How to Convert Documents to PDF by Using Visual Basic

In this tutorial we will cover how to implement asynchronous approach of Document Conversion Suite. You only need to send source document to SubmitTIFFConversionTask or SubmitPDFConversionTask API methods to receive task identifier as response. There is also SubmitDOCXConversionTask method to convert PDF documents to editable Microsoft Word document.

After receiving task identifier you need to check task status by calling GetConversionTaskStatus method. You need to call same method after a few seconds delay as long as task status equals to “Waiting”. Once you receive “Completed” from GetConversionTaskStatus method you can call DownloadResult method to download final document file. You can use the Visual Basic implementation below.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
Imports System
Imports System.IO
Imports System.Net.Http

Module Program
    Async Function SubmitPdfConversionTask(filePathToConvert As String, rapidApiKey As String) As Task(Of String)
        Using httpClient As New HttpClient()
            Using form As New MultipartFormDataContent()
                form.Headers.Add("X-RapidAPI-Key", rapidApiKey)
                form.Add(New StringContent("Sebastian"), "authorName")
                form.Add(New StringContent("Final report"), "title")
                form.Add(New StringContent("Reports, Final"), "keywords")
                form.Add(New StringContent("Quarterly Final Report"), "name")
								
                Dim fileBytes = Await File.ReadAllBytesAsync(filePathToConvert)
                Dim fileName = Path.GetFileName(filePathToConvert)
                form.Add(New ByteArrayContent(fileBytes, 0, fileBytes.Length), "file", fileName)

                Using response = Await httpClient.PostAsync("https://petadata-document-conversion-suite.p.rapidapi.com/SubmitPDFConversionTask", form)
                    response.EnsureSuccessStatusCode()
                    Return Await response.Content.ReadAsStringAsync()
                End Using
            End Using
        End Using
    End Function
		
    Async Function GetConversionTaskStatus(taskId As String, rapidApiKey As String) As Task(Of String)
        Using httpClient As New HttpClient()
            httpClient.DefaultRequestHeaders.Add("X-RapidAPI-Key", rapidApiKey)
            Using response = Await httpClient.GetAsync($"https://petadata-document-conversion-suite.p.rapidapi.com/GetConversionTaskStatus?taskId={taskId}")
                response.EnsureSuccessStatusCode()
                Return Await response.Content.ReadAsStringAsync()
            End Using
        End Using
    End Function
		
    Async Function DownloadResult(taskId As String, rapidApiKey As String) As Task(Of Byte())
        Using httpClient As New HttpClient()
            httpClient.DefaultRequestHeaders.Add("X-RapidAPI-Key", rapidApiKey)
            Using response = Await httpClient.GetAsync($"https://petadata-document-conversion-suite.p.rapidapi.com/DownloadResult?taskId={taskId}")
                response.EnsureSuccessStatusCode()
                Return Await response.Content.ReadAsByteArrayAsync()
            End Using
        End Using
    End Function
		
    Public Async Function ConvertDocumentAsync() As Task
        Dim rapidApiKey = "<YOUR RAPIDAPI KEY HERE>"
        Dim filePathToConvert = "<FILE PATH TO CONVERT>"
        Dim taskId = Await SubmitPdfConversionTask(filePathToConvert, rapidApiKey)
        Dim retryCount = 0
        Do While (retryCount < 100)
            retryCount += 1
            Await Task.Delay(5000)
            Dim status = Await GetConversionTaskStatus(taskId, rapidApiKey)
            If (status = "Completed") Then
                Dim fileBytes = Await DownloadResult(taskId, rapidApiKey)
                Await File.WriteAllBytesAsync("final_report.pdf", fileBytes)
                Exit Do
            ElseIf (status = "Waiting") Then
                Continue Do
            ElseIf (status = "Failed") Then
                Throw New Exception("Cannot convert file")
            Else
                Throw New Exception("Invalid status")
            End If
        Loop
    End Function
		
    Sub Main(args As String())
        ConvertDocumentAsync().Wait()
    End Sub
End Module