Add support to gRPC

impl/grpc/pom.xml

@@ -0,0 +1,48 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 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.serverlessworkflow</groupId>
+        <artifactId>serverlessworkflow-impl</artifactId>
+        <version>8.0.0-SNAPSHOT</version>
+    </parent>
+    <artifactId>serverlessworkflow-impl-grpc</artifactId>
+    <name>Serverless Workflow :: Impl :: gRPC</name>
+
+    <dependencies>
+        <dependency>
+            <groupId>io.serverlessworkflow</groupId>
+            <artifactId>serverlessworkflow-impl-core</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.serverlessworkflow</groupId>
+            <artifactId>serverlessworkflow-api</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.serverlessworkflow</groupId>
+            <artifactId>serverlessworkflow-impl-jackson</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>io.grpc</groupId>
+            <artifactId>grpc-stub</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.google.protobuf</groupId>
+            <artifactId>protobuf-java</artifactId>
+            <version>3.25.8</version>
+        </dependency>
+        <dependency>
+            <groupId>com.google.protobuf</groupId>
+            <artifactId>protobuf-java-util</artifactId>
+            <version>3.25.8</version>
+        </dependency>
+        <dependency>
+            <groupId>com.github.os72</groupId>
+            <artifactId>protoc-jar</artifactId>
+            <version>${version.com.github.os72.protoc.jar}</version>
+        </dependency>
+        <dependency>
+            <groupId>io.grpc</groupId>
+            <artifactId>grpc-protobuf</artifactId>
+        </dependency>
+    </dependencies>
+</project>

impl/grpc/src/main/java/io/serverlessworkflow/impl/executors/grpc/FileDescriptorContext.java

@@ -0,0 +1,21 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification 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.serverlessworkflow.impl.executors.grpc;
+
+import com.google.protobuf.DescriptorProtos;
+
+public record FileDescriptorContext(
+    DescriptorProtos.FileDescriptorSet fileDescriptorSet, String inputProto) {}

impl/grpc/src/main/java/io/serverlessworkflow/impl/executors/grpc/FileDescriptorContextSupplier.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification 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.serverlessworkflow.impl.executors.grpc;
+
+import io.serverlessworkflow.impl.TaskContext;
+import io.serverlessworkflow.impl.WorkflowContext;
+import io.serverlessworkflow.impl.WorkflowModel;
+
+@FunctionalInterface
+public interface FileDescriptorContextSupplier {
+
+  FileDescriptorContext get(
+      WorkflowContext workflowContext, TaskContext taskContext, WorkflowModel input);
+}

impl/grpc/src/main/java/io/serverlessworkflow/impl/executors/grpc/FileDescriptorReader.java

@@ -0,0 +1,109 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification 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.serverlessworkflow.impl.executors.grpc;
+
+import com.github.os72.protocjar.Protoc;
+import com.google.protobuf.DescriptorProtos;
+import io.serverlessworkflow.impl.resources.ExternalResourceHandler;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.UncheckedIOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Optional;
+
+public class FileDescriptorReader {
+
+  public FileDescriptorContext readDescriptor(ExternalResourceHandler externalResourceHandler) {
+    Path grpcDir =
+        tryCreateTempGrpcDir()
+            .orElseThrow(
+                () -> new IllegalStateException("Could not create temporary gRPC directory"));
+
+    try (InputStream inputStream = externalResourceHandler.open()) {
+
+      Path protoFile = grpcDir.resolve(externalResourceHandler.name());
+
+      Files.copy(inputStream, protoFile);
+
+      Path descriptorOutput = grpcDir.resolve("descriptor.protobin");
+
+      try {
+
+        generateFileDescriptor(grpcDir, protoFile, descriptorOutput);
+
+        DescriptorProtos.FileDescriptorSet fileDescriptorSet =
+            DescriptorProtos.FileDescriptorSet.newBuilder()
+                .mergeFrom(Files.readAllBytes(descriptorOutput))
+                .build();
+
+        return new FileDescriptorContext(fileDescriptorSet, externalResourceHandler.name());
+
+      } catch (IOException e) {
+        throw new UncheckedIOException(
+            "Unable to read external resource handler: " + externalResourceHandler.name(), e);
+      }
+    } catch (IOException e) {
+      throw new RuntimeException(e);
+    }
+  }
+
+  private Optional<Path> tryCreateTempGrpcDir() {
+    try {
+      return Optional.of(Files.createTempDirectory("serverless-workflow-"));
+    } catch (IOException e) {
+      throw new UncheckedIOException("Error while creating temporary gRPC directory", e);
+    }
+  }
+
+  /**
+   * Calls protoc binary with <code>--descriptor_set_out=</code> option set.
+   *
+   * @param grpcDir a temporary directory
+   * @param protoFile the .proto file used by <code>protoc</code> to generate the file descriptor
+   * @param descriptorOutput the output directory where the descriptor file will be generated
+   */
+  private static void generateFileDescriptor(Path grpcDir, Path protoFile, Path descriptorOutput) {
+    String[] protocArgs =
+        new String[] {
+          "--include_imports",
+          "--descriptor_set_out=" + descriptorOutput.toAbsolutePath(),
+          "-I",
+          grpcDir.toAbsolutePath().toString(),
+          protoFile.toAbsolutePath().toString()
+        };
+
+    try {
+
+      int status = Protoc.runProtoc(protocArgs);
+
+      //      TODO: I need to resolve the protoc file from PATH or from JARs, supporting all OS
+      // systems.
+      //      ProcessBuilder processBuilder = new ProcessBuilder(protocArgs);
+      //      int status = ScriptUtils.uncheckedStart(processBuilder).waitFor();
+
+      if (status != 0) {
+        throw new RuntimeException(
+            "Unable to generate file descriptor, 'protoc' execution failed with status " + status);
+      }
+    } catch (InterruptedException e) {
+      Thread.currentThread().interrupt();
+      throw new RuntimeException("Unable to generate file descriptor", e);
+    } catch (IOException e) {
+      throw new UncheckedIOException("Unable to generate file descriptor", e);
+    }
+  }
+}

