[Lazarus] Detecting if a remote web server is running
Hi All, What's the most reliable way of detecting whether a remote website is responding? Thanks Richard -- ___ Lazarus mailing list Lazarus@lists.lazarus.freepascal.org http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus
Re: [Lazarus] Detecting if a remote web server is running
maybe ping? On Thu, Oct 30, 2014 at 10:44 AM, Richard Mace richard.m...@gmail.com wrote: Hi All, What's the most reliable way of detecting whether a remote website is responding? Thanks Richard -- ___ Lazarus mailing list Lazarus@lists.lazarus.freepascal.org http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus -- Felipe Monteiro de Carvalho -- ___ Lazarus mailing list Lazarus@lists.lazarus.freepascal.org http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus
Re: [Lazarus] Detecting if a remote web server is running
On Thu, Oct 30, 2014 at 6:44 AM, Richard Mace richard.m...@gmail.com
wrote:
Hi All,
What's the most reliable way of detecting whether a remote website is
responding?
Get the HTTP headers:
uses
fphttpclient;
procedure TForm1.Button1Click(Sender: TObject);
var
VHttp: TFPHTTPClient;
VHeaders: TStrings;
begin
VHttp := TFPHTTPClient.Create(nil);
VHeaders := TStringList.Create;
try
VHttp.RequestHeaders.Add('Connection: Close');
VHttp.Head('http://lazarus.freepascal.org', VHeaders);
if VHeaders.Count 0 then
ShowMessage('OK')
else
ShowMessage('Fail');
finally
VHeaders.Free;
VHttp.Free;
end;
end;
--
Silvio Clécio
My public projects - github.com/silvioprog
--
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Re: [Lazarus] Detecting if a remote web server is running
Richard, There is no substitute for suck it and see. I have a web server that I need to ensure keeps running. I monitor it from another system that runs a CRON job every five minutes that uses wget to download the home page. If this fails it EMails me. As you are putting this on the lazarus list. I assume that you want to do something similar from an interactive Pascal program. Here there is no substitute for good error handling. My experience is with the indy components and these will raise an exception if they can't download a given webpage (timeout). You can catch this and give the user an appropriate error message when they try to access a non-responding server. You could even have a background thread to keep doing this, if it is really important to tell the user as soon as possible. Tony Whyman MWA On 30/10/14 09:44, Richard Mace wrote: Hi All, What's the most reliable way of detecting whether a remote website is responding? Thanks Richard -- ___ Lazarus mailing list Lazarus@lists.lazarus.freepascal.org http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus -- ___ Lazarus mailing list Lazarus@lists.lazarus.freepascal.org http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus
Re: [Lazarus] Detecting if a remote web server is running
On Thu, 30 Oct 2014 12:29:00 +0100 Felipe Monteiro de Carvalho felipemonteiro.carva...@gmail.com wrote: maybe ping? Many servers do not respond to ping. So not reliable. Mattias -- ___ Lazarus mailing list Lazarus@lists.lazarus.freepascal.org http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus
Re: [Lazarus] Detecting if a remote web server is running
On 10/30/2014 7:29 AM, Felipe Monteiro de Carvalho wrote: On Thu, Oct 30, 2014 at 10:44 AM, Richard Mace richard.m...@gmail.com wrote: Hi All, What's the most reliable way of detecting whether a remote website is responding? maybe ping? ping might tell you if the IP address is active but that's all... it won't tell you if the server is running or servicing requests... you have to request something from the server to see if it is servicing requests... the easiest and smallest would be to request the headers (only) from the root... -- NOTE: No off-list assistance is given without prior approval. Please *keep mailing list traffic on the list* unless private contact is specifically requested and granted. -- ___ Lazarus mailing list Lazarus@lists.lazarus.freepascal.org http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus
Re: [Lazarus] Detecting if a remote web server is running
On Thu, Oct 30, 2014 at 11:39 AM, waldo kitty wkitt...@windstream.net wrote: On 10/30/2014 7:29 AM, Felipe Monteiro de Carvalho wrote: On Thu, Oct 30, 2014 at 10:44 AM, Richard Mace richard.m...@gmail.com wrote: Hi All, What's the most reliable way of detecting whether a remote website is responding? maybe ping? ping might tell you if the IP address is active but that's all... it won't tell you if the server is running or servicing requests... you have to request something from the server to see if it is servicing requests... the easiest and smallest would be to request the headers (only) from the root... +1 Like this: http://lists.lazarus.freepascal.org/pipermail/lazarus/2014-October/089112.html -- Silvio Clécio My public projects - github.com/silvioprog -- ___ Lazarus mailing list Lazarus@lists.lazarus.freepascal.org http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus
Re: [Lazarus] Detecting if a remote web server is running
Thanks for everyone's replies, very helpful. Richard On 30 October 2014 14:42, silvioprog silviop...@gmail.com wrote: On Thu, Oct 30, 2014 at 11:39 AM, waldo kitty wkitt...@windstream.net wrote: On 10/30/2014 7:29 AM, Felipe Monteiro de Carvalho wrote: On Thu, Oct 30, 2014 at 10:44 AM, Richard Mace richard.m...@gmail.com wrote: Hi All, What's the most reliable way of detecting whether a remote website is responding? maybe ping? ping might tell you if the IP address is active but that's all... it won't tell you if the server is running or servicing requests... you have to request something from the server to see if it is servicing requests... the easiest and smallest would be to request the headers (only) from the root... +1 Like this: http://lists.lazarus.freepascal.org/pipermail/lazarus/2014-October/089112.html -- Silvio Clécio My public projects - github.com/silvioprog -- ___ Lazarus mailing list Lazarus@lists.lazarus.freepascal.org http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus -- ___ Lazarus mailing list Lazarus@lists.lazarus.freepascal.org http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus
