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For 2023 (and 2024 ...) - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))
Mirroring a dynamic site

We're delighted to welcome crawlers such as Yahoo, Inktomi, Google and MSN spiders through our web site to index content - it's in our mutual interest. Those crawlers are all well written to analyse the pages that they collect, note patterns, and tailor their activities to make the best use of a dynamic site with 16 alternative versions (4 x font sets, 4 x colour sets) of displaying each page.

Robots which simply collect the whole of a web site for local offline browsing, such as HTTrack and (in some guises) Wget can be more problematic; they're simply not well formed to mirror dynamic sites and will try to gather every possible page, skewing web statistics and in bad cases leading to restriction of our resources for others. And it's doubtful whether any realistic use will be made of the data gathered.

I was watching HTTrack struggling to copy our dynamic website to a static mirror yesterday morning - every 4 seconds, another hit; it took 5 minutes just to get the help pages for the adhoc query demo by the time it had them in green on black in a tiny font, blue on yellow in a huge font, and all the intermediate settings. It's a waste of our resources and, frankly, I doubt whether the person making the mirror will find it of any use.

So as a web site owner, should I discourage such mirroring, and if so, how?

My first thought is to modify my robots.txt file to disallow all downloads by wget and httrack - except that I would need to check that they actually respect the standard before I go to the trouble, and that in any case we WELCOME user who sensibly use the utilities to download a few pages for offline viewing.

A second thought is to use my denial of service mechanism to trigger a delay where file access from a single remote host get delayed once they reach a certain threshold in a certain time - except that this would be just as likely to trap the legitimate / welcomed "bots" unless I put in some user agent specific logic that would need to be high maintenance - updated as new agents come along. And I certainly don't want to go down the "ban xxx IP address" road either.

A look at the HTTrack FAQ rather confirms my worries that neither of the above solutions is ideal; although it respects robots.txt, that can be turned off. Advise to users suggests that they use time limits and for large mirrors, ask the webmaster first and try not to download during working hours and do not download too large websites - use filters and I see all four of these pieces of advise NOT followed ... it also advises Are the pages copyrighted and, yes, they are.

But, in reality, it's no great issue to us if one or two users pull huge amounts of files they'll never use off our system.
(written 2006-04-12, updated 2006-06-05)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
G902 - Well House Consultants - Web site techniques, utility and visibility
  [23] Skills and responsibilities - (2004-08-22)
  [32] Web design platoon - (2004-08-29)
  [98] No more 'Error 404' pages. Something better. - (2004-10-24)
  [109] URLs - a service and not a hurdle - (2004-11-04)
  [117] A case of case - (2004-11-14)
  [142] Colour for access - (2004-12-06)
  [165] Implementing an effective site search engine - (2005-01-01)
  [173] Data Mining - (2005-01-09)
  [179] The hunt for unique words - (2005-01-16)
  [182] Your personal Google ranking - (2005-01-19)
  [197] Allow for peak traffic on your web site - (2005-02-01)
  [202] Searching for numbers - (2005-02-04)
  [222] Who are all these visitors? - (2005-02-20)
  [259] Responding to spam - (2005-03-27)
  [261] Putting a form online - (2005-03-29)
  [268] Information request forms, cleaning up spam - (2005-04-05)
  [274] Our most popular resources - (2005-04-10)
  [276] An apology to Mr Boneparte - (2005-04-11)
  [278] Cover all the options - (2005-04-13)
  [284] The Iconish language - (2005-04-19)
  [288] Colour blindness for web developers - (2005-04-22)
  [311] Growth pains - (2005-05-14)
  [314] What language is this written in? - (2005-05-17)
  [320] Ordnance Survey - using a 'Get a map' - (2005-05-22)
  [322] More maps - (2005-05-23)
  [347] Frightening and from-friend viruses and spams - (2005-06-14)
  [348] Graveyard pages - (2005-06-15)
  [369] CMS - the minefield of Choices - (2005-07-05)
  [376] What brings people to my web site? - (2005-07-13)
  [414] Form Madness - (2005-08-14)
  [492] New Navigation Aid - Launch of My Wellho - (2005-11-11)
  [510] Dynamic Web presence - next generation web site - (2005-11-29)
  [528] Getting favicon to work - avoiding common pitfalls - (2005-12-14)
  [533] Bigger Box Campaign - (2005-12-18)
  [649] Denial of Service ''attack'' - (2006-03-17)
  [658] Keeping the visitors happy and browsing - (2006-03-26)
  [718] Protecting images from theft - (2006-05-12)
  [732] Where is a web site visitor browsing from - (2006-05-24)
  [757] Horse and Python training - (2006-06-12)
  [767] Finding the language preference of a web site visitor - (2006-06-18)
  [800] Effective web campaign? - (2006-07-12)
  [893] Visibility - (2006-10-14)
  [916] Driving customers away - (2006-11-07)
  [976] Santa at the station - (2006-12-09)
  [994] Training on Cascading Style Sheets - (2006-12-17)
  [1015] Search engine placement - long term strategy and success - (2006-12-30)
  [1029] Our search engine placement is dropping. - (2007-01-11)
  [1055] Above the fold - (2007-01-28)
  [1104] Drawing dynamic graphs in PHP - (2007-03-09)
  [1177] Sorting out for a site map - (2007-05-05)
  [1184] Finding resources - some pointers - (2007-05-13)
  [1186] Two new pages / sites - (2007-05-14)
  [1198] From Web to Web 2 - (2007-05-21)
  [1207] Simple but effective use of mod_rewrite (Apache httpd) - (2007-05-27)
  [1212] What brought YOU to our web site? - (2007-06-01)
  [1237] What proportion of our web traffic is robots? - (2007-06-19)
  [1297] Stuffing content into a web page - easy maintainance - (2007-08-09)
  [1437] Above the fold with First Great Western - (2007-11-19)
  [1494] A time to update pictures - (2008-01-03)
  [1505] Script to present commonly used images - PHP - (2008-01-13)
  [1506] Ongoing Image Copyright Issues, PHP and MySQL solutions - (2008-01-14)
  [1513] Perl, PHP or Python? No - Perl AND PHP AND Python! - (2008-01-20)
  [1534] Where in the world / country is my visitor from? - (2008-02-07)
  [1541] Colour, Composition or Content - (2008-02-16)
  [1554] Online hotel reservations - Melksham, Wiltshire (near Bath) - (2008-02-24)
  [1610] PHP course dot co, dot uk - (2008-04-13)
  [1630] To provide external links, or not? - (2008-05-04)
  [1634] Kiss and Book - (2008-05-07)
  [1653] How do Google Ads work? - (2008-05-25)
  [1711] Rapid growth leads to server move - (2008-07-17)
  [1747] Who is watching you? - (2008-08-10)
  [1756] Ever had One of THOSE mornings? - (2008-08-16)
  [1793] Which country does a search engine think you are located in? - (2008-09-11)
  [1797] I have been working hard but I do not expect you noticed - (2008-09-14)
  [1833] Web Bloopers - good form design - avoiding pitfalls - (2008-10-11)
  [1856] A few of my favourite things - (2008-10-26)
  [1888] Find the link - (2008-11-16)
  [1955] How to avoid duplicating web page maintainance - (2008-12-20)
  [1961] Making our things easier to find - (2008-12-26)
  [1970] Plagarism - who is copying my pages? - (2009-01-02)
  [1982] Cooking bodies and URLs - (2009-01-08)
  [2056] Web Site Loading - experiences and some solutions shared - (2009-02-26)
  [2065] Static mirroring through HTTrack, wget and others - (2009-03-03)
  [2225] How important is a front page ranking on a search engine? - (2009-06-09)
  [2332] Formation, des langages Open Source - (2009-08-09)
  [2333] Formaci[83][c2]ón, de los lenguajes de c[83][c2]ódigo abierto - (2009-08-09)
  [2334] Formazione, Open Source computer lingue - (2009-08-09)
  [2335] Ausbildung, die Open-Source-Sprachen - (2009-08-09)
  [2336] Forma[83][c2]ç[83][c2]ão, Open Source computador l[83][c2]ínguas - (2009-08-09)
  [2337] Opleiding, Open Source computertalen - (2009-08-09)
  [2338] Uddannelse, Open Source computer sprog - (2009-08-09)
  [2339] Oppl[83][c2]æring, Open Source datamaskinen spr[83][c2]åk - (2009-08-09)
  [2340] ldning, Open Source dator spr[83][c2]åk - (2009-08-09)
  [2341] Koulutus, Open Source tietokone kielill[83][c2]ä - (2009-08-09)
  [2389] Writing with our customers words - (2009-09-01)
  [2410] Removal of technical resources from this site - (2009-09-19)
  [2519] Status Page / breaks of service in early December - (2009-11-30)
  [2532] Analysing Google arrivals by country of origin - (2009-12-10)
  [2552] Web site traffic - real users, or just noise? - (2009-12-26)
  [2569] How to run a successful online poll / petition / survey / consultation - (2010-01-10)
  [2668] Is it worth it? - (2010-03-09)
  [2981] How to set up short and meaningfull alternative URLs - (2010-10-02)
  [3022] Retaining web site visitors - reducing the one page wonders - (2010-10-31)
  [3087] Making the most of critical emails - reading behind the scene - (2010-12-16)
  [3149] Looking back at www.wellho.net - (2011-01-28)
  [3197] Finding and diverting image requests from rogue domains - (2011-03-08)
  [3367] Google +1 - what is it? - (2011-07-22)
  [3426] Automed web site testing scripted in Ruby using watir-webdriver - (2011-09-09)
  [3491] Who is knocking at your web site door? Are you well set up to deal with allcomers? - (2011-10-21)
  [3532] Sharing the user experience - designing a form with the customer in mind - (2011-11-29)
  [3554] Learning more about our web site - and learning how to learn about yours - (2011-12-17)
  [3563] How big is a web page these days? Does the size of your pages matter? - (2011-12-26)
  [3589] Promoting a single one of your domains on the search engines - (2012-01-22)
  [3623] Some TestWise examples - helping use Ruby code to check your web site operation - (2012-02-24)
  [3734] QR codes with marketing logos embedded - (2012-05-16)
  [3744] Short Web Addresses for Melksham - (2012-05-30)
  [3745] Legal change - You need to obtain user consent if you use cookies on your website - (2012-06-01)
  [3776] Some traps it's so easy to fall into in designing your web site - (2012-06-23)
  [3896] An email marathon - (2012-10-15)
  [3974] TV show appearance - how does it effect your web site? - (2013-01-13)
  [4001] Helping search engines with appropriate 400 error codes - (2013-02-11)
  [4076] Web site - fully back! - (2013-04-29)
  [4115] More or less back - what happened to our server the other day - (2013-06-14)
  [4136] How do I post automatically from a PHP script to my Twitter account? - (2013-07-10)
  [4239] Facebook marketing - early experiences - (2014-01-19)
  [4376] Well House Consultants, Well House Manor, First Great Western Coffee shop, TransWilts / 2014 web site reports - (2015-01-01)
  [4401] Selecting RECENT and POPULAR news and trends for your web site users - (2015-01-19)
  [4474] Effect on external factors on traffic to our web sites - an update - (2015-04-26)
  [4492] Almost so wrong, but perhaps it's right for some? - (2015-05-11)


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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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