Technology is all about reducing your labour work, reducing the efforts for performing a task and increasing the productivity by providing advanced means. As we all are aware about the mobile world hitting to the top of world these days. The smart phones are gathering up such amazing applications which are able to perform every critical task easily. Among the services provided by technology, Crawling and Scraping is one of the essential part of internet services these days.
Now-a-days, Content is a king of internet ,insight of intelligent people. So, every second rushes to the search engine in order to complete a query or to raise a request or even to lodge a complaint. If you want to extract information or want to collect any statistics, Crawler Development is a big relief. Read more about them.
Before going towards the comparison, let us figure out the basis of scraping and crawling. In actual, what these terms depict.
- Can be referred as retrieving information
- Can be called as web harvesting or data extraction
- Processing of web document
- Acts as extracter
- Focussed and intentional way of working
- Programmatic analysis of web page to collect information
- Coded differently which is generally targeted at certain websites
- Often used for illegal access
- process of extracting information from local host, database or even from the links provided, also come under data scraping
- This not necessarily includes deduplication
- Web scraping is used for contact scraping
- As a component of apps which are used for data mining and indexing of web
- Also called as an automatic indexer
- Deals with large sets of data
- Viewing a page as a whole and indexing it
- Deduplication is the integral part of crawling which is usually done to save the memory of the server
- Usually called as a spider
- Acts as an internet bot which browses world wide web systematically
Strategies followed by a Crawler
- Selection – which pages to download
- Revisit – when to check for modifications in the page
- Politeness – avoid overloading pages
- Parallelization – how to coordinate distributed web crawlers
More about Scraping :
- Scraping of data includes a simple program which fetches source HTML of web pages to process it
- Easiest way of scraping includes using expressions string matching facilities of the scripting languages used by it
- Well known scripting languages such as, PHP/Python/Perl include built in primitives and libraries for obtaining HTML in a single LOC (line of codes) .
Tools Used for scraping can be shown as :
- HTML parser – such as neko html, mozilla parser
- Query languages – like xpath, regxp,GATE, Tregexp
Techniques adapted by Web Scraping can be summarised as :
- Human copy & paste
- Text pattern matching
- Parsing which can be further divided as : HTML & DOM
- Aggregation (vertical)
Now let us have a look over the difference between both, though both are closely related to each other.
|Dedup is merely an add on||Dedup is integral|
|Has website to scrap||Deals with large data sets|
|Scraping means searching||Crawling refers to indexing|
|Often used for illegal access||Always done for legal and good works|
|Programmatic collection of visual data from a source||Stands for extracting contents without watching the results|
|Is considered as an adhoc, illegal technique||Directive like “disallow” goes for robot.txt|
|Ia extracting data from human read output source||Obtains url’s from crawling engines feed from different sources|
Web scraping and web crawling are closely related to each other. But at some aspects the similarity between them gets elongated on basis of their strategies followed. But both of the techniques are ruling the internet these days as they are providing very less labor to everyone.
Keep reading for more informative blogs.