How to convert images to PDF from urls asynchronously for image to PDF API in VB.NET and PDF.co Web API

How to convert images to PDF from urls asynchronously in VB.NET with easy ByteScout code samples to make image to PDF API. Step-by-step tutorial

Every ByteScout tool contains example VB.NET source codes that you can find here or in the folder with installed ByteScout product. PDF.co Web API was made to help with image to PDF API in VB.NET. PDF.co Web API is the Web API with a set of tools for documents manipulation, data conversion, data extraction, splitting and merging of documents. Includes image recognition, built-in OCR, barcode generation and barcode decoders to decode bar codes from scans, pictures and pdf.

The SDK samples like this one below explain how to quickly make your application do image to PDF API in VB.NET with the help of PDF.co Web API. For implimentation of this functionality, please copy and paste code below into your app using code editor. Then compile and run your app. Enjoy writing a code with ready-to-use sample VB.NET codes to add image to PDF API functions using PDF.co Web API in VB.NET.

Trial version of ByteScout is available for free download from our website. This and other source code samples for VB.NET and other programming languages are available.

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Module1.vb
      
Imports System.IO Imports System.Net Imports System.Threading Imports Newtonsoft.Json.Linq ' Cloud API asynchronous "Image To PDF" 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 = "***********************************" ' Direct URLs of image files to convert to PDF document Dim SourceFiles As String() = { "https://bytescout-com.s3.amazonaws.com/files/demo-files/cloud-api/image-to-pdf/image1.png", "https://bytescout-com.s3.amazonaws.com/files/demo-files/cloud-api/image-to-pdf/image2.jpg"} ' Destination PDF file name Const DestinationFile As String = ".\result.pdf" ' (!) 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 `Image To PDF` API call Dim query As String = Uri.EscapeUriString(String.Format( "https://api.pdf.co/v1/pdf/convert/from/image?name={0}&url={1}&async={2}", Path.GetFileName(DestinationFile), String.Join(",", SourceFiles), 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 PDF file that will available after the job completion Dim resultFileUrl 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 PDF file webClient.DownloadFile(resultFileUrl, DestinationFile) Console.WriteLine("Generated PDF file saved as ""{0}"" file.", DestinationFile) 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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