impl/grpc/src/main/java/io/serverlessworkflow/impl/executors/grpc/GrpcCallExecutor.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification 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.serverlessworkflow.impl.executors.grpc;
+
+import io.serverlessworkflow.impl.TaskContext;
+import io.serverlessworkflow.impl.WorkflowContext;
+import io.serverlessworkflow.impl.WorkflowModel;
+
+@FunctionalInterface
+public interface GrpcCallExecutor {
+
+  WorkflowModel apply(
+      FileDescriptorContext fileDescriptorContext,
+      GrpcRequestContext requestContext,
+      WorkflowContext workflowContext,
+      TaskContext taskContext,
+      WorkflowModel model);
+}

impl/grpc/src/main/java/io/serverlessworkflow/impl/executors/grpc/GrpcChannelResolver.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification 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.serverlessworkflow.impl.executors.grpc;
+
+import io.grpc.Channel;
+import io.grpc.ManagedChannelBuilder;
+import io.serverlessworkflow.impl.TaskContext;
+import io.serverlessworkflow.impl.WorkflowApplication;
+import io.serverlessworkflow.impl.WorkflowContext;
+
+public class GrpcChannelResolver {
+
+  public static final String GRPC_CHANNEL_PROVIDER = "grpcChannelProvider";
+
+  public static Channel channel(
+      WorkflowContext workflowContext,
+      TaskContext taskContext,
+      GrpcRequestContext grpcRequestContext) {
+    WorkflowApplication appl = workflowContext.definition().application();
+    return appl.<Channel>additionalObject(GRPC_CHANNEL_PROVIDER, workflowContext, taskContext)
+        .orElseGet(
+            () ->
+                ManagedChannelBuilder.forAddress(
+                        grpcRequestContext.address(), grpcRequestContext.port())
+                    .usePlaintext()
+                    .build());
+  }
+}

impl/grpc/src/main/java/io/serverlessworkflow/impl/executors/grpc/GrpcExecutor.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2020-Present The Serverless Workflow Specification 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.serverlessworkflow.impl.executors.grpc;
+
+import io.serverlessworkflow.impl.TaskContext;
+import io.serverlessworkflow.impl.WorkflowContext;
+import io.serverlessworkflow.impl.WorkflowModel;
+import io.serverlessworkflow.impl.executors.CallableTask;
+import java.util.concurrent.CompletableFuture;
+
+public class GrpcExecutor implements CallableTask {
+
+  private final GrpcRequestContext requestContext;
+  private final GrpcCallExecutor grpcCallExecutor;
+  private final FileDescriptorContextSupplier fileDescriptorContextSupplier;
+
+  public GrpcExecutor(
+      GrpcRequestContext builder,
+      GrpcCallExecutor grpcCallExecutor,
+      FileDescriptorContextSupplier fileDescriptorContextSupplier) {
+    this.requestContext = builder;
+    this.grpcCallExecutor = grpcCallExecutor;
+    this.fileDescriptorContextSupplier = fileDescriptorContextSupplier;
+  }
+
+  @Override
+  public CompletableFuture<WorkflowModel> apply(
+      WorkflowContext workflowContext, TaskContext taskContext, WorkflowModel input) {
+
+    FileDescriptorContext fileDescriptorContext =
+        this.fileDescriptorContextSupplier.get(workflowContext, taskContext, input);
+
+    return CompletableFuture.supplyAsync(
+        () ->
+            this.grpcCallExecutor.apply(
+                fileDescriptorContext, requestContext, workflowContext, taskContext, input));
+  }
+}