POC: Implement gRPC server as a Servlet

Author: dapengzhang0

core/src/main/java/io/grpc/internal/ServerImpl.java

@@ -59,6 +59,7 @@
 import java.util.concurrent.TimeUnit;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import javax.annotation.Nullable;
 import javax.annotation.concurrent.GuardedBy;
 
 /**
@@ -114,14 +115,16 @@ public final class ServerImpl extends io.grpc.Server implements Instrumented<Ser
   private final Channelz channelz;
   private final CallTracer serverCallTracer;
 
+  private ServerListener serverListener;
+
   /**
    * Construct a server.
    *
    * @param builder builder with configuration for server
    * @param transportServer transport server that will create new incoming transports
    * @param rootContext context that callbacks for new RPCs should be derived from
    */
-  ServerImpl(
+  public ServerImpl(
       AbstractServerImplBuilder<?> builder,
       InternalServer transportServer,
       Context rootContext) {
@@ -160,13 +163,19 @@ public ServerImpl start() throws IOException {
       checkState(!started, "Already started");
       checkState(!shutdown, "Shutting down");
       // Start and wait for any port to actually be bound.
-      transportServer.start(new ServerListenerImpl());
+      serverListener = new ServerListenerImpl();
+      transportServer.start(serverListener);
       executor = Preconditions.checkNotNull(executorPool.getObject(), "executor");
       started = true;
       return this;
     }
   }
 
+  @Nullable
+  public ServerListener getServerListener() {
+    return serverListener;
+  }
+
   @Override
   public int getPort() {
     synchronized (lock) {

examples/example-servlet/build.gradle

@@ -0,0 +1,64 @@
+description = "gRPC: Servlet example"
+buildscript {
+    repositories {
+        maven { // The google mirror is less flaky than mavenCentral()
+            url "https://maven-central.storage-download.googleapis.com/repos/central/data/" }
+
+    }
+    dependencies { classpath 'com.google.protobuf:protobuf-gradle-plugin:0.8.3' }
+}
+
+repositories {
+    maven { // The google mirror is less flaky than mavenCentral()
+        url "https://maven-central.storage-download.googleapis.com/repos/central/data/" }
+    mavenLocal()
+}
+
+apply plugin: 'war'
+
+sourceCompatibility = 1.8
+targetCompatibility = 1.8
+
+def grpcVersion = '1.15.0-SNAPSHOT' // CURRENT_GRPC_VERSION
+def protobufVersion = '3.5.1'
+def protocVersion = '3.5.1-1'
+
+dependencies {
+    compile "io.grpc:grpc-stub:${grpcVersion}"
+    compile "io.grpc:grpc-protobuf:${grpcVersion}"
+    compile "io.grpc:grpc-servlet:${grpcVersion}"
+
+    // for container that needs CDI 2
+    compile "org.jboss.weld.servlet:weld-servlet-core:3.0.4.Final"
+
+    compile ("com.google.protobuf:protobuf-java-util:${protobufVersion}") {
+        exclude group: 'com.google.guava', module: 'guava'
+    }
+
+    providedCompile group: 'javax.servlet', name: 'javax.servlet-api', version: '4.0.1'
+    // providedCompile group: 'javax.enterprise', name: 'cdi-api', version: '2.0'
+
+    // for container that needs CDI 2
+    compile group: 'javax.enterprise', name: 'cdi-api', version: '2.0'
+}
+
+apply plugin: 'com.google.protobuf'
+protobuf {
+    protoc { artifact = "com.google.protobuf:protoc:${protocVersion}" }
+    plugins { grpc { artifact = "io.grpc:protoc-gen-grpc-java:1.13.1" } }
+    generateProtoTasks {
+        all()*.plugins { grpc {} }
+    }
+}
+
+apply plugin: 'idea'
+
+// Inform IDEs like IntelliJ IDEA, Eclipse or NetBeans about the generated code.
+sourceSets {
+    main {
+        java {
+            srcDirs 'build/generated/source/proto/main/grpc'
+            srcDirs 'build/generated/source/proto/main/java'
+        }
+    }
+}

examples/example-servlet/src/main/java/io/grpc/servlet/examples/helloworld/HelloWorldServlet.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2018 The gRPC Authors
+ *
+ * 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.
+ */
+
+package io.grpc.servlet.examples.helloworld;
+
+import io.grpc.servlet.ServletAdapter;
+import java.io.IOException;
+import javax.inject.Inject;
+import javax.servlet.annotation.WebServlet;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+/**
+ * A servlet that hosts a gRPC server.
+ */
+@WebServlet(urlPatterns = {"/helloworld.Greeter/SayHello"}, asyncSupported = true)
+public class HelloWorldServlet extends HttpServlet {
+  private static final long serialVersionUID = 1L;
+
+  @Inject
+  private ServletAdapter servletAdapter;
+
+  @Override
+  protected void doGet(HttpServletRequest request, HttpServletResponse response)
+      throws IOException {
+    response.setContentType("text/html");
+    response.getWriter().println("<p>Hello World!</p>");
+  }
+
+  @Override
+  protected void doPost(HttpServletRequest request, HttpServletResponse response)
+      throws IOException {
+    if (ServletAdapter.isGrpc(request)) {
+      servletAdapter.doPost(request, response);
+    } else {
+      response.setContentType("text/html");
+      response.getWriter().println("<p>Hello non-gRPC client!</p>");
+    }
+  }
+}

examples/example-servlet/src/main/java/io/grpc/servlet/examples/helloworld/ServletAdapterProvider.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2018 The gRPC Authors
+ *
+ * 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.
+ */
+
+package io.grpc.servlet.examples.helloworld;
+
+import io.grpc.stub.StreamObserver;
+import io.grpc.examples.helloworld.GreeterGrpc;
+import io.grpc.examples.helloworld.HelloReply;
+import io.grpc.examples.helloworld.HelloRequest;
+import io.grpc.servlet.ServerBuilder;
+import io.grpc.servlet.ServletAdapter;
+import java.util.concurrent.Executors;
+import javax.enterprise.context.ApplicationScoped;
+import javax.enterprise.inject.Produces;
+
+/**
+ * A ManagedBean that produces an instance of ServletAdapter.
+ */
+@ApplicationScoped
+final class ServletAdapterProvider {
+  @Produces
+  private ServletAdapter getServletAdapter() {
+    return Provider.servletAdapter;
+  }
+
+  private static final class Provider {
+    static final ServletAdapter servletAdapter = ServletAdapter.Factory.create(
+        new ServerBuilder().addService(new GreeterImpl()));
+  }
+
+  private static final class GreeterImpl extends GreeterGrpc.GreeterImplBase {
+    GreeterImpl() {}
+
+    @Override
+    public void sayHello(HelloRequest req, StreamObserver<HelloReply> responseObserver) {
+      HelloReply reply = HelloReply.newBuilder().setMessage("Hello " + req.getName()).build();
+      responseObserver.onNext(reply);
+      responseObserver.onCompleted();
+    }
+  }
+}

examples/example-servlet/src/main/proto/helloworld/helloworld.proto

@@ -0,0 +1,37 @@
+// Copyright 2015 The gRPC Authors
+//
+// 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.
+syntax = "proto3";
+
+option java_multiple_files = true;
+option java_package = "io.grpc.examples.helloworld";
+option java_outer_classname = "HelloWorldProto";
+option objc_class_prefix = "HLW";
+
+package helloworld;
+
+// The greeting service definition.
+service Greeter {
+  // Sends a greeting
+  rpc SayHello (HelloRequest) returns (HelloReply) {}
+}
+
+// The request message containing the user's name.
+message HelloRequest {
+  string name = 1;
+}
+
+// The response message containing the greetings
+message HelloReply {
+  string message = 1;
+}

