ByteScout Cloud API Server – PDF Merging API – VB.NET – Merge PDF Documents From URLs Asynchronously

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ByteScout Cloud API Server – PDF Merging API – VB.NET – Merge PDF Documents From URLs Asynchronously

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ByteScout-Cloud-API-Server-VB-NET-Merge-PDF-Documents-From-URLs-Asynchronously.pdf

How to merge PDF documents from urls asynchronously for PDF merging API in VB.NET using ByteScout Cloud API Server

ByteScout Cloud API Server: the ready to deploy Web API Server that can be deployed in less than thirty minutes into your own in-house Windows server (no Internet connnection is required to process data!) or into private cloud server. Can store data on in-house local server based storage or in Amazon AWS S3 bucket. Processing data solely on the server using built-in ByteScout powered engine, no cloud services are used to process your data!.

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ByteScoutWebApiExample.sln

      
Microsoft Visual Studio Solution File, Format Version 12.00
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MinimumVisualStudioVersion = 10.0.40219.1
Project("{F184B08F-C81C-45F6-A57F-5ABD9991F28F}") = "ByteScoutWebApiExample", "ByteScoutWebApiExample.vbproj", "{9B91124C-66C3-4BD9-B29E-168C1ABB15AC}"
EndProject
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ByteScoutWebApiExample.vbproj

      <?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
  <PropertyGroup>
    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
    <ProjectGuid>{9B91124C-66C3-4BD9-B29E-168C1ABB15AC}</ProjectGuid>
    <OutputType>Exe</OutputType>
    <StartupObject>ByteScoutWebApiExample.Module1</StartupObject>
    <RootNamespace>ByteScoutWebApiExample</RootNamespace>
    <AssemblyName>ByteScoutWebApiExample</AssemblyName>
    <FileAlignment>512</FileAlignment>
    <MyType>Console</MyType>
    <TargetFrameworkVersion>v4.0</TargetFrameworkVersion>
  </PropertyGroup>
  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
    <PlatformTarget>AnyCPU</PlatformTarget>
    <DebugSymbols>true</DebugSymbols>
    <DebugType>full</DebugType>
    <DefineDebug>true</DefineDebug>
    <DefineTrace>true</DefineTrace>
    <OutputPath>bin\Debug\</OutputPath>
    <DocumentationFile>ByteScoutWebApiExample.xml</DocumentationFile>
    <NoWarn>42016,41999,42017,42018,42019,42032,42036,42020,42021,42022</NoWarn>
  </PropertyGroup>
  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
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    <DocumentationFile>ByteScoutWebApiExample.xml</DocumentationFile>
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  </PropertyGroup>
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  <ItemGroup>
    <Reference Include="Newtonsoft.Json, Version=10.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed, processorArchitecture=MSIL">
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    <Reference Include="System.Data" />
    <Reference Include="System.Deployment" />
    <Reference Include="System.Xml" />
    <Reference Include="System.Core" />
    <Reference Include="System.Xml.Linq" />
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    <Import Include="Microsoft.VisualBasic" />
    <Import Include="System" />
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    <Import Include="System.Diagnostics" />
    <Import Include="System.Linq" />
    <Import Include="System.Xml.Linq" />
  </ItemGroup>
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    <Compile Include="Module1.vb" />
    <Compile Include="My Project\AssemblyInfo.vb" />
    <Compile Include="My Project\Application.Designer.vb">
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      <DependentUpon>Application.myapp</DependentUpon>
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    <Compile Include="My Project\Resources.Designer.vb">
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    <Compile Include="My Project\Settings.Designer.vb">
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  <Import Project="$(MSBuildToolsPath)\Microsoft.VisualBasic.targets" />
</Project>

Module1.vb

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

' Please NOTE: In this sample we're assuming Cloud Api Server is hosted at "https://localhost". 
' If it's not then please replace this with with your hosting url.

' Cloud API asynchronous "Merge PDF" job example.
' Allows to avoid timeout errors when processing huge or scanned PDF documents.
Module Module1

 	' Direct URLs of PDF files to merge
	Dim SourceFiles As String() = {
		"https://bytescout-com.s3.amazonaws.com/files/demo-files/cloud-api/pdf-merge/sample1.pdf",
		"https://bytescout-com.s3.amazonaws.com/files/demo-files/cloud-api/pdf-merge/sample2.pdf"}
	' 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()

		' Prepare URL for `Merge PDF` API call
		Dim query As String = Uri.EscapeUriString(String.Format(
			"https://localhost/pdf/merge?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()

			Dim url As String = "https://localhost/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

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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See also:

printable version:
ByteScout-Cloud-API-Server-VB-NET-Merge-PDF-Documents-From-URLs-Asynchronously.pdf