How to make time loop for retrieving web data

Question

I am successfully retrieving the data from webpage by using

Dim webClient As New System.Net.WebClient
Dim result As String = webClient.DownloadString("http://example.org")
MsgBox(result)

However, I need to make it updating, like every 5 minutes it should retrieve the data again. What is the correct approach should be ? Thanks.

using a timer object or control is probably your best solution, just search c# timer and then in the timer_elapsed event you could pull the data. — Kevin, Nov 07 '14 at 20:01
It looks more like a suggestion. Answers should be more detailed. I think thats what he thought, and he is correct. — user198989, Nov 07 '14 at 20:11
If it's going to run for a long time, you may want to think about a Windows service. — Tim, Nov 07 '14 at 20:12
Regarding timers, might wanna check this out : http://stackoverflow.com/questions/1416803/system-timers-timer-vs-system-threading-timer — Victor Zakharov, Nov 07 '14 at 20:14

pedrommuller · Accepted Answer · 2014-11-07T20:58:26.473

1

create a timer set a handler and do the request in every interval

Imports System.Timers
Public Class TimerRequest
    Private Shared aTimer As Timer
    Private Shared o as Object
        Public Shared Sub Main()
             aTimer = New System.Timers.Timer(300000) ' 5 minutes
             AddHandler aTimer.Elapsed, AddressOf OnTimedEvent
             aTimer.Enabled = True
        End Sub  
        Private Shared Sub OnTimedEvent(source As Object, e As ElapsedEventArgs)
            o = CreateObject("InternetExplorer.Application") 
            Dim webClient As New System.Net.WebClient
            Dim result As String = webClient.DownloadString("http://example.org")
            For i As Integer = 0 To 2
                //your loop here
            Next
        End Sub  
 End Class

edited Nov 07 '14 at 20:58

answered Nov 07 '14 at 20:08

pedrommuller

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@user198989: It looks like VB.NET. – Victor Zakharov Nov 07 '14 at 20:13
no, you just need to declare a class, then use the handler – pedrommuller Nov 07 '14 at 20:13
Some of that probably should be a sub routine - maybe a load event? As they cannot be done at class level. – OneFineDay Nov 07 '14 at 20:15
Ahh gotcha http://www.java2s.com/Tutorial/VB/0260__GUI/SetupaneventhandlerfortheTimerElapsedeventcreatesatimerandstartsthetimer.htm – user198989 Nov 07 '14 at 20:20
@user198989 you got it – pedrommuller Nov 07 '14 at 20:21
I'm getting "not declared" when I use the string. How to fix it ? http://i.snag.gy/wAzMf.jpg – user198989 Nov 07 '14 at 20:26
yep results it's out of scope, put your loop into the OnTimeEvent handler – pedrommuller Nov 07 '14 at 20:28
for more info about how closure works read http://blogs.msdn.com/b/vbteam/archive/2007/05/02/closures-in-vb-part-1.aspx – pedrommuller Nov 07 '14 at 20:30
Couldnt do it mate. Could you please help me ? – user198989 Nov 07 '14 at 20:52
Hmm, but there is not hing left in my sub main, should I call this or, how to make this run ? thanks – user198989 Nov 08 '14 at 01:28
you can move eveything yo your main sub – pedrommuller Nov 08 '14 at 01:36
Everything ? I mean.. how can I call this, it should be on sub main right? If I move everything you wrote there to sub main, it doesnt work:( – user198989 Nov 08 '14 at 01:39
post it on a gist I'll take a look tomorrow I'll try to help you – pedrommuller Nov 08 '14 at 01:43
I should call the OnTimedEvent() in main sub correct ? – user198989 Nov 08 '14 at 01:53
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/64538/discussion-between-jack-the-ripper-and-user198989). – pedrommuller Nov 08 '14 at 15:14

How to make time loop for retrieving web data

1 Answers1