Add gRPC Web support.

Initial implementation for supporting gRPC Web directly from
Swift gRPC services.

.gitignore

@@ -8,6 +8,7 @@ build
 /protoc-gen-swiftgrpc
 third_party/**
 /Echo
+/EchoNIO
 /test.out
 /echo.pid
 /SwiftGRPC.xcodeproj

Makefile

@@ -27,10 +27,10 @@ project-carthage:
 	@ruby fix-project-settings.rb SwiftGRPC-Carthage.xcodeproj || echo "xcodeproj ('sudo gem install xcodeproj') is required in order to generate the Carthage-compatible project!"
 	@ruby patch-carthage-project.rb SwiftGRPC-Carthage.xcodeproj || echo "xcodeproj ('sudo gem install xcodeproj') is required in order to generate the Carthage-compatible project!"
 
-test:	all
+test: all
 	swift test $(CFLAGS)
 
-test-echo:	all
+test-echo: all
 	cp .build/debug/Echo .
 	./Echo serve & /bin/echo $$! > echo.pid
 	./Echo get | tee test.out
@@ -40,6 +40,17 @@ test-echo:	all
 	kill -9 `cat echo.pid`
 	diff -u test.out Sources/Examples/Echo/test.gold
 
+test-echo-nio: all
+	cp .build/debug/EchoNIO .
+	cp .build/debug/Echo .
+	./EchoNIO serve & /bin/echo $$! > echo.pid
+	./Echo get | tee test.out
+	./Echo expand | tee -a test.out
+	./Echo collect | tee -a test.out
+	./Echo update | tee -a test.out
+	kill -9 `cat echo.pid`
+	diff -u test.out Sources/Examples/Echo/test.gold
+
 test-plugin:
 	swift build $(CFLAGS) --product protoc-gen-swiftgrpc
 	protoc Sources/Examples/Echo/echo.proto --proto_path=Sources/Examples/Echo --plugin=.build/debug/protoc-gen-swift --plugin=.build/debug/protoc-gen-swiftgrpc --swiftgrpc_out=/tmp --swiftgrpc_opt=TestStubs=true

Package.swift

@@ -23,7 +23,7 @@ var packageDependencies: [Package.Dependency] = [
   .package(url: "https://github.com/apple/swift-nio-zlib-support.git", .upToNextMinor(from: "1.0.0")),
   .package(url: "https://github.com/apple/swift-nio.git", .upToNextMinor(from: "1.12.0")),
   .package(url: "https://github.com/apple/swift-nio-nghttp2-support.git", .upToNextMinor(from: "1.0.0")),
-  .package(url: "https://github.com/apple/swift-nio-http2.git", .revision("dd9339e6310ad8537a271f3ff60a4f3976ca8e4d"))
+  .package(url: "https://github.com/apple/swift-nio-http2.git", .upToNextMinor(from: "0.2.1"))
 ]
 
 var cGRPCDependencies: [Target.Dependency] = []
@@ -75,6 +75,12 @@ let package = Package(
               "SwiftProtobuf",
               "Commander"],
             path: "Sources/Examples/Echo"),
+    .target(name: "EchoNIO",
+            dependencies: [
+              "SwiftGRPCNIO",
+              "SwiftProtobuf",
+              "Commander"],
+            path: "Sources/Examples/EchoNIO"),
     .target(name: "Simple",
             dependencies: ["SwiftGRPC", "Commander"],
             path: "Sources/Examples/Simple"),

