Description of URLChecker utility (Michael Drozdov

Description of URLChecker utility

My site contains the rather large list of the links on VFP-sites... and it's rather tiresome occupation from time to time to check: all whether they "alive". I have not found a good utility for this purpose under hands (probably, poorly searched :-) well, ...and I have decided to write myself... Pair of moment predetermining that this utility is written just so, instead of differently:

As there can be any problems during of connection to Web-servers I has decided, that would be not bad to see: as there is a process of verification of the list of links
At me the list of the links are stored in the dbf-file, therefore is necessary to have means export/import of datas from the utility in a format, with which without problems it would be possible to work from VFP. Here I have not invented anything better, than simply text file, the fields in which are divided by symbol TAB
It is necessary to me only to execute monitoring of the existing list of the links, while problems of a storage, editing, watching of a history etc. are carried out means of a database and for the given utility such functionalities are not required
The most part of the links are files of Web-servers, on this I was interested with connection under HTTP-protocol... and only after the utility was written, I have detected, that not bad would be it expand on FTP and NEWS, however my hands have not reached it :-(

Format of text files for export/import:
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It is expected, that the imported text file has the following format:

Unique number	URL-address	Description
Number	String	String

The fields are demarcated by a symbol of horizontal tabulation - '\t' and in an extremity of the right field is marked by new line symbol - '\n'
Attention! The utility is not made any controlling of errors of the indicated format for a text file that your want to import, therefore be are accurate concerning to format of data during to dataorigination, please.

The export of datas is executed in a text file of the following format::

Unique number	URL-address	Description	Result of verification	Status Code
Number	String	String	String	Number

First three columns correspond to the imported file, while last two according to the description of function CHttpFile::QueryInfoStatusCode (...) from MSDN. I shall bring them here, on any case:

Result	Status Code
Success	200-299
Information	300-399
Request error	400-499
Server error	500-599
Undefined	0

The code in the last table line is added by me.

Parameters:
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All parameters has gone in on one tab of the window of properties:

urlchk1.jpg (79411 bytes)

Pic. 1

Auto resize column - on/off mode of selftuning of breadth of two average columns according to modification of a breadth main window.
Auto scroll - on/off mode auto scrolling ensuring visible checking line.
Asynchronous - on/off mode of asynchronous access to external Web-servers.
Time out (sec) - in asynchronous mode a maximum slice of time, on which expiration to terminate attempts of connection to external Web-servers.

Note: Besides an asynchronous mode, I had to allow a possibility synchronous connection, but I very much do not advise to you used it. The problem consists that the small number of Web-servers breaks off asynchronous connection before I manage to receive from them an information (from all two hundred sites such there were only some pieces at me :-)... Certainly, very much even can be, that I did not manage simply on all 100% correctly to write a code of processing asynchronous connection :-( On synchronous mode of connection indicated breaks off connections does not happen, however in this case there is no possibility to break off process of communication with the Web-server, except to finish process from System Task Manager :-( while in an asynchronous mode, such connections interrupt by error without any of an exit code (Undefined) or on the expiration of Time out. Apparently, it is necessary in addition to check up such sites from IE. ... And it will not be a primary amount sites, not so whether :-)

Execute verification:
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All is very simple. Only choice menu item Options/Start ... and you can observe process of checking of the links. Well, if you will interrupt process (by menu item Options/Stop), there will be a condition, similar shown on following picture:

urlchk2.jpg (31615 bytes)

Pic. 2

Pay attention, that the link, on which the process of monitoring was interrupted, is in a condition Aborted (third line on picture 2). After that, you can continue monitoring since the interrupted link - Options/Continue, ... well, or all at first...

Current condition of datas you can save/read on disk files with the .uck extension

Final notes:
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This utility I have written for myself and has exhibited it extremely only in hope, that it still will help to somebody... Nevertheless has a place an annoying problem explained in note :-(
In that kind "as is", it perhaps allows only to detect the list of the links, which have those or other problems, for clearing up: which additional analysis is required.
I used MS VC++ 6.0 and Controls from delivery SP4 for VS 6.0, if it at you is not present, see Visual Studio® 6.0 Service Pack 4 (SP4) on http://msdn.microsoft.com/vstudio/sp/vs6sp4/default.asp - SP4 includes of all previous service packages (SP3, SP2 and SP1) and it is recommended for all tools which are included in Visual Studio 6.0...

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