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Preview PDF streamed via gRPC Pro / Enterprise

This sample demonstrates how to use Kreya's scripting capabilities to handle a gRPC streamed chunked PDF response and visualize the resulting PDF file.

Overview​

The gRPC service streams a PDF file in chunks. The script processes these chunks, assembles them into a complete PDF file, and displays it in a preview window.

gRPC Service Definition​

The following protobuf definition describes the gRPC service and the streamed response:

service PreviewService {
  rpc Pdf (google.protobuf.Empty)
    returns (stream FileChunk);
}

message FileChunk {
  bytes data = 1;
}

Script​

The following operation script listens for streamed chunks, assembles them into a PDF file, and displays the file in Kreya's preview tab:

import { writeFile, appendFile } from 'fs/promises';

const path = './preview-pdf.pdf';

// Ensure the file is empty before starting
await writeFile(path, '');

// Append each chunk of data to the file as it is received
kreya.grpc.onResponse(async msg => await appendFile(path, msg.content.data, 'base64'));

// Once the stream is complete, display the PDF in the preview tab
kreya.grpc.onCallCompleted(async () => await kreya.preview.file(path, 'PDF Preview'));

How it works​

  1. Stream initialization: The gRPC service streams chunks of the PDF file as FileChunk messages.
  2. Chunk handling: The onResponse handler processes each chunk and appends it to a local file (preview-pdf.pdf).
  3. File completion: Once the stream is complete, the onCallCompleted handler triggers and displays the assembled PDF file in Kreya's preview tab.

Output​

When the script runs, the PDF file will be displayed in Kreya's preview tab, allowing you to view the streamed content.