Check if a webpage is online using VB in asp.net

Question

I have been toying with getting this working for a while now to no avail.

I want to check if a website is available and display its status in a label. I have no code to share as I haven't got this anywhere close. I am using VS 2013 building a asp.net website using VB.

I thought I could just ping the website but after multiple test using command.exe the website doesn't respond to pings even when up.

I know the page will be taken offline periodically for updates as this happened last week and when it is you get page cannot be displayed. I need to test if the page is online and return true if it is and false if not.

Is it your website or a 3rd party's? If you have control over the site you could dump a small text file in the root with the status, means if it's down for maintenance etc. you could update this and read it from your app. — James, Nov 01 '13 at 13:43
ping is an ICMP tool that *might* have told you if the server was switched on but would have given you no information about what services (except Ping) were running. Is it enough to check that a page is returned when trying to access the website? What if that page just contains the text "this service is not available"? — Damien_The_Unbeliever, Nov 01 '13 at 13:44
A lot of websites won't respond to ping so that's definitely not a reliable method. — nycdan, Nov 01 '13 at 13:52

score 2 · Accepted Answer · edited May 23 '17 at 11:44

2

The simple way is to do an httpWebRequest and examine the result. If the page doesn't exist, you will get an error that indicates that. I'm not as familiar with .webClient but that apparently works as well.

This past question gives you examples of both.

edited May 23 '17 at 11:44

Community

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answered Nov 01 '13 at 13:45

nycdan

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score 1 · Answer 2 · answered Nov 01 '13 at 13:45

1

You can easily do this using HttpWebRequest.

try {
    HttpWebRequest myHttpWebRequest = (HttpWebRequest) WebRequest.Create("siteAddress");
    HttpWebResponse myHttpWebResponse = (HttpWebResponse) myHttpWebRequest.GetResponse();
    myHttpWebResponse.Close();
}
catch(WebException e) {
    //There is a problem accessing the site
}

answered Nov 01 '13 at 13:45

Tim Ebenezer

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Will a 404 return an error? I don't believe so in which case this catch won't help. You'll have to parse what the server returns. Not hard to do though. – nycdan Nov 01 '13 at 13:49
@nycdan, 404, would be an exception, caught in `WebException` – Habib Nov 01 '13 at 13:58
Thanks. I missed that. – nycdan Nov 01 '13 at 13:59

Check if a webpage is online using VB in asp.net

2 Answers2