PDF.co Web API - PDF To Image API - VB.NET - Convert PDF To JPEG From URL Asynchronously - ByteScout

PDF.co Web API – PDF To Image API – VB.NET – Convert PDF To JPEG From URL Asynchronously

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PDF.co Web API – PDF To Image API – VB.NET – Convert PDF To JPEG From URL Asynchronously

Module1.vb

[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://s3-us-west-2.amazonaws.com/bytescout-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: “InProgress”, “Failed”, “Aborted”, “Finished”.

‘ Display timestamp and status (for demo purposes)
Console.WriteLine(DateTime.Now.ToLongTimeString() + “: ” + status)

If status = “Finished” 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 = “InProgress” 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()

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

[/vb]


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