Convert Web Page To PDF From URL Asynchronously | VB.NET | HTML To PDF APIByteScout PDF SDK

Convert Web Page To PDF From URL Asynchronously | VB.NET | HTML To PDF API

Module1.vb:

VB
Imports System.IO
Imports System.Net
Imports System.Threading
Imports Newtonsoft.Json.Linq


' Cloud API asynchronous "Web Page 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 = "***********************************"

    ' URL of web page to convert to PDF document.
    Const SourceUrl As String = "http://www.usa.gov"
    ' 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 `Web Page to PDF` API call
        Dim query As String = Uri.EscapeUriString(String.Format(
            "https://api.pdf.co/v1/pdf/convert/from/url?name={0}&url={1}&async={2}",
            Path.GetFileName(DestinationFile),
            SourceUrl,
            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