examples/example-servlet/src/main/webapp/WEB-INF/beans.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--  Jetty need this file to enable CDI -->
+<beans xmlns="http://xmlns.jcp.org/xml/ns/javaee"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/beans_2_0.xsd" bean-discovery-mode="all" version="2.0">
+  <scan></scan>
+</beans>

examples/example-servlet/src/main/webapp/WEB-INF/glassfish-web.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE glassfish-web-app PUBLIC "-//GlassFish.org//DTD GlassFish Application Server 3.1 Servlet 3.0//EN" "http://glassfish.org/dtds/glassfish-web-app_3_0-1.dtd">
+<glassfish-web-app error-url="">
+   <context-root></context-root>
+   <class-loader delegate="false"/>
+</glassfish-web-app>

servlet/build.gradle

@@ -0,0 +1,9 @@
+description = "gRPC: Servlet"
+sourceCompatibility = 1.8
+targetCompatibility = 1.8
+
+dependencies {
+    compile project(':grpc-core')
+    compileOnly group: 'javax.servlet', name: 'javax.servlet-api', version: '4.0.1'
+    compileOnly libraries.javax_annotation // java 9, 10 needs it
+}

servlet/interop-testing/build.gradle

@@ -0,0 +1,75 @@
+description = "gRPC: Servlet testing"
+buildscript {
+    repositories {
+        maven { // The google mirror is less flaky than mavenCentral()
+            url "https://maven-central.storage-download.googleapis.com/repos/central/data/" }
+
+    }
+    dependencies { classpath 'com.google.protobuf:protobuf-gradle-plugin:0.8.3' }
+}
+
+sourceCompatibility = 1.8
+targetCompatibility = 1.8
+
+def protobufVersion = '3.5.1'
+
+apply plugin: 'war'
+
+apply plugin: 'com.google.protobuf'
+protobuf {
+    protoc { artifact = "com.google.protobuf:protoc:${protocVersion}" }
+    plugins { grpc { artifact = "io.grpc:protoc-gen-grpc-java:1.13.1" } }
+    generateProtoTasks {
+        all()*.plugins { grpc {} }
+    }
+}
+
+sourceSets {
+    main {
+        java {
+            srcDirs "${rootDir}/interop-testing/src/main/java"
+            // include only the necessary source files in interop-testing
+            fileTree("${rootDir}/interop-testing/src/main/java")
+                    .exclude("io/grpc/testing/integration/Util.java")
+                    .exclude("io/grpc/testing/integration/TestServiceImpl.java")
+                    .each {
+                        exclude new File("${rootDir}/interop-testing/src/main/java").toPath()
+                                .relativize(it.toPath()).toString() }
+        }
+
+        proto { srcDirs "${rootDir}/interop-testing/src/main/proto" }
+
+        resources { srcDirs "${rootDir}/interop-testing/src/main/resources" }
+    }
+}
+
+dependencies {
+    compile project(':grpc-core')
+    compile project(':grpc-stub')
+    compile project(':grpc-protobuf')
+    compile project(':grpc-servlet')
+
+    // for container that needs CDI 2
+    compile "org.jboss.weld.servlet:weld-servlet-core:3.0.4.Final"
+
+    compile ("com.google.protobuf:protobuf-java-util:${protobufVersion}") {
+        exclude group: 'com.google.guava', module: 'guava'
+    }
+
+    providedCompile group: 'javax.servlet', name: 'javax.servlet-api', version: '4.0.1'
+    // providedCompile group: 'javax.enterprise', name: 'cdi-api', version: '2.0'
+
+    // for container that needs CDI 2
+    compile group: 'javax.enterprise', name: 'cdi-api', version: '2.0'
+
+    providedCompile "junit:junit:4.12"
+}
+
+compileJava {
+    options.compilerArgs += [
+        // Protobuf-generated code produces some warnings.
+        // https://github.com/google/protobuf/issues/2718
+        "-Xlint:-cast",
+        "-XepExcludedPaths:.*/generated/.*/java/.*",
+    ]
+}