Python_Example.MD

gRPC OCR Client Example (Python)

This is a simple Python client for interacting with a gRPC OCR service. The client demonstrates how to call the OCR, health check, and documentation endpoints provided by the service.

Prerequisites

• Python 3.6+
• grpcio and grpcio-tools packages
• A running instance of the gRPC OCR service (adjust server_address if necessary)

Setup

1. Install gRPC tools

   pip install grpcio grpcio-tools googleapis-common-protos

2. Create the Proto File

   Create a new directory called protos and add your ocr_service.proto file inside it.

   syntax = "proto3";
   option csharp_namespace = "OcrGrpcWrapper";
   package ocr;
   
   service OcrService {
     rpc Process (OcrRequest) returns (OcrResponse);
     rpc HealthCheck (EchoRequest) returns (OcrResponse);
     rpc Documentation (Empty) returns (OcrResponse);
   }
   

message OcrRequest { bytes input_file = 1; string file_type = 2; string language = 3; string output_format = 4; string detect_areas_mode = 5; string allowed_characters = 6; string alphabet = 7; string ignored_characters = 8; bool auto_deskew = 9; double rotate = 10; bool upscale_small_font = 11; bool auto_contrast = 12; bool auto_denoise = 13; }

message OcrResponse {
  string output = 1;
}

message EchoRequest {
  string message = 1;
}

message Empty {}
```

3. Generate gRPC Code from Proto File

   From the directory containing the protos directory, run:

   python -m grpc_tools.protoc -I=protos --python_out=. --grpc_python_out=. protos/ocr_service.proto

   This will generate ocr_service_pb2.py and ocr_service_pb2_grpc.py files in your current directory.

4. Create the Python Client Code

   Create a new file called ocr_client.py and add the following content:

   import grpc
   import base64
   from google.protobuf.empty_pb2 import Empty
   from ocr_service_pb2 import OcrRequest, EchoRequest
   from ocr_service_pb2_grpc import OcrServiceStub
   
   def run():
       # The address of the gRPC server
       server_address = 'localhost:5000'
   
       # Path of the input image file
       image_path = 'example.png'
   
       # Read the image file as bytes
       with open(image_path, 'rb') as image_file:
           image_bytes = image_file.read()
   
       # Create a gRPC channel and a client
       channel = grpc.insecure_channel(server_address)
       client = OcrServiceStub(channel)
   
       # Create an OcrRequest message
       ocr_request = OcrRequest(
           input_file=image_bytes,
           file_type='png',
           language='eng',
           output_format='json',
           detect_areas_mode='document',
           auto_deskew=True,
           rotate=0,
           upscale_small_font=True,
           auto_contrast=True,
           auto_denoise=True,
       )
   
       # Call the Process method
       ocr_response = client.Process(ocr_request)
       print('OCR Result:')
       print(ocr_response.output)
   
       # Call the HealthCheck method
       echo_request = EchoRequest(message='Are you there?')
       health_check_response = client.HealthCheck(echo_request)
       print('Health Check Response:')
       print(health_check_response.output)
   
       # Call the Documentation method
       documentation_response = client.Documentation(Empty())
       print('Documentation Response:')
       print(documentation_response.output)
   
   if __name__ == '__main__':
       run()

5. Run the Application

   Ensure you have a valid image file named example.png in the current directory and then run:

   python ocr_client.py

Example Output

Your console should display the results of the OCR processing, along with the health check and documentation responses.

Notes

• Adjust the server_address in the code if your gRPC server is running on a different host or port.
• The input_file must be a valid image file supported by the OCR service (PNG, JPEG, BMP, or TIFF).