React Native

REST Receive Response in Chunks

See more REST Examples

Demonstrates how to receive a REST HTTP response in chunks.

Note: This example requires Chilkat 10.1.0 or greater.

React Native

import { BinData, FileAccess, Rest } from '@chilkat/react-native'

async function chilkatExample() {
  // This example requires the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  const rest = new Rest();

  // Connect to the web server
  const bTls = true;
  const port = 443;
  const bAutoReconnect = true;
  try {
    await rest.connectAsync('chilkatsoft.com', port, bTls, bAutoReconnect);
  } catch {
    console.log(rest.lastErrorText);
    return;
  }

  // Send the request.
  // This can be *any* kind of request: POST, GET, PUT, etc. using *any* of the Chilkat REST methods that send requests.
  // For this example, we'll just GET a simple XML document that is about 274K in size.

  try {
    await rest.sendReqNoBodyAsync('GET', '/hamlet.xml');
  } catch {
    console.log(rest.lastErrorText);
    return;
  }

  // Get the response header.
  const statusCode = await rest.readResponseHeaderAsync();
  if (statusCode < 0) {
    console.log(rest.lastErrorText);
    return;
  }

  console.log(`response status code = ${statusCode}`);

  const outputFile = 'c:/temp/qa_output/hamlet.xml';

  const fac = new FileAccess();
  fac.openForWrite(outputFile);
  if (statusCode < 0) {
    console.log(fac.lastErrorText);
    return;
  }

  // Get the response in chunks.
  // (Note: There are more efficient ways to simply download a file from a web server, such as by calling Chilkat's Http.Download method.
  // The purpose of this method is to show how to receive a response chunk-by-chunk.)
  const bd = new BinData();
  let status = 1;
  while (status === 1) {
    // Read a minimum of 16000 bytes.
    // Note: Because of TLS message lengths, or the possibility of the response being either compressed (gzip/deflate) or in the HTTP chunked encoding,
    // the amount of data received in each call can be greater than the specified min size.
    // Chilkat will return from the call as soon as it has received an amount equal to or more than the specified size,
    // except for the very last chunk, which can be less that the min size or even 0 bytes.

    // The status will be one of three values:
    // -1 = error
    // 0 = received the last chunk of the response.
    // 1 = received a chunk, and more chunks are coming..

    // The received data is *appended* to the contents of the BinData object.
    status = await rest.readRespChunkBdAsync(16000, bd);
    if (status >= 0) {
      console.log(`Received chunk: ${bd.numBytes} bytes`);
      fac.fileWriteBd(bd, 0, 0);
      bd.clear();
    }
  }

  fac.fileClose();

  console.log('Success.');
}