Created
January 23, 2019 09:45
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Example of how to generate GRPC APIs from protobufs and use them in Dart.
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| // Copyright 2019 Google LLC. | |
| // SPDX-License-Identifier: Apache-2.0 | |
| // | |
| // Experiments with dart, grpc and googleapis | |
| // ========================================== | |
| // | |
| // 1. Install `protoc` | |
| // 2. `pub global activate protoc_plugin` | |
| // 3. `git clone https://github.com/googleapis/googleapis` | |
| // 4. `protoc --dart_out=grpc:lib/src/generated -I googleapis/ -I /usr/local/include/ googleapis/google/cloud/vision/v1/image_annotator.proto` | |
| // | |
| import 'package:dart_grpc_googleapis/src/generated/google/cloud/vision/v1/image_annotator.pb.dart'; | |
| import 'package:dart_grpc_googleapis/src/generated/google/cloud/vision/v1/image_annotator.pbgrpc.dart'; | |
| import 'package:path/path.dart'; | |
| import 'package:grpc/grpc.dart'; | |
| import 'dart:io'; | |
| // Assuming image.jpg and credentials.json are next the current file. | |
| var _imageFile = join(dirname(Platform.script.path), 'image.jpg'); | |
| var _serviceAccountFile = | |
| join(dirname(Platform.script.path), 'credentials.json'); | |
| void main() async { | |
| // Find the service end-point in .proto files or reference documentation. | |
| final serviceName = "vision.googleapis.com"; | |
| final port = 443; | |
| // Setup a channel | |
| var channel = ClientChannel(serviceName, | |
| port: port, | |
| options: ChannelOptions( | |
| credentials: ChannelCredentials.secure(), | |
| )); | |
| // Authenticate using credentials | |
| var auth = JwtServiceAccountAuthenticator( | |
| await File(_serviceAccountFile).readAsString()); | |
| var client = ImageAnnotatorClient(channel, options: auth.toCallOptions); | |
| // Use the generated API clients | |
| var res = await client.batchAnnotateImages(BatchAnnotateImagesRequest() | |
| ..requests.add(AnnotateImageRequest() | |
| ..image = (Image()..content = await File(_imageFile).readAsBytes()) | |
| ..features.add(Feature()..type = Feature_Type.LABEL_DETECTION))); | |
| for (var label in res.responses[0].labelAnnotations) { | |
| print(label.description); | |
| } | |
| // Close the channel | |
| await channel.shutdown(); | |
| } |
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