForLimitedPayloadSizes(let maxBytes):
+            return (request.message?.count ?? 0) <= maxBytes
+        }
+    }
+}

Libraries/Connect/Implementation/Interceptors/GRPCWebInterceptor.swift

@@ -39,7 +39,9 @@ extension GRPCWebInterceptor: UnaryInterceptor {
             url: request.url,
             headers: request.headers.addingGRPCHeaders(using: self.config, grpcWeb: true),
             message: envelopedRequestBody,
-            trailers: nil
+            method: request.method,
+            trailers: nil,
+            idempotencyLevel: request.idempotencyLevel
         )))
     }
 
@@ -125,7 +127,9 @@ extension GRPCWebInterceptor: StreamInterceptor {
             url: request.url,
             headers: request.headers.addingGRPCHeaders(using: self.config, grpcWeb: true),
             message: request.message,
-            trailers: nil
+            method: request.method,
+            trailers: nil,
+            idempotencyLevel: request.idempotencyLevel
         )))
     }
 

Libraries/Connect/Implementation/ProtocolClient.swift

@@ -40,32 +40,45 @@ extension ProtocolClient: ProtocolClientInterface {
     @discardableResult
     public func unary<Input: ProtobufMessage, Output: ProtobufMessage>(
         path: String,
+        idempotencyLevel: IdempotencyLevel,
         request: Input,
         headers: Headers,
         completion: @escaping @Sendable (ResponseMessage<Output>) -> Void
     ) -> Cancelable {
         let cancelation = Locked<(cancelable: Cancelable?, isCancelled: Bool)>((nil, false))
-        let codec = self.config.codec
+        let config = self.config
         var headers = headers
-        headers[HeaderConstants.contentType] = ["application/\(codec.name())"]
+        headers[HeaderConstants.contentType] = ["application/\(config.codec.name())"]
         let request = HTTPRequest<Input>(
-            url: URL(string: path, relativeTo: URL(string: self.config.host))!,
+            url: URL(string: path, relativeTo: URL(string: config.host))!,
             headers: headers,
             message: request,
-            trailers: nil
+            method: .post,
+            trailers: nil,
+            idempotencyLevel: idempotencyLevel
         )
         let interceptorChain = self.config.createUnaryInterceptorChain()
         interceptorChain.executeLinkedInterceptorsAndStopOnFailure(
             interceptorChain.interceptors.map { $0.handleUnaryRequest },
             firstInFirstOut: true,
             initial: request,
-            transform: { interceptedRequest, proceed in
+            transform: { intercepted, proceed in
                 do {
+                    let data: Data
+                    if config.unaryGET.isEnabled && intercepted.idempotencyLevel == .noSideEffects {
+                        data = try config.codec.deterministicallySerialize(
+                            message: intercepted.message
+                        )
+                    } else {
+                        data = try config.codec.serialize(message: intercepted.message)
+                    }
                     proceed(.success(HTTPRequest<Data?>(
-                        url: interceptedRequest.url,
-                        headers: interceptedRequest.headers,
-                        message: try codec.serialize(message: interceptedRequest.message),
-                        trailers: interceptedRequest.trailers
+                        url: intercepted.url,
+                        headers: intercepted.headers,
+                        message: data,
+                        method: intercepted.method,
+                        trailers: intercepted.trailers,
+                        idempotencyLevel: intercepted.idempotencyLevel
                     )))
                 } catch let error {
                     proceed(.failure(ConnectError(
@@ -109,7 +122,7 @@ extension ProtocolClient: ProtocolClientInterface {
                                 initial: interceptedResponse,
                                 transform: { response, proceed in
                                     proceed(ResponseMessage<Output>(
-                                        response: response, codec: codec
+                                        response: response, codec: config.codec
                                     ))
                                 },
                                 then: interceptorChain.interceptors.map { $0.handleUnaryResponse },
@@ -171,11 +184,15 @@ extension ProtocolClient: ProtocolClientInterface {
     @available(iOS 13, *)
     public func unary<Input: ProtobufMessage, Output: ProtobufMessage>(
         path: String,
+        idempotencyLevel: IdempotencyLevel,
         request: Input,
         headers: Headers
     ) async -> ResponseMessage<Output> {
         return await UnaryAsyncWrapper { completion in
-            self.unary(path: path, request: request, headers: headers, completion: completion)
+            self.unary(
+                path: path, idempotencyLevel: idempotencyLevel, request: request,
+                headers: headers, completion: completion
+            )
         }.send()
     }
 
@@ -316,7 +333,9 @@ extension ProtocolClient: ProtocolClientInterface {
             url: URL(string: path, relativeTo: URL(string: self.config.host))!,
             headers: headers,
             message: (),
-            trailers: nil
+            method: .post,
+            trailers: nil,
+            idempotencyLevel: .unknown
         )
         interceptorChain.executeInterceptorsAndStopOnFailure(
             interceptorChain.interceptors.map { $0.handleStreamStart },
@@ -330,7 +349,9 @@ extension ProtocolClient: ProtocolClientInterface {
                             url: interceptedRequest.url,
                             headers: interceptedRequest.headers,
                             message: nil, // Message is void on stream creation.
-                            trailers: interceptedRequest.trailers
+                            method: interceptedRequest.method,
+                            trailers: interceptedRequest.trailers,
+                            idempotencyLevel: interceptedRequest.idempotencyLevel
                         ),
                         responseCallbacks: responseCallbacks
                     ))