Receiving big volumes of data from websites for its following analysis plays a key role for plenty of projects. Target resource structure analysis and scraping of the relevant information are often connected to blocks or access restriction issues from website administration.
To make data collection faster and easier, we recommend you to follow a number of guidelines based on websites work features. In this article we’ve put together several recommendations to ease up your work with parsers and search engines.
Robot exclusion standard
Major web-resources open access to robots.txt file for all the visitors. The file contains access restrictions settings to the whole website or to some of its particular pages. This methodology is set by the robot exclusion standard.This way owners of web-resources are able to regulate access of search engines crawlers to some sections of their website.
Before starting collecting data from the web-page, you might find it useful to familiarize yourself with existing exceptions. If the resource you need allows using crawlers, you should use it carefully without breaking the request limit and collecting data in the low server’s load period.
However, it doesn’t grant complete absence of restrictions on crawling and parsing of data. That’s why it’s also recommended to use other guidelines.
Connecting through proxy server
Using proxy is one of the most important nuances in any project connected to parsing or crawling of web-services. The efficiency of data collection largely depends on the correct choice of package
Depending on the specifics of your tasks, server-based, mobile or residential proxies might fit you differently. If the required traffic volume is small, the best solution would be to use Exclusive packages.
Working through proxies located in different locations will allow you to bypass blockages associated with regional restrictions, allow you to significantly expand the limit on the number and intensity of requests, and increase your anonymity on the Web.
In tasks requiring a large number of connections to a target resource, you may encounter blocking by IP address even when using proxy servers. Most often this happens if a proxy itself has a static IP.
The solution is to use a proxy with IP rotation. On RSocks you can find packages in which proxies are updated every 3 hours, an hour, and even every 5 minutes.
Emulation of the real User-agent header
In addition to the IP address, websites analyze other visitors' data, which can also complicate parsing. An important indicator that should not be forgotten when configuring software for crawling or parsing is the User-Agent http header.
User-Agent serves to identify the type of client software. From it, the web service server determines which browser, operating system and language the client uses. This data can be used to configure the access of search robots to sections of the site.
Most modern programs are customizable. For the successful collection of data from a particular site, it is recommended to set up a User-Agent emulating an ordinary user, that is, a real browser and current versions of the OS.
Fingerprint OS emulation
Some resources with more advanced user identification mechanisms can analyze the fingerprint of visitors, thereby more effectively combating unwanted parsers.
Fingerprint identification occurs as a result of analyzing the structure of TCP packages, which is quite difficult to fake. Therefore, to work with such mechanisms, it is best to use proxies that work on real mobile or residential devices, or that support the fingerprint spoofing function.
Mobile proxies from RSocks are launched on real smartphones with Android OS. Thus, they automatically have a fingerprint similar to ordinary users of the mobile web.
Private personal proxies work on dedicated servers, but at the same time they support the function of replacing the fingerprint OS. Thus, you can choose one of the available OS for your proxy.
Honeypot traps are used to identify search robots. Typically, this is a link in an HTML element that is invisible to regular users when viewing the page in a browser.
A regular user will not be able to follow the link, and the robot works with the entire HTML code of the page, which makes it possible to use this difference to block unwanted data collection.
This technology is not very widespread, but if you work with a service that uses it, you need to take this feature into account in your work.
Services for solving CAPTCHA
Websites using CAPTCHAs create additional complexities for automated access. However, there is a solution to this problem. Now on the net you can find services dealing with the CAPTCHA test solving.
Another way is to avoid the occurrence of CAPTCHAs when working with the site. This can be achieved by using clean and anonymous proxies and sending requests in a gentle manner that does not arouse the suspicion of user authentication algorithms.
Non-standard data collection algorithms
The sequence of following links within the same site is very important when scraping data. The transition algorithm should copy the actions of a real user of the service. This can be mouse movements, clicking on links, scrolling pages.
Clicking on links on a principle that does not correspond to the standard behavior of site visitors is likely to lead to blocking. Actions of a random nature that occur without any periodization will help to diversify the site navigation algorithm.
Reducing the request rate often helps to avoid blocking. Too frequent requests create an unnecessary load on the servers of the target site and look unlike the actions of a real user, so their source is likely to be blocked.
To reduce the intensity of requests, creating artificial pauses or using a large pool of proxies to redirect requests through different IP addresses can help.
In addition, it is important to choose the best time to collect data. It is best to run the procedure during the period when the load on the target service is the lowest. Typically, the periodization of the load depends on the specifics of the service and regional characteristics.
Images often have the greatest impact on the weight of web pages. Scraping images dramatically increases the amount of transmitted data, which significantly slows down the speed of the parsers and requires a large amount of memory to store the collected data.
Browser without GUI
Most of the time, non-graphical browsers are used for more economical and efficient data collection. These are the so-called headless browsers. Such a browser allows you to get full access to content on any site, but at the same time does not waste your server's resources on rendering them, which significantly speeds up the parsing process. All popular browsers (Firefox, Chrome, Edge, etc.) have versions without a graphical interface.
Following these guidelines will help improve the efficiency of data collection and significantly reduce the likelihood of blocking by the target web service. However, when considering each item, one should be guided by the specifics of the project, its internal logic.
More details about technologies for scraping and parsing data, including using Python, can be found in another article of our blog.