How to render reports asynchronously by using the async and await keywords
Environment
| Product | Progress® Telerik® Reporting |
| Framework | .NET Framework 4.5 and higher |
Description
With the new .NET Framework (4.5), a new way to handle parallel programming has been added - with the help of the Task<> class and the keywords async and await, parallel programming has become much easier. This raises the question, how can these features be used with Telerik Reporting?
Solution
First, we will have to start with the ReportProcessor class and its RenderReport method, which provides all the needed functionality for programmatic generation of reports. Since RenderReport returns RenderingResult, in order to use it asynchronously, you will have to create a method that returns this result. However, since we want to achieve the task in an async manner, we will take advantage of the Task class:
public class AsyncWrappers
{
// Wrap the RenderingResult like this:
public async Task<RenderingResult> RenderReportAsync(Type reportType) // Pass parameters here, like device info and report to render
{
ReportProcessor reportProcessor = new ReportProcessor();
// Apply any deviceInfo settings if necessary
Hashtable deviceInfo = new Hashtable();
// Any other Report Source can be used instead
// For example InstanceReportSource can be used if the instantiated report is passed as parameter of the method
TypeReportSource typeReportSource = new TypeReportSource();
typeReportSource.TypeName = reportType.AssemblyQualifiedName;
return await Task.Run(() => reportProcessor.RenderReport("PDF", typeReportSource, deviceInfo));
}
}
Public Class AsyncWrappers
' Wrap the RenderingResult like this:
Public Function RenderReportAsync(reportType As Type) As Task(Of RenderingResult)
' Pass parameters here, like device info and report to render
Dim reportProcessor As New ReportProcessor()
' Apply any deviceInfo settings if necessary
Dim deviceInfo As New Hashtable()
' Any other Report Source can be used instead
' For example InstanceReportSource can be used if the instantiated report is passed as parameter of the method
Dim typeReportSource As New TypeReportSource()
typeReportSource.TypeName = reportType.AssemblyQualifiedName
Return Await Task.Run(Function() reportProcessor.RenderReport("PDF", typeReportSource, deviceInfo))
End Function
End Class
Besides declaring the return value to be Task<RenderingResult> we have marked the method as async. Also, we are invoking the RenderReport method using the await keyword. For the second part, we will use our method in an async manner:
//Use the wrapper in your code like this:
public async Task<string> RenderReportAsync()
{
var asyncWrappers = new AsyncWrappers();
Console.WriteLine("Rendering started on: {0}", Thread.CurrentThread.ManagedThreadId);
var result = await asyncWrappers.RenderReportAsync( typeof(Telerik.Reporting.Report) );// pass the type of your report here
string fileName = result.DocumentName + "." + result.Extension;
string path = System.IO.Path.GetTempPath();
string filePath = System.IO.Path.Combine(path, fileName);
using (System.IO.FileStream fs = new System.IO.FileStream(filePath, System.IO.FileMode.Create))
{
fs.Write(result.DocumentBytes, 0, result.DocumentBytes.Length);
}
Console.WriteLine("Rendering finished on: {0}\n", Thread.CurrentThread.ManagedThreadId);
// You can return void but that is not recommended
return string.Format("Successfully rendered! File saved in {0}\n", filePath);
}
'Use the wrapper in your code like this:
Public Function RenderReportAsync() As Task(Of String)
Dim asyncWrappers = New AsyncWrappers()
Console.WriteLine("Rendering started on: {0}", Thread.CurrentThread.ManagedThreadId)
Dim result = Await asyncWrappers.RenderReportAsync(GetType(Telerik.Reporting.Report))
' pass the type of your report here
Dim fileName As String = Convert.ToString(result.DocumentName) & "." & Convert.ToString(result.Extension)
Dim path As String = System.IO.Path.GetTempPath()
Dim filePath As String = System.IO.Path.Combine(path, fileName)
Using fs As New System.IO.FileStream(filePath, System.IO.FileMode.Create)
fs.Write(result.DocumentBytes, 0, result.DocumentBytes.Length)
End Using
Console.WriteLine("Rendering finished on: {0}" & vbLf, Thread.CurrentThread.ManagedThreadId)
' You can return void but that is not recommended
Return String.Format("Successfully rendered! File saved in {0}" & vbLf, filePath)
End Function
Finally, we will invoke this method in a console application and check the results:
class Program
{
// A working example
static void Main(string[] args)
{
// Use your class to render the report in an async manner
var myClass = new MyClass();
Console.WriteLine("Starting rendering...");
var task = myClass.RenderReportAsync();
// While the report is rendering do something else
Count();
Console.WriteLine("Main finished on: {0}", Thread.CurrentThread.ManagedThreadId);
Console.WriteLine("Render Status: {0}\n", task.Result);
Console.ReadLine();
}
static void Count()
{
for (int i = 0; i < 10; i++)
{
Console.WriteLine(i);
}
}
}
Class Program
' A working example
Private Shared Sub Main(args As String())
' Use your class to render the report in an async manner
Dim [myClass] = New [MyClass]()
Console.WriteLine("Starting rendering...")
Dim task = [myClass].RenderReportAsync()
' While the report is rendering do something else
Count()
Console.WriteLine("Main finished on: {0}", Thread.CurrentThread.ManagedThreadId)
Console.WriteLine("Render Status: {0}" & vbLf, task.Result)
Console.ReadLine()
End Sub
Private Shared Sub Count()
For i As Integer = 0 To 9
Console.WriteLine(i)
Next
End Sub
End Class
Additional Resources
Download a sample console application.