Sources/Examples/EchoNIO/EchoProviderNIO.swift

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2018, gRPC Authors All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import Foundation
+import NIO
+import SwiftGRPCNIO
+
+class EchoProviderNIO: Echo_EchoProvider_NIO {
+  func get(request: Echo_EchoRequest, context: StatusOnlyCallContext) -> EventLoopFuture<Echo_EchoResponse> {
+    var response = Echo_EchoResponse()
+    response.text = "Swift echo get: " + request.text
+    return context.eventLoop.newSucceededFuture(result: response)
+  }
+
+  func expand(request: Echo_EchoRequest, context: StreamingResponseCallContext<Echo_EchoResponse>) -> EventLoopFuture<GRPCStatus> {
+    var endOfSendOperationQueue = context.eventLoop.newSucceededFuture(result: ())
+    let parts = request.text.components(separatedBy: " ")
+    for (i, part) in parts.enumerated() {
+      var response = Echo_EchoResponse()
+      response.text = "Swift echo expand (\(i)): \(part)"
+      endOfSendOperationQueue = endOfSendOperationQueue.then { context.sendResponse(response) }
+    }
+    return endOfSendOperationQueue.map { GRPCStatus.ok }
+  }
+
+  func collect(context: UnaryResponseCallContext<Echo_EchoResponse>) -> EventLoopFuture<(StreamEvent<Echo_EchoRequest>) -> Void> {
+    var parts: [String] = []
+    return context.eventLoop.newSucceededFuture(result: { event in
+      switch event {
+      case .message(let message):
+        parts.append(message.text)
+
+      case .end:
+        var response = Echo_EchoResponse()
+        response.text = "Swift echo collect: " + parts.joined(separator: " ")
+        context.responsePromise.succeed(result: response)
+      }
+    })
+  }
+
+  func update(context: StreamingResponseCallContext<Echo_EchoResponse>) -> EventLoopFuture<(StreamEvent<Echo_EchoRequest>) -> Void> {
+    var endOfSendOperationQueue = context.eventLoop.newSucceededFuture(result: ())
+    var count = 0
+    return context.eventLoop.newSucceededFuture(result: { event in
+      switch event {
+      case .message(let message):
+        var response = Echo_EchoResponse()
+        response.text = "Swift echo update (\(count)): \(message.text)"
+        endOfSendOperationQueue = endOfSendOperationQueue.then { context.sendResponse(response) }
+        count += 1
+
+      case .end:
+        endOfSendOperationQueue
+          .map { GRPCStatus.ok }
+          .cascade(promise: context.statusPromise)
+      }
+    })
+  }
+}

Sources/Examples/EchoNIO/Generated/echo.pb.swift

@@ -0,0 +1 @@
+../../../../Tests/SwiftGRPCNIOTests/echo.pb.swift

Sources/Examples/EchoNIO/Generated/echo_nio.grpc.swift

@@ -0,0 +1 @@
+../../../../Tests/SwiftGRPCNIOTests/echo_nio.grpc.swift

Sources/Examples/EchoNIO/Makefile

@@ -0,0 +1,11 @@
+all:
+	swift build -c debug --product EchoNIO
+	cp .build/debug/EchoNIO .
+
+project:
+	swift package generate-xcodeproj
+
+clean :
+	rm -rf Packages googleapis .build
+	rm -f Package.pins Echo google.json
+	rm -rf Package.resolved EchoNIO.xcodeproj EchoNIO

Sources/Examples/EchoNIO/README.md

@@ -0,0 +1,6 @@
+# EchoNIO, a gRPC NIO Sample App
+
+This directory contains a simple echo server that demonstrates
+all four gRPC API styles (Unary, Server Streaming, Client
+Streaming, and Bidirectional Streaming) using the NIO based
+Swift gRPC implementation.

Sources/Examples/EchoNIO/RUNME

@@ -0,0 +1,7 @@
+#!/bin/sh
+#
+# Use this to run the swift-proto generator
+#
+protoc echo.proto \
+    --swift_out=Generated \
+    --swiftgrpc_out=Client=false,Server=true,NIO=true:Generated

