PDF.co Web API - Barcode Reader API - VB.NET - Read Barcode From URL Asynchronously - ByteScout

PDF.co Web API – Barcode Reader API – VB.NET – Read Barcode From URL Asynchronously

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PDF.co Web API – Barcode Reader API – VB.NET – Read Barcode From URL Asynchronously

Module1.vb

[vb]
Imports System.IO
Imports System.Net
Imports System.Threading
Imports Newtonsoft.Json.Linq

‘ Cloud API asynchronous “Barcode Reader” 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 URL of source file to search barcodes in.
Const SourceFileURL As String = “https://s3-us-west-2.amazonaws.com/bytescout-com/files/demo-files/cloud-api/barcode-reader/sample.pdf”
‘ Comma-separated list of barcode types to search.
‘ See valid barcode types in the documentation https://app.pdf.co/documentation/api/1.0/barcode/read_from_url.html
Const BarcodeTypes As String = “Code128,Code39,Interleaved2of5,EAN13”
‘ Comma-separated list of page indices (or ranges) to process. Leave empty for all pages. Example: ‘0,2-5,7-‘.
Const Pages 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 `Barcode Reader` API call
Dim query As String = Uri.EscapeUriString(String.Format(
“https://api.pdf.co/v1/barcode/read/from/url?types={0}&pages={1}&url={2}&async={3}”,
BarcodeTypes,
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 with decoded barcodes 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: “InProgress”, “Failed”, “Aborted”, “Finished”.

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

If status = “Finished” Then

‘ Download generated JSON results file as string
Dim jsonFileString As String = webClient.DownloadString(resultFileUrl)

Dim jsonFoundBarcodes As JArray = JArray.Parse(jsonFileString)

‘ Display found barcodes in console
For Each token As JToken In jsonFoundBarcodes
Console.WriteLine(“Found barcode:”)
Console.WriteLine(” Type: ” + token(“TypeName”).ToString())
Console.WriteLine(” Value: ” + token(“Value”).ToString())
Console.WriteLine(” Document Page Index: ” + token(“Page”).ToString())
Console.WriteLine(” Rectangle: ” + token(“Rect”).ToString())
Console.WriteLine(” Confidence: ” + token(“Confidence”).ToString())
Console.WriteLine()
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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