New MP gRPC end-to-end example that uses gRPC proxy-based API

examples/microprofile/grpc/README.md

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+# Helidon gRPC MP Example
+
+This examples shows a simple application written using Helidon gRPC MP API:
+
+- StringService: a gRPC service implementation that uses MP
+- StringServiceClient: an interface from which a client proxy can be created to call StringService remote methods
+- StringServiceTest: a sample test that starts a server and tests the client and server components
+- application.yaml: configuration for server and client channels
+
+## Build and run
+
+```shell
+mvn package
+java -jar target/helidon-examples-microprofile-grpc.jar 
+```

examples/microprofile/grpc/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+    Copyright (c) 2024 Oracle and/or its affiliates.
+
+    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.
+
+-->
+<project xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xmlns="http://maven.apache.org/POM/4.0.0"
+        xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>io.helidon.applications</groupId>
+        <artifactId>helidon-mp</artifactId>
+        <version>4.1.0-SNAPSHOT</version>
+        <relativePath/>
+    </parent>
+    <groupId>io.helidon.examples.microprofile</groupId>
+    <artifactId>helidon-examples-microprofile-grpc</artifactId>
+    <name>Helidon Examples Microprofile gRPC</name>
+
+    <description>
+        Microprofile example that uses gRPC
+    </description>
+
+    <dependencies>
+        <dependency>
+            <groupId>io.helidon.grpc</groupId>
+            <artifactId>helidon-grpc-core</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.helidon.microprofile.grpc</groupId>
+            <artifactId>helidon-microprofile-grpc-core</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.helidon.microprofile.grpc</groupId>
+            <artifactId>helidon-microprofile-grpc-server</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.helidon.microprofile.grpc</groupId>
+            <artifactId>helidon-microprofile-grpc-client</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.helidon.microprofile.testing</groupId>
+            <artifactId>helidon-microprofile-testing-junit5</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.helidon.webserver.testing.junit5</groupId>
+            <artifactId>helidon-webserver-testing-junit5-grpc</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.helidon.logging</groupId>
+            <artifactId>helidon-logging-jul</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+        <dependency>
+            <!--
+            Need to use this version to work around the same groupId/artifactId and
+            different package names in Jakarta. This is needed for the Generated annotation.
+            -->
+            <groupId>javax.annotation</groupId>
+            <artifactId>javax.annotation-api</artifactId>
+            <scope>provided</scope>
+            <optional>true</optional>
+        </dependency>
+
+    </dependencies>
+
+    <build>
+        <extensions>
+            <extension>
+                <groupId>kr.motd.maven</groupId>
+                <artifactId>os-maven-plugin</artifactId>
+                <version>${version.plugin.os}</version>
+            </extension>
+        </extensions>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-dependency-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <id>copy-libs</id>
+                    </execution>
+                </executions>
+            </plugin>
+            <plugin>
+                <groupId>org.xolstice.maven.plugins</groupId>
+                <artifactId>protobuf-maven-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>compile</goal>
+                            <goal>test-compile</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+</project>

examples/microprofile/grpc/src/main/java/io/helidon/examples/microprofile/grpc/StringService.java

