The infoboxes, which is what this guy is scraping, are much easier to scrape from the HTML than from the XML dumps.
The reason is that the dumps just have pointers to templates, and you need to understand quite a bit about Wikipedia's bespoke rendering system to know how to fully realize them (or use a constantly-evolving library like wtf_wikipedia [1] to parse them).
The rendered HTML, on the other hand, is designed for humans, and so what you see is what you get.
You could, and if he was doing this on the entire corpus that'd be the responsible thing to do.
But, his project really was very reasonable:
- it fetched ~2,400 pages
- he cached them after first fetch
- Wikipedia aggressively caches anonymous page views (eg the Queen Elizabeth page has a cache age of 82,000 seconds)
English Wikipedia does about 250,000,000 pageviews/day. This guy's use was 0.001% of traffic on that day.
I get the slippery slope arguments, but to me, it just doesn't apply. As someone who has donated $1,000 to Wikipedia in the past, I'm totally happy to have those funds spent supporting use cases like this, rather than demanding that people who want to benefit from Wikipedia be able to set up a MySQL server, spend hours doing the import, install and configure a PHP server, etc, etc.
He was probably one of the biggest users that day, so that makes sense.
The 2,400 pages, assuming a 50 KB average gzipped size, equate to 120 MB of transfer. I'm assuming CPU usage is negligible due to CDN caching, and so bandwidth is the main cost. 120 MB is orders of magnitude less transfer than the 18.5 GB dump.
Instead of the dumps, he could have used the API -- but would that have significantly changed the costs to the Wikimedia foundation? I think probably not. In my experience, the happy path (serving anonymous HTML) is going to be aggressively optimized for costs, eg caching, CDNs, negotiated bandwidth discounts.
If we accept that these kinds of projects are permissible (which no one seems to be debating, just the manner in which he did the project!), I think the way this guy went about doing it was not actually as bad as people are making it out to be.
That's true. On the other hand, pages with infoboxes are likely well-linked and will end up in the cache either due to legitimate popularity or due to crawler visits.
Checking a random sample of 50 pages from this guy's dataset, 70% of them were cached.
Note - there's several levels of caching at wikipedia. Even if those pages aren't in cdn (varnish) cache, they may be in parser cache (an application level cache of most of the page).
This amount of activity really isn't something to worry about, especially when taking the fast path of logged out user viewing a likely to be cached page.
En wikipedia has some standards. Generally though they are user-created tables and its up to the users to make them consistent (if they so desire). En Wikipedia generally does, but its not exactly a hard garuntee.
If you want machine readable use wikidata (if you hate rdf you can still scrape the html preview of the data)
Even just being able to download a tarball of the HTML of the infoboxes would be really powerful, setting aside the difficulty of, say, translating them into a consistent JSON format.
That plus a few other key things (categories, opening paragraph, redirects, pageview data) enable a lot of powerful analysis.
That actually might be kind of a neat thing to publish. Hmmmm.
Better yet-- what is the set of wikipedia articles which have an info box that cannot be sensibly interpreted as key/value pairs where the key is a simple string?
Hehe-- I am going to rankly speculate nearly all of them follow an obvious standard of key/value pairs where the key is a string. And then there are like two or three subcultures on Wikipedia that put rando stuff in there and would troll to the death before being forced to change the their infobox class to "rando_box" or whatever negligible effort it would take them if a standard were to be enforced.
That's the great thing about HtmlAgilityPack, extracting data from HTML is really easy. I might even say even easier than if I had the page in some table-based data system.
Unlike APIs, html class/tag names or whatever provide no stability guarantees. The site owner can break your parser whenever they want for any reason. They can do that with an API, but usually won't since some guarantee of stability is the point of an API.
True, but the analysis was done on files downloaded over the span of two or three days. If someone had decided to change the CSS class of an infobox during that time, I'd have noticed, investigated and adjusted my code appropriately.
Scrapping, especially on a large scale, can put a noticeable strain on servers.
Bulk downloads (database dumps) are much cheaper to serve for someone crawling millions of pages.
It gets even more significant if generation of reply is resource intensive (not sure is Wikipedia qualifying for that but complex templates may cause this).
IANAL but since the pages are published under Creative Commons Attribution-ShareAlike, if someone wishes to collect the text on the basis of the HTML version then there's not much you can do about it.
Wikimedia no doubt have caching, CDNs and all that jazz in place so the likely impact on infrastructure is probably de-minimis in the grand scheme of things (the thousands or millions of humans who visit the site every second).
>IANAL but since the pages are published under Creative Commons Attribution-ShareAlike, if someone wishes to collect the text on the basis of the HTML version then there's not much you can do about it.
They said please don't, not don't do it or they'll sue you.
But content license and site terms of use are different things.
From their terms of use you aren’t allowed to
> [Disrupt] the services by placing an undue burden on a Project website or the networks or servers connected with a Project website;
Wikipedia is also well within their rights to implement scraping countermeasures.
Yes, but they aren't going to care for just 2400 pages.
As a general rule, make your scraper non-paralell, and put a user-agent that has contact details in the event of an issue, and you're probably all good.
After all wikipedia is meant to be used. Don't be unduly disruptive, don't scrape 20 million pages, but scraping a couple thousand is totally acceptable.
Source: used to work for wikimedia, albeit not in the sre dept. My opinions are of course totally my own.
Honestly i'd rather people err on the side of scrapping wikipedia too much than live in fear of being disruptive and not do cool things as a result. Wikipedia is meant to be used to spread knowledge. That includes data mining projects such as the one in this blog.
(Before anyone takes this out of context - no im not saying its ok to be intentionally disruptive, or do things without exercising any care at all. Also always set a unique descriptive user-agent with an email address if you're doing anything automated on wikipedia).
Having been on the other side of this, I’d rather we encourage people to make use of formats/interfaces designed for machines and use the right tool for the job instead of scraping everything.
It’s incredibly easy for careless scrapers to disrupt a site and cost real money without having a clue what they’re doing.
I want people to think twice and consider what they are doing before they scrape a site.
> [Disrupt] the services by placing an undue burden on a Project website or the networks or servers connected with a Project website;
Two things:
1) The English wikipedia *alone* gets 250 million page views per day ! So you would have to be doing an awful lot to cause "undue burden".
2) The Wikipedia robots.txt page openly implies that crawling (and therefore scraping) is acceptable *as long as* you do it in a rate-limited fashion, e.g.:
>Friendly, low-speed bots are welcome viewing article pages, but not dynamically-generated pages please.
> There are a lot of pages on this site, and there are some misbehaved spiders out there that go _way_ too fast.
>Sorry, wget in its recursive mode is a frequent problem. Please read the man page and use it properly; there is a --wait option you can use to set the delay between hits, for instance.
1. You'd be surprised what kind of traffic scrapers can generate. I've seen scraping companies employing botnets to get around rate limiting that could easily cost enough in extra server fees to cause an "undue burden".
At a previous company we had the exact problem that we published all of our content as machine readable xml, but we had scrapers costing us money by insisting on using our search interface to access our content.
2. No one is going to jail for scraping a few thousand or even a few million pages, but just because low speed web crawlers are allowed to index the site, doesn't mean scraping for every possible use is permitted.
"Who's gonna stop me" is kind of a crappy attitude to take with a cooperative project like Wikipedia.
I mean, sure, you can do a lot of things you shouldn't with freely available services. There's even an economics term that describes this: the Tragedy of the Commons.
Individual fish poachers' hauls are also, individually, de-minimis.
