Question

Describe two major problems with screen scraping programs designed for the web or text based systems? Can these be overcome or mitigated in some way?

Answer 1

`Hey,

Note: Brother if you have any queries related the answer please do comment. I would be very happy to resolve all your queries.

Websites are free to choose whether they will allow web scrapