The Web Robots FAQ Original of this document is here ˇ http://info.webcrawler.com/mak/projects/robots/faq.html These frequently asked questions about Web robots.
Send suggestions and comments to Martijn Koster.

Table of Contents

  1. About WWW robots
  2. Indexing robots
  3. For Server Administrators
  4. Robots exclusion standard
  5. Availability

About Web Robots


What is a WWW robot?

A robot is a program that automatically traverses the Web's hypertext structure by retrieving a document, and recursively retrieving all documents that are referenced.

Note that "recursive" here doesn't limit the definition to any specific traversal algorithm; even if a robot applies some heuristic to the selection and order of documents to visit and spaces out requests over a long space of time, it is still a robot.

Normal Web browsers are not robots, because the are operated by a human, and don't automatically retrieve referenced documents (other than inline images).

Web robots are sometimes referred to as Web Wanderers, Web Crawlers, or Spiders. These names are a bit misleading as they give the impression the software itself moves between sites like a virus; this not the case, a robot simply visits sites by requesting documents from them.


What is an agent?

The word "agent" is used for lots of meanings in computing these days. Specifically:
Autonomous agents
are programs that do travel between sites, deciding themselves when to move and what to do (e.g. General Magic's Telescript). These can only travel between special servers and are currently not widespread in the Internet.
Intelligent agents
are programs that help users with things, such as choosing a product, or guiding a user through form filling, or even helping users find things. These have generally little to do with networking.
User-agent
is a technical name for programs that perform networking tasks for a user, such as Web User-agents like Netscape Explorer, Email User-agent like Qualcomm Eudora etc.

What is a search engine?

A search engine is a program that searches through some dataset. In the context of the Web, the word "search engine" is most often used for search forms that search through databases of HTML documents gathered by a robot.

What other kinds of robots are there?

Robots can be used for a number of purposes: See the list of active robots to see what robot does what. Don't ask me -- all I know is what's on the list...

So what are Robots, Spiders, Web Crawlers, Worms, Ants

They're all names for the same sort of thing, with slightly different connotations:
Robots
the generic name, see above.
Spiders
same as robots, but sounds cooler in the press.
Worms
same as robots, although technically a worm is a replicating program, unlike a robot.
Web crawlers
same as robots, but note WebCrawler is a specific robot
WebAnts
distributed cooperating robots.

Aren't robots bad for the web?

There are a few reasons people believe robots are bad for the Web: But at the same time the majority of robots are well designed, professionally operated, cause no problems, and provide a valuable service in the absence of widely deployed better solutions.

So no, robots aren't inherently bad, nor inherently brilliant, and need careful attention.


Are there any robot books?

Yes:
Internet Agents: Spiders, Wanderers, Brokers, and Bots by Fah-Chun Cheong.
This books covers Web robots, commerce transaction agents, Mud agents, and a few others. It includes source code for a simple Web robot based on top of libwww-perl4.

Its coverage of HTTP, HTML, and Web libraries is a bit too thin to be a "how to write a web robot" book, but it provides useful background reading and a good overview of the state-of-the-art, especially if you haven't got the time to find all the info yourself on the Web.

Published by New Riders, ISBN 1-56205-463-5.

Bots and Other Internet Beasties by Joseph Williams
I haven't seen this myself, but someone said: The William's book 'Bots and other Internet Beasties' was quit disappointing. It claims to be a 'how to' book on writing robots, but my impression is that it is nothing more than a collection of chapters, written by various people involved in this area and subsequently bound together.

Published by Sam's, ISBN: 1-57521-016-9

Web Client Programming with Perl by Clinton Wong
This O'Reilly book is planned for Fall 1996, check the O'Reilly Web Site for the current status. It promises to be a practical book, but I haven't seen it yet.
A few others can be found on the The Software Agents Mailing List FAQ

Where do I find out more about robots?

There is a Web robots home page on: http://info.webcrawler.com/mak/projects/robots/robots.html

While this is hosted at one of the major robots' site, it is an unbiased and reasoneably comprehensive collection of information which is maintained by Martijn Koster <m.koster@webcrawler.com>.

Of course the latest version of this FAQ is there.

You'll also find details and an archive of the robots mailing list, which is intended for technical discussions about robots.


Indexing robots


How does a robot decide where to visit?

This depends on the robot, each one uses different strategies. In general they start from a historical list of URLs, especially of documents with many links elsewhere, such as server lists, "What's New" pages, and the most popular sites on the Web.

Most indexing services also allow you to submit URLs manually, which will then be queued and visited by the robot.

Sometimes other sources for URLs are used, such as scanners through USENET postings, published mailing list achives etc.

Given those starting points a robot can select URLs to visit and index, and to parse and use as a source for new URLs.

How does an indexing robot decide what to index?

If an indexing robot knows about a document, it may decide to parse it, and insert it into its database. How this is done depends on the robot: Some robots index the HTML Titles, or the first few paragraphs, or parse the entire HTML and index all words, with weightings depending on HTML constructs, etc. Some parse the META tag, or other special hidden tags.

We hope that as the Web evolves more facilities becomes available to efficiently associate meta data such as indexing information with a document. This is being worked on...


How do I register my page with a robot?

You guessed it, it depends on the service :-) Most services have a link to a URL submission form on their search page.

Fortunately you don't have to submit your URL to every service by hand: Submit-it <URL: http://www.submit-it.com/> will do it for you.


For Server Administrators


How do I know if I've been visited by a robot?

You can check your server logs for sites that retrieve many documents, especially in a short time.

If your server supports User-agent logging you can check for retrievals with unusual User-agent heder values.

Finally, if you notice a site repeatedly checking for the file '/robots.txt' chances are that is a robot too.


I've been visited by a robot! Now what?

Well, nothing :-) The whole idea is they are automatic; you don't need to do anything.

If you think you have discovered a new robot (ie one that is not listed on the list of active robots, and it does more than sporadic visits, drop me a line so I can make a note of it for future reference. But please don't tell me about every robot that happens to drop by!


A robot is traversing my whole site too fast!

This is called "rapid-fire", and people usually notice it if they're monitoring or analysing an access log file.

First of all check if it is a problem by checking the load of your server, and monitoring your servers' error log, and concurrent connections if you can. If you have a medium or high performance server, it is quite likely to be able to cope a high load of even several requests per second, especially if the visits are quick.

However you may have problems if you have a low performance site, such as your own desktop PC or Mac you're working on, or you run low performance server software, or if you have many long retrievals (such as CGI scripts or large documents). These problems manifest themselves in refused connections, a high load, performance slowdowns, or in extreme cases a system crash.

If this happens, there are a few things you should do. Most importantly, start logging information: when did you notice, what happened, what do your logs say, what are you doing in response etc; this helps investigating the problem later. Secondly, try and find out where the robot came from, what IP addresses or DNS domains, and see if they are mentioned in the list of active robots. If you can identify a site this way, you can email the person responsible, and ask them what's up. If this doesn't help, try their own site for telephone numbers, or mail postmaster at their domain.

If the robot is not on the list, mail me with all the information you have collected, including actions on your part. If I can't help, at least I can make a note of it for others.


How do I keep a robot off my server?

Read the next section...

Robots exclusion standard


Why do I find entries for /robots.txt in my log files?

They are probably from robots trying to see if you have specified any rules for them using the Standard for Robot Exclusion, see also below.

If you don't care about robots and want to prevent the messages in your error logs, simply create an empty file called robots.txt in the root level of your server.

Don't put any HTML or English language "Who the hell are you?" text in it -- it will probably never get read by anyone :-)


How do I prevent robots scanning my site?

The quick way to prevent robots visiting your site is put these two lines into the /robots.txt file on your server:
User-agent: *
Disallow: /
but its easy to be more selective than that.

Where do I find out how /robots.txt files work?

You can read the whole standard specification but the basic concept is simple: by writing a structured text file you can indicate to robots that certain parts of your server are off-limits to some or all robots. It is best explained with an example:
# /robots.txt file for http://webcrawler.com/
# mail webmaster@webcrawler.com for constructive criticism

User-agent: webcrawler
Disallow:

User-agent: lycra
Disallow: /

User-agent: *
Disallow: /tmp
Disallow: /logs
The first two lines, starting with '#', specify a comment

The first paragraph specifies that the robot called 'webcrawler' has nothing disallowed: it may go anywhere.

The second paragraph indicates that the robot called 'lycra' has all relative URLs starting with '/' disallowed. Because all relative URL's on a server start with '/', this means the entire site is closed off.

The third paragraph indicates that all other robots should not visit URLs starting with /tmp or /log. Note the '*' is a special token; its not a regular expression.

Two common errors:


Will the /robots.txt standard be extended?

Probably... there are some ideas floating around. They haven't made it into a coherent proposal because of time constraints, and because there is little pressure. Mail suggestions to the robots mailing list, and check the robots home page for work in progress.

What if I can't make a /robots.txt file?

Sometimes you cannot make a /robots.txt file, because you don't administer the entire server. All is not lost: there is a new standard for using HTML META tags to keep robots out of your documents.

The basic idea is that if you include a tag like:

<META NAME="ROBOTS" CONTENT="NOINDEX">
in your HTML document, that document won't be indexed.

If you do:

<META NAME="ROBOTS" CONTENT="NOFOLLOW">
the links in that document will not be parsed by the robot.

Availability


Where can I use a robot?

If you mean a search service, check out the various directory pages on the Web, such as Netscape's Exploring the Net or try one of the Meta search services such as MetaSearch

Where can I get a robot?

Well, you can have a look at the list of robots; I'm starting to indicate their public availability slowly.

In the meantime, two indexing robots that you should be able to get hold of are Harvest (free), and Verity's.


Where can I get the source code for a robot?

See above -- some may be willing to give out source code.

Alternatively check out the libwww-perl5 package, that has a simple example.


I'm writing a robot, what do I need to be careful of?

Lots. First read through all the stuff on the robot page then read the proceedings of past WWW Conferences, and the complete HTTP and HTML spec. Yes; it's a lot of work :-)

I've written a robot, how do I list it?

Simply fill in a form you can find on The Web Robots Database and email it to me.
Martijn Koster
Neskol'ko slov o tom, kak rabotayut roboty (spiders) poiskovyh mashin Andrej Alikberov, Centr Informacionnyh Tehnologij

Vvedenie

|ta stat'ya vovse ne yavlyaetsya popytkoj ob®yasnit', kak rabotayut poiskovye mashiny voobshche (eto know-how ih proizvoditelej). Odnako, po moemu mneniyu, ona pomozhet ponyat' kak mozhno upravlyat' povedeniem poiskovyh robotov (wanderers, spiders, robots - programmy, s pomoshch'yu kotoryh ta ili inaya poiskovaya sistema obsharivaet set' i indeksiruet vstrechayushchiesya dokumenty) i kak pravil'no postroit' strukturu servera i soderzhashchihsya na nem dokumentov, chtoby Vash server legko i horosho indeksirovalsya.

Pervoj prichinoj togo, chto ya reshilsya napisat' etu stat'yu, yavilsya sluchaj, kogda ya issledoval fajl logov dostupa k moemu serveru i obnaruzhil tam sleduyushchie dve stroki:

lycosidae.lycos.com - - [01/Mar/1997:21:27:32 -0500] "GET /robots.txt HTTP/1.0" 404 -
lycosidae.lycos.com - - [01/Mar/1997:21:27:39 -0500] "GET / HTTP/1.0" 200 3270

to est' Lycos obratilsya k moemu serveru, na pervyj zapros poluchil, chto fajla /robots.txt net, obnyuhal pervuyu stranicu, i otvalil. Estestvenno, mne eto ne ponravilos', i ya nachal vyyasnyat' chto k chemu.

Okazyvaetsya, vse "umnye" poiskovye mashiny snachala obrashchayutsya k etomu fajlu, kotoryj dolzhen prisutstvovat' na kazhdom servere. |tot fajl opisyvaet prava dostupa dlya poiskovyh robotov, prichem sushchestvuet vozmozhnost' ukazat' dlya razlichnyh robotov raznye prava. Dlya nego sushchestvuet standart pod nazvaniem Standart for Robot Exclusion.

Po mneniyu Luisa Mon'e (Louis Monier, Altavista), tol'ko 5% vseh sajtov v nastoyashchee vremya imeet ne pustye fajly /robots.txt esli voobshche oni (eti fajly) tam sushchestvuyut. |to podtverzhdaetsya informaciej, sobrannoj pri nedavnem issledovanii logov raboty robota Lycos. SHarl' Kollar (Charles P.Kollar, Lycos) pishet, chto tol'ko 6% ot vseh zaprosov na predmet /robots.txt imeyut kod rezul'tata 200. Vot neskol'ko prichin, po kotorym eto proishodit:

Format fajla /robots.txt.

Fajl /robots.txt prednaznachen dlya ukazaniya vsem poiskovym robotam (spiders) indeksirovat' informacionnye servera tak, kak opredeleno v etom fajle, t.e. tol'ko te direktorii i fajly servera, kotorye NE opisany v /robots.txt. |to fajl dolzhen soderzhat' 0 ili bolee zapisej, kotorye svyazany s tem ili inym robotom (chto opredelyaetsya znacheniem polya agent_id), i ukazyvayut dlya kazhdogo robota ili dlya vseh srazu chto imenno im NE NADO indeksirovat'. Tot, kto pishet fajl /robots.txt, dolzhen ukazat' podstroku Product Token polya User-Agent, kotoruyu kazhdyj robot vydaet na HTTP-zapros indeksiruemogo servera. Naprimer, nyneshnij robot Lycos na takoj zapros vydaet v kachestve polya User-Agent:

	Lycos_Spider_(Rex)/1.0 libwww/3.1

Esli robot Lycos ne nashel svoego opisaniya v /robots.txt - on postupaet tak, kak schitaet nuzhnym. Kak tol'ko robot Lycos "uvidel" v fajle /robots.txt opisanie dlya sebya - on postupaet tak, kak emu predpisano.

Pri sozdanii fajla /robots.txt sleduet uchityvat' eshche odin faktor - razmer fajla. Poskol'ku opisyvaetsya kazhdyj fajl, kotoryj ne sleduet indeksirovat', da eshche dlya mnogih tipov robotov otdel'no, pri bol'shom kolichestve ne podlezhashchih indeksirovaniyu fajlov razmer /robots.txt stanovitsya slishkom bol'shim. V etom sluchae sleduet primenyat' odin ili neskol'ko sleduyushchih sposobov sokrashcheniya razmera /robots.txt:

Zapisi (records) fajla /robots.txt

Obshchee opisanie formata zapisi.

[ # comment string NL ]*

User-Agent: [ [ WS ]+ agent_id ]+ [ [ WS ]* # comment string ]? NL

[ # comment string NL ]*

Disallow: [ [ WS ]+ path_root ]* [ [ WS ]* # comment string ]? NL

[

# comment string NL

|

Disallow: [ [ WS ]+ path_root ]* [ [ WS ]* # comment string ]? NL

]*

[ NL ]+

Parametry

Opisanie parametrov, primenyaemyh v zapisyah /robots.txt

[...]+ Kvadratnye skobki so sleduyushchim za nimi znakom + oznachayut, chto v kachestve parametrov dolzhny byt' ukazany odin ili neskol'ko terminov.

Naprimer, posle "User-Agent:" cherez probel mogut byt' ukazany odin ili neskol'ko agent_id.

[...]* Kvadratnye skobki so sleduyushchim za nimi znakom * oznachayut, chto v kachestve parametrov mogut byt' ukazany nol' ili neskol'ko terminov.

Naprimer, Vy mozhete pisat' ili ne pisat' kommentarii.

[...]? Kvadratnye skobki so sleduyushchim za nimi znakom ? oznachayut, chto v kachestve parametrov mogut byt' ukazany nol' ili odin termin.

Naprimer, posle "User-Agent: agent_id" mozhet byt' napisan kommentarij.

..|.. oznachaet ili to, chto do cherty, ili to, chto posle.

WS odin iz simvolov - probel (011) ili tabulyaciya (040)

NL odin iz simvolov - konec stroki (015) , vozvrat karetki (012) ili oba etih simvola (Enter)

User-Agent: klyuchevoe slovo (zaglavnye i propisnye bukvy roli ne igrayut).

Parametrami yavlyayutsya agent_id poiskovyh robotov.

Disallow: klyuchevoe slovo (zaglavnye i propisnye bukvy roli ne igrayut).

Parametrami yavlyayutsya polnye puti k neindeksiruemym fajlam ili direktoriyam

# nachalo stroki kommentariev, comment string - sobstvenno telo kommentariya.

agent_id lyuboe kolichestvo simvolov, ne vklyuchayushchih WS i NL, kotorye opredelyayut agent_id razlichnyh poiskovyh robotov. Znak * opredelyaet vseh robotov srazu.

path_root lyuboe kolichestvo simvolov, ne vklyuchayushchih WS i NL, kotorye opredelyayut fajly i direktorii, ne podlezhashchie indeksirovaniyu.

Rasshirennye kommentarii formata.

Kazhdaya zapis' nachinaetsya so stroki User-Agent, v kotoroj opisyvaetsya kakim ili kakomu poiskovomu robotu eta zapis' prednaznachaetsya. Sleduyushchaya stroka: Disallow. Zdes' opisyvayutsya ne podlezhashchie indeksacii puti i fajly. KAZHDAYA zapis' DOLZHNA imet' kak minimum eti dve stroki (lines). Vse ostal'nye stroki yavlyayutsya opciyami. Zapis' mozhet soderzhat' lyuboe kolichestvo strok kommentariev. Kazhdaya stroka kommentariya dolzhna nachinat'sya s simvola # . Stroki kommentariev mogut byt' pomeshcheny v konec strok User-Agent i Disallow. Simvol # v konce etih strok inogda dobavlyaetsya dlya togo, chtoby ukazat' poiskovomu robotu, chto dlinnaya stroka agent_id ili path_root zakonchena. Esli v stroke User-Agent ukazano neskol'ko agent_id, to uslovie path_root v stroke Disallow budet vypolneno dlya vseh odinakovo. Ogranichenij na dlinu strok User-Agent i Disallow net. Esli poiskovyj robot ne obnaruzhil v fajle /robots.txt svoego agent_id, to on ignoriruet /robots.txt.

Esli ne uchityvat' specifiku raboty kazhdogo poiskovogo robota, mozhno ukazat' isklyucheniya dlya vseh robotov srazu. |to dostigaetsya zadaniem stroki

	User-Agent: *

Esli poiskovyj robot obnaruzhit v fajle /robots.txt neskol'ko zapisej s udovletvoryayushchim ego znacheniem agent_id, to robot volen vybirat' lyubuyu iz nih.

Kazhdyj poiskovyj robot budet opredelyat' absolyutnyj URL dlya chteniya s servera s ispol'zovaniem zapisej /robots.txt. Zaglavnye i strochnye simvoly v path_root IMEYUT znachenie.

Primery.

Primer 1:

User-Agent: *

Disallow: /

User-Agent: Lycos

Disallow: /cgi-bin/ /tmp/

V primere 1 fajl /robots.txt soderzhit dve zapisi. Pervaya otnositsya ko vsem poiskovym robotam i zapreshchaet indeksirovat' vse fajly. Vtoraya otnositsya k poiskovomu robotu Lycos i pri indeksirovanii im servera zapreshchaet direktorii /cgi-bin/ i /tmp/, a ostal'nye - razreshaet. Takim obrazom server budet proindeksirovan tol'ko sistemoj Lycos.

Primer 2:

User-Agent: Copernicus Fred

Disallow:

User-Agent: * Rex

Disallow: /t

V primere 2 fajl /robots.txt soderzhit dve zapisi. Pervaya razreshaet poiskovym robotam Copernicus i Fred indeksirovat' ves' server. Vtoraya - zapreshchaet vsem i osebenno robotu Rex indeksirovat' takie direktorii i fajly, kak /tmp/, /tea-time/, /top-cat.txt, /traverse.this i t.d. |to kak raz sluchaj zadaniya maski dlya direktorij i fajlov.

Primer 3:

# This is for every spider!

User-Agent: *

# stay away from this

Disallow: /spiders/not/here/ #and everything in it

Disallow: # a little nothing

Disallow: #This could be habit forming!

# Don't comments make code much more readable!!!

V primere 3 - odna zapis'. Zdes' vsem robotam zapreshchaetsya indeksirovat' direktoriyu /spiders/not/here/, vklyuchaya takie puti i fajly kak /spiders/not/here/really/, /spiders/not/here/yes/even/me.html. Odnako syuda ne vhodyat /spiders/not/ ili /spiders/not/her (v direktorii '/spiders/not/').

Nekotorye problemy, svyazannye s poiskovymi robotami.

Nezakonchennost' standarta (Standart for Robot Exclusion).

K sozhaleniyu, poskol'ku poiskovye sistemy poyavilis' ne tak davno, standart dlya robotov nahoditsya v stadii razrabotki, dorabotki, nu i t.d. |to oznachaet, chto v budushchem sovsem neobyazatel'no poiskovye mashiny budut im rukovodstvovat'sya.

Uvelichenie trafika.

|ta problema ne slishkom aktual'na dlya rossijskogo sektora Internet, poskol'ku ne tak uzh mnogo v Rossii serverov s takim ser'eznym trafikom, chto poseshchenie ih poiskovym robotom budet meshat' obychnym pol'zovatelyam. Sobstvenno, fajl /robots.txt dlya togo i prednaznachen, chtoby ogranichivat' dejstviya robotov.

Ne vse poiskovye roboty ispol'zuyut /robots.txt.

Na segodnyashnij den' etot fajl obyazatel'no zaprashivaetsya poiskovymi robotami tol'ko takih sistem kak Altavista, Excite, Infoseek, Lycos, OpenText i WebCrawler.

Ispol'zovanie meta-tagov HTML.

Nachal'nyj proekt, kotoryj byl sozdan v rezul'tate soglashenij mezhdu programmistami nekotorogo chisla kommercheskih indeksiruyushchih organizacij (Excite, Infoseek, Lycos, Opentext i WebCrawler) na nedavnem sobranii Distributing Indexing Workshop (W3C) , nizhe.

Na etom sobranii obsuzhdalos' ispol'zovanie meta-tagov HTML dlya upravleniya povedeniem poiskovyh robotov, no okonchatel'nogo soglasheniya dostignuto ne bylo. Byli opredeleny sleduyushchie problemy dlya obsuzhdeniya v budushchem:


ROBOTS meta-tagi

|tot tag prednaznachen dlya pol'zovatelej, kotorye ne mogut kontrolirovat' fajl /robots.txt na svoih veb-sajtah. Tag pozvolyaet zadat' povedenie poiskovogo robota dlya kazhdoj HTML-stranicy, odnako pri etom nel'zya sovsem izbezhat' obrashcheniya robota k nej (kak vozmozhno ukazat' v fajle /robots.txt).

<META NAME="ROBOTS" CONTENT="robot_terms">

robot_terms - eto razdelennyj zapyatymi spisok sleduyushchih klyuchevyh slov (zaglavnye ili strochnye simvoly roli ne igrayut): ALL, NONE, INDEX, NOINDEX, FOLLOW, NOFOLLOW.

NONE - govorit vsem robotam ignorirovat' etu stranicu pri indeksacii (ekvivalentno odnovremennomu ispol'zovaniyu klyuchevyh slov NOINDEX, NOFOLLOW).

ALL - razreshaet indeksirovat' etu stranicu i vse ssylki iz nee (ekvivalentno odnovremennomu ispol'zovaniyu klyuchevyh slov INDEX, FOLLOW).

INDEX - razreshaet indeksirovat' etu stranicu

NOINDEX - nerazreshaet indeksirovat' etu stranicu

FOLLOW - razreshaet indeksirovat' vse ssylki iz etoj stranicy

NOFOLLOW - nerazreshaet indeksirovat' ssylki iz etoj stranicy

Esli etot meta-tag propushchen ili ne ukazany robot_terms, to po umolchaniyu poiskovyj robot postupaet kak esli by byli ukazany robot_terms= INDEX, FOLLOW (t.e. ALL). Esli v CONTENT obnaruzheno klyuchevoe slovo ALL, to robot postupaet sootvetstvenno, ignoriruya vozmozhno ukazannye drugie klyuchevye slova.. Esli v CONTENT imeyutsya protivopolozhnye po smyslu klyuchevye slova, naprimer, FOLLOW, NOFOLLOW, to robot postupaet po svoemu usmotreniyu (v etom sluchae FOLLOW).

Esli robot_terms soderzhit tol'ko NOINDEX, to ssylki s etoj stranicy ne indeksiruyutsya. Esli robot_terms soderzhit tol'ko NOFOLLOW, to stranica indeksiruetsya, a ssylki, sootvetstvenno, ignoriruyutsya.

KEYWORDS meta-tag.

<META NAME="KEYWORDS" CONTENT="phrases">

phrases - razdelennyj zapyatymi spisok slov ili slovosochetanij (zaglavnye i strochnye simvoly roli ne igrayut), kotorye pomogayut indeksirovat' stranicu (t.e. otrazhayut soderzhanie stranicy). Grubo govorya, eto te slova, v otvet na kotorye poiskovaya sistema vydast etot dokument.

DESCRIPTION meta-tag.

<META NAME="DESCRIPTION" CONTENT="text">

text - tot tekst, kotoryj budet vyvodit'sya v summarnom otvete na zapros pol'zovatelya k poiskovoj sisteme. Sej tekst ne dolzhen soderzhat' tagov razmetki i logichnee vsego vpisat' v nego smysl dannogo dokumenta na paru-trojku strok.

Predpolagaemye varianty isklyucheniya povtornyh poseshchenij s pomoshch'yu meta-tagov HTML

Nekotorye kommercheskie poiskovye roboty uzhe ispol'zuyut meta-tagi, pozvolyayushchie osushchestvlyat' "svyaz'" mezhdu robotom i vebmasterom. Altavista ispol'zuet KEYWORDS meta-tag, a Infoseek ispol'zuet KEYWORDS i DESCRIPTION meta-tagi.

Indeksirovat' dokument odin raz ili delat' eto regulyarno?

Vebmaster mozhet "skazat'" poiskovomu robotu ili fajlu bookmark pol'zovatelya, chto soderzhimoe togo ili inogo fajla budet izmenyat'sya. V etom sluchae robot ne budet sohranyat' URL, a brouzer pol'zovatelya vneset ili ne vneset eto fajl v bookmark. Poka eta informaciya opisyvaetsya tol'ko v fajle /robots.txt, pol'zovatel' ne budet znat' o tom, chto eta stranica budet izmenyat'sya.

Meta-tag DOCUMENT-STATE mozhet byt' polezen dlya etogo. Po umolchaniyu, etot meta-tag prinimaetsya s CONTENT=STATIC.

<META NAME="DOCUMENT-STATE" CONTENT="STATIC">

<META NAME="DOCUMENT-STATE" CONTENT="DYNAMIC">

Kak isklyuchit' indeksirovanie generiruemyh stranic ili dublirovanie dokumentov, esli est' zerkala servera?

Generiruemye stranicy - stranicy, porozhdaemye dejstviem CGI-skriptov. Ih navernyaka ne sleduet indeksirovat', poskol'ku esli poprobovat' provalit'sya v nih iz poiskovoj sistemy, budet vydana oshibka. CHto kasaetsya zerkal, to negozhe, kogda vydayutsya dve raznye ssylki na raznye servera, no s odnim i tem zhe soderzhimym. CHtoby etogo izbezhat', sleduet ispol'zovat' meta-tag URL s ukazaniem absolyutnogo URL etogo dokumenta (v sluchae zerkal - na sootvetstvuyushchuyu stranicu glavnogo servera).

<META NAME="URL" CONTENT="absolute_url">

Istochniki

  1. Charles P.Kollar, John R.R. Leavitt, Michael Mauldin, Robot Exclusion Standard Revisited, www.kollar.com/robots.html

  2. Martijn Koster, Standard for robot exclusion, info.webcrawler.com/mak/projects/robots/robots.html
Standart isklyuchenij dlya robotov Standard for robot exclusion

Martijn Koster , perevod A. Alikberova

Status etogo dokumenta

|tot dokument sostavlen 30 iyulya 1994 goda po materialam obsuzhdenij v telekonferencii robots-request@nexor.co.uk (sejchas konferenciya perenesena na WebCrawler. Podrobnosti sm. Robots pages at WebCrawler info.webcrawler.com/mak/projects/robots/) mezhdu bol'shinstvom proizvoditelej poiskovyh robotov i drugimi zainteresovannymi lyud'mi.Takzhe eta tema otkryta dlya obsuzhdeniya v telekonferencii Technical World Wide Web www-talk@info.cern.ch Sej dokument osnovan na predydushchem rabochem proekte pod takim zhe nazvaniem.

|tot dokument ne yavlyaetsya oficial'nym ili ch'im-libo korporativnym standartom, i ne garantiruet togo, chto vse nyneshnie i budushchie poiskovye roboty budut ispol'zovat' ego. V sootvetstvii s nim bol'shinstvo proizvoditelej robotov predlagaet vozmozhnost' zashchitit' Veb-servery ot nezhelatel'nogo poseshcheniya ih poiskovymi robotami.

Poslednyuyu versiyu etogo dokumenta mozhno najti po adresu info.webcrawler.com/mak/projects/robots/robots.html

Vvedenie

Poiskovye roboty (wanderers, spiders) - eto programmy, kotorye indeksiruyut veb-stranicy v seti Internet.

V 1993 i 1994 godah vyyasnilos', chto indeksirovanie robotami serverov poroj proishodit protiv zhelaniya vladel'cev etih serverov. V chastnosti, inogda rabota robotov zatrudnyaet rabotu s serverom obychnyh pol'zovatelej, inogda odni i te zhe fajly indeksiruyutsya neskol'ko raz. V drugih sluchayah roboty indeksiruyut ne to, chto nado, naprimer, ochen' "glubokie" virtual'nye direktorii, vremennuyu informaciyu ili CGI-skripty. |tot standart prizvan reshit' podobnye problemy.

Naznachenie

Dlya togo, chtoby isklyuchit' poseshchenie servera ili ego chastej robotom neobhodimo sozdat' na servere fajl, soderzhashchij informaciyu dlya upravleniya povedeniem poiskovogo robota. |tot fajl dolzhen byt' dostupen po protokolu HTTP po lokal'nomu URL /robots.txt. Soderzhanie etogo fajla sm. nizhe.

Takoe reshenie bylo prinyato dlya togo, chtoby poiskovyj robot mog najti pravila, opisyvayushchie trebuemye ot nego dejstviya, vsego lish' prostym zaprosom odnogo fajla. Krome togo fajl /robots.txt legko sozdat' na lyubom iz sushchestvuyushchih Veb-serverov.

Vybor imenno takogo URL motivirovan neskol'kimi kriteriyami:

Format

Format i semantika fajla /robots.txt sleduyushchie:

Fajl dolzhen soderzhat' odnu ili neskol'ko zapisej (records), razdelennyh odnoj ili neskol'kimi pustymi strokami (okanchivayushchimisya CR, CR/NL ili NL). Kazhdaya zapis' dolzhna soderzhat' stroki (lines) v forme:

"<field>:<optional_space><value><optional_space>".

Pole <field> yavlyaetsya registronezavisimym.

Kommentarii mogut byt' vklyucheny v fajl v obychnoj dlya UNIX forme: simvol # oznachaet nachalo kommentariya, konec stroki - konec kommentariya.

Zapis' dolzhna nachinat'sya s odnoj ili neskol'kih strok User-Agent, sledom dolzhna byt' odna ili neskol'ko strok Disallow, format kotoryh priveden nizhe. Neraspoznannye stroki ignoriruyutsya.

User-Agent