How to convert PDF to JPEG from URL asynchronously for PDF to image API in VB.NET with PDF.co Web API

How to convert PDF to JPEG from URL asynchronously for PDF to image API in VB.NET: Step By Step Tutorial

The coding tutorials are designed to help you test the features without need to write your own code. PDF.co Web API was made to help with PDF to image API in VB.NET. PDF.co Web API is the flexible Web API that includes full set of functions from e-signature requests to data extraction, OCR, images recognition, pdf splitting and pdf splitting. Can also generate barcodes and read barcodes from images, scans and pdf.

VB.NET code snippet like this for PDF.co Web API works best when you need to quickly implement PDF to image API in your VB.NET application. This VB.NET sample code should be copied and pasted into your project. After doing this just compile your project and click Run. Writing VB.NET application typically includes multiple stages of the software development so even if the functionality works please test it with your data and the production environment.

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Module1.vb
      
Imports System.IO Imports System.Net Imports System.Threading Imports Newtonsoft.Json.Linq ' Cloud API asynchronous "PDF To JPEG" job example. ' Allows to avoid timeout errors when processing huge or scanned PDF documents. Module Module1 ' The authentication key (API Key). ' Get your own by registering at https://app.pdf.co/documentation/api Const API_KEY As String = "***********************************" ' Source PDF file Const SourceFileUrl As String = "https://bytescout-com.s3.amazonaws.com/files/demo-files/cloud-api/pdf-to-image/sample.pdf" ' Comma-separated list of page indices (or ranges) to process. Leave empty for all pages. Example: '0,2-5,7-'. Const Pages As String = "" ' PDF document password. Leave empty for unprotected documents. Const Password As String = "" ' (!) Make asynchronous job Const Async As Boolean = True Sub Main() ' Create standard .NET web client instance Dim webClient As WebClient = New WebClient() ' Set API Key webClient.Headers.Add("x-api-key", API_KEY) ' Prepare URL for `PDF To JPEG` API call Dim query As String = Uri.EscapeUriString(String.Format( "https://api.pdf.co/v1/pdf/convert/to/jpg?password={0}&pages={1}&url={2}&async={3}", Password, Pages, SourceFileUrl, Async)) Try ' Execute request Dim response As String = webClient.DownloadString(query) ' Parse JSON response Dim json As JObject = JObject.Parse(response) If json("error").ToObject(Of Boolean) = False Then ' Asynchronous job ID Dim jobId As String = json("jobId").ToString() ' URL of generated JSON file available after the job completion; it will contain URLs of result JPEG files. Dim resultJsonFileUrl As String = json("url").ToString() ' Check the job status in a loop. ' If you don't want to pause the main thread you can rework the code ' to use a separate thread for the status checking and completion. Do Dim status As String = CheckJobStatus(jobId) ' Possible statuses: "working", "failed", "aborted", "success". ' Display timestamp and status (for demo purposes) Console.WriteLine(DateTime.Now.ToLongTimeString() + ": " + status) If status = "success" Then ' Download JSON file as string Dim jsonFileString As String = webClient.DownloadString(resultJsonFileUrl) Dim resultFilesUrls As JArray = JArray.Parse(jsonFileString) ' Download generated JPEG files Dim page As Integer = 1 For Each token As JToken In resultFilesUrls Dim resultFileUrl As String = token.ToString() Dim localFileName As String = String.Format(".\page{0}.jpg", page) webClient.DownloadFile(resultFileUrl, localFileName) Console.WriteLine("Downloaded ""{0}"".", localFileName) page = page + 1 Next Exit Do ElseIf status = "working" Then ' Pause for a few seconds Thread.Sleep(3000) Else Console.WriteLine(status) Exit Do End If Loop Else Console.WriteLine(json("message").ToString()) End If Catch ex As WebException Console.WriteLine(ex.ToString()) End Try webClient.Dispose() Console.WriteLine() Console.WriteLine("Press any key...") Console.ReadKey() End Sub Function CheckJobStatus(jobId As String) As String Using webClient As WebClient = New WebClient() ' Set API Key webClient.Headers.Add("x-api-key", API_KEY) Dim url As String = "https://api.pdf.co/v1/job/check?jobid=" + jobId Dim response As String = webClient.DownloadString(url) Dim json As JObject = JObject.Parse(response) Return Convert.ToString(json("status")) End Using End Function End Module

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packages.config
      
<?xml version="1.0" encoding="utf-8"?> <packages> <package id="Newtonsoft.Json" version="10.0.3" targetFramework="net40" /> </packages>

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ON-PREMISE OFFLINE SDK

60 Day Free Trial or Visit PDF.co Web API Home Page

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Sign Up for PDF.co Web API Online Training

ON-DEMAND REST WEB API

Get Your API Key

Explore Web API Docs

Explore Web API Samples

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