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+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * 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.helidon.examples.microprofile.grpc;
+
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import io.helidon.grpc.api.Grpc;
+import io.helidon.grpc.core.CollectingObserver;
+
+import io.grpc.stub.StreamObserver;
+import jakarta.enterprise.context.ApplicationScoped;
+
+/**
+ * An implementation of a string service.
+ */
+@Grpc.GrpcService
+@ApplicationScoped
+public class StringService {
+
+    /**
+     * Uppercase a string.
+     *
+     * @param request string message
+     * @return string message
+     */
+    @Grpc.Unary("Upper")
+    public Strings.StringMessage upper(Strings.StringMessage request) {
+        return newMessage(request.getText().toUpperCase());
+    }
+
+    /**
+     * Lowercase a string.
+     *
+     * @param request string message
+     * @return string message
+     */
+    @Grpc.Unary("Lower")
+    public Strings.StringMessage lower(Strings.StringMessage request) {
+        return newMessage(request.getText().toLowerCase());
+    }
+
+    /**
+     * Split a string using space delimiters.
+     *
+     * @param request string message
+     * @return stream of string messages
+     */
+    @Grpc.ServerStreaming("Split")
+    public Stream<Strings.StringMessage> split(Strings.StringMessage request) {
+        String[] parts = request.getText().split(" ");
+        return Stream.of(parts).map(this::newMessage);
+    }
+
+    /**
+     * Join a stream of messages using spaces.
+     *
+     * @param observer stream of messages
+     * @return single message as a stream
+     */
+    @Grpc.ClientStreaming("Join")
+    public StreamObserver<Strings.StringMessage> join(StreamObserver<Strings.StringMessage> observer) {
+        return CollectingObserver.create(
+                Collectors.joining(" "),
+                observer,
+                Strings.StringMessage::getText,
+                this::newMessage);
+    }
+
+    private Strings.StringMessage newMessage(String text) {
+        return Strings.StringMessage.newBuilder().setText(text).build();
+    }
+}
+

examples/microprofile/grpc/src/main/java/io/helidon/examples/microprofile/grpc/StringServiceClient.java

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+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * 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.helidon.examples.microprofile.grpc;
+
+import java.util.stream.Stream;
+
+import io.helidon.grpc.api.Grpc;
+
+import io.grpc.stub.StreamObserver;
+
+/**
+ * A client for a {@link StringService}.
+ */
+@Grpc.GrpcService("StringService")
+@Grpc.GrpcChannel("string-channel")         // see application.yaml
+public interface StringServiceClient {
+
+    /**
+     * Uppercase a string.
+     *
+     * @param request string message
+     * @return string message
+     */
+    @Grpc.Unary("Upper")
+    Strings.StringMessage upper(Strings.StringMessage request);
+
+    /**
+     * Lowercase a string.
+     *
+     * @param request string message
+     * @return string message
+     */
+    @Grpc.Unary("Lower")
+    Strings.StringMessage lower(Strings.StringMessage request);
+
+    /**
+     * Split a string using space delimiters.
+     *
+     * @param request string message
+     * @return stream of string messages
+     */
+    @Grpc.ServerStreaming("Split")
+    Stream<Strings.StringMessage> split(Strings.StringMessage request);
+
+    /**
+     * Join a stream of messages using spaces.
+     *
+     * @param observer stream of messages
+     * @return single message as a stream
+     */
+    @Grpc.ClientStreaming("Join")
+    StreamObserver<Strings.StringMessage> join(StreamObserver<Strings.StringMessage> observer);
+}
+

examples/microprofile/grpc/src/main/java/io/helidon/examples/microprofile/grpc/package-info.java

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+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * 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.helidon.examples.microprofile.grpc;

examples/microprofile/grpc/src/main/proto/strings.proto

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+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * 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_package = "io.helidon.examples.microprofile.grpc";
+
+service StringService {
+  rpc Upper (StringMessage) returns (StringMessage) {}
+  rpc Lower (StringMessage) returns (StringMessage) {}
+  rpc Split (StringMessage) returns (stream StringMessage) {}
+  rpc Join (stream StringMessage) returns (StringMessage) {}
+}
+
+message StringMessage {
+  string text = 1;
+}

examples/microprofile/grpc/src/main/resources/META-INF/beans.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+
+    Copyright (c) 2024 Oracle and/or its affiliates.
+
+    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.
+
+-->
+<beans xmlns="https://jakarta.ee/xml/ns/jakartaee"
+       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+       xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee
+                           https://jakarta.ee/xml/ns/jakartaee/beans_3_0.xsd"
+       version="3.0"
+       bean-discovery-mode="annotated">
+</beans>