CS_Example.MD

gRPC OCR Client Example

This is a simple C# 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

• .NET 7.0 SDK or newer.
• A running instance of the gRPC OCR service / Docker (adjust serverAddress if necessary)

Setup

1. Create a New Console Application

   dotnet new console -o OcrClientApp
   cd OcrClientApp

2. Add gRPC and Protobuf NuGet Packages

   dotnet add package Grpc.Net.Client
   dotnet add package Google.Protobuf
   dotnet add package Grpc.Tools

3. Add the OcrClient.cs File

   Create a new file called OcrClient.cs and add the following content:

   using System;
   using System.IO;
   using System.Threading.Tasks;
   using Google.Protobuf;
   using Grpc.Net.Client;
   using OcrGrpcWrapper;
   
   class Program
   {
       static async Task Main(string[] args)
       {
           // The address of the gRPC server
           string serverAddress = "http://localhost:5000";
   
           // Path of the input image file
           string imagePath = "example.png";
   
           // Read image file as byte array
           byte[] imageBytes = await File.ReadAllBytesAsync(imagePath);
   
           // Create a channel and a client
           using var channel = GrpcChannel.ForAddress(serverAddress);
           var client = new OcrService.OcrServiceClient(channel);
   
           // Create an OcrRequest message
           var request = new OcrRequest
           {
               InputFile = ByteString.CopyFrom(imageBytes),
               Language = "eng",
               OutputFormat = "json",
               DetectAreasMode = "document",
               AutoDeskew = true,
               Rotate = 0,
               UpscaleSmallFont = true,
               AutoContrast = true,
               AutoDenoise = true
           };
   
           // Call the Process method
           OcrResponse response = await client.ProcessAsync(request);
   
           // Display the result
           Console.WriteLine("OCR Result:");
           Console.WriteLine(response.Output);
   
           // Call the HealthCheck method
           var healthCheckRequest = new EchoRequest { Message = "Are you there?" };
           OcrResponse healthCheckResponse = await client.HealthCheckAsync(healthCheckRequest);
   
           // Display the health check response
           Console.WriteLine("Health Check Response:");
           Console.WriteLine(healthCheckResponse.Output);
   
           // Call the Documentation method
           OcrResponse documentationResponse = await client.DocumentationAsync(new Empty());
   
           // Display the documentation response
           Console.WriteLine("Documentation Response:");
           Console.WriteLine(documentationResponse.Output);
       }
   }

4. Add the Proto File

   Create a new directory called Protos and add your ocr_service.proto file in it. Ensure it is included in your project file as follows:

   <ItemGroup>
     <Protobuf Include="Protos\ocr_service.proto" GrpcServices="Client" />
   </ItemGroup>

5. Run the Application

   Ensure that you have a valid image file named example.png in the project directory.

   dotnet run

Example Output

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

Notes

• Adjust the serverAddress 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).