Sources/Examples/EchoNIO/echo.proto

@@ -0,0 +1 @@
+../Echo/echo.proto

Sources/Examples/EchoNIO/main.swift

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2018, gRPC Authors All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import Commander
+import Dispatch
+import Foundation
+import NIO
+import SwiftGRPCNIO
+
+// Common flags and options
+func addressOption(_ address: String) -> Option<String> {
+  return Option("address", default: address, description: "address of server")
+}
+
+let portOption = Option("port",
+                        default: "8080",
+                        description: "port of server")
+
+Group {
+  $0.command("serve",
+             addressOption("0.0.0.0"),
+             portOption,
+             description: "Run an echo server.") { address, port in
+    let sem = DispatchSemaphore(value: 0)
+    let eventLoopGroup = MultiThreadedEventLoopGroup(numberOfThreads: 1)
+
+    print("starting insecure server")
+    _ = try! GRPCServer.start(hostname: address,
+                          port: Int(port)!,
+                          eventLoopGroup: eventLoopGroup,
+                          serviceProviders: [EchoProviderNIO()])
+      .wait()
+
+    // This blocks to keep the main thread from finishing while the server runs,
+    // but the server never exits. Kill the process to stop it.
+    _ = sem.wait()
+  }
+
+}.run()

Sources/SwiftGRPCNIO/GRPCChannelHandler.swift

@@ -37,7 +37,7 @@ public final class GRPCChannelHandler {
 extension GRPCChannelHandler: ChannelInboundHandler {
   public typealias InboundIn = RawGRPCServerRequestPart
   public typealias OutboundOut = RawGRPCServerResponsePart
-  
+
   public func channelRead(ctx: ChannelHandlerContext, data: NIOAny) {
     let requestPart = self.unwrapInboundIn(data)
     switch requestPart {
@@ -61,9 +61,13 @@ extension GRPCChannelHandler: ChannelInboundHandler {
         assert(handlerWasRemoved)
 
         ctx.pipeline.add(handler: callHandler, after: codec).whenComplete {
-          var responseHeaders = HTTPHeaders()
-          responseHeaders.add(name: "content-type", value: "application/grpc")
-          ctx.write(self.wrapOutboundOut(.headers(responseHeaders)), promise: nil)
+          // Send the .headers event back to begin the headers flushing for the response.
+          // At this point, which headers should be returned is not known, as the content type is
+          // processed in HTTP1ToRawGRPCServerCodec. At the same time the HTTP1ToRawGRPCServerCodec
+          // handler doesn't have the data to determine whether headers should be returned, as it is
+          // this handler that checks whether the stub for the requested Service/Method is implemented.
+          // This likely signals that the architecture for these handlers could be improved.
+          ctx.write(self.wrapOutboundOut(.headers(HTTPHeaders())), promise: nil)
         }
       }
 

Sources/SwiftGRPCNIO/GRPCServer.swift

@@ -22,16 +22,11 @@ public final class GRPCServer {
 
       // Set the handlers that are applied to the accepted Channels
       .childChannelInitializer { channel in
-        //! FIXME: Add an option for gRPC-via-HTTP1 (pPRC).
-        return channel.pipeline.add(handler: HTTP2Parser(mode: .server)).then {
-          let multiplexer = HTTP2StreamMultiplexer { (channel, streamID) -> EventLoopFuture<Void> in
-            return channel.pipeline.add(handler: HTTP2ToHTTP1ServerCodec(streamID: streamID))
-              .then { channel.pipeline.add(handler: HTTP1ToRawGRPCServerCodec()) }
-              .then { channel.pipeline.add(handler: GRPCChannelHandler(servicesByName: servicesByName)) }
-          }
-
-          return channel.pipeline.add(handler: multiplexer)
-        }
+        return channel.pipeline.add(handler: HTTPProtocolSwitcher {
+          channel -> EventLoopFuture<Void> in
+          return channel.pipeline.add(handler: HTTP1ToRawGRPCServerCodec())
+            .then { channel.pipeline.add(handler: GRPCChannelHandler(servicesByName: servicesByName)) }
+        })
       }
 
       // Enable TCP_NODELAY and SO_REUSEADDR for the accepted Channels