sitequery

A reactive framework for asynchronous web crawling.

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A reactive framework for asynchronous web crawling.

sitequery is a reactive webcrawling framework that enables web crawling through server-side execution of jQuery selectors. sitequery uses rx.js to model crawls as async sequence of pages that map to a async sequence of jQuery selected page elements.

sitequery requires a redis installation see: http://redis.io/download

[sudo] npm install sitequery

sitequery has two main abstractions SiteCrawl and SiteQuery which provide the following features:

  • Web crawls can be paramerized to only go n levels deep
  • Configurable crawl timeout
  • Web crawls use a redis store to track visitation and insure a web crawl is cycle-free (no web page is crawled more than once for a given SiteCrawl instance)
  • Any valid jQuery selector can be executed across an entire website (web crawl sequence)
  • Support for the latest jQuery version

(From: /examples/hello-crawl.js)

Allows you to crawl to a depth of n into a website

var SiteCrawl = require('../lib/sitecrawl').SiteCrawl;
 
// create a new SiteCrawl of depth 2 with a delay of 1s between next page and will only run for 10s 
// Note: Webcrawling is delayed and will not be executed 
// until Subscription 
var siteCrawl = new SiteCrawl({url:'http://loku.com',  maxDepth:2, delay:1000, maxCrawlTime:10000});
 
// ask for the observable sequence and subscribe for the CrawlResult(s) 
siteCrawl.toObservable().Subscribe(function(crawlResult) {                 
  console.log(crawlResult.crawlLink.url.href);
},
// on err 
function(exn){
  console.log('Ooo dem Dukes...with exception:' + exn);
},
// on crawl complete 
function(){
  console.log('SiteCrawl complete');
});

(From: /examples/hello-query.js)

Execute jQuery selector to a depth of n on a website

var SiteQuery = require('../lib/sitequery').SiteQuery;
 
// create a new SiteQuery of depth 2 with a delay of 1s between next page crawl 
// selecting for `img` elements on each page 
// Note: Webcrawling is delayed and will not be executed 
// until Subscription 
var siteQuery = new SiteQuery({url:'http://loku.com', maxDepth:2, delay:1000}, 'img');
 
// ask for the observable sequence and subscribe for selected jQuery element(s) 
siteQuery.toObservable().Subscribe(function(result.elem) {
// output the img src                  
  console.log(result.elem.attr('src'));
},
// on err 
function(exn) {
  console.log('Something blowd up with exception:' + exn);
},
// on crawl complete 
function() {
  console.log('SiteQuery complete');
});
  • Make practical - Big performance improvements with version post 0.1.3
  • Obey robots.txt
  • Performance profiling
  • Experiment with jquip
  • Add post-processing backends
  • Graceful errors/degradation for incomplete data/dom for SiteCrawl
  • Handling parse errors more gracefully
  • Simulate auth into the target site when necessary
  • Parallelisation of requests through rx.js ForkJoin
  • Add asynchronous parsing
  • Distribute high-cost computation
  • Make crawl selection plugable
  • Add code to term drain node.js Event queue to insure process termination
Copyright (c) Loku. All rights reserved. The use and
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Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
which can be found in the file epl-v10.html at the root of this
distribution. By using this software in any fashion, you are
agreeing to be bound by the terms of this license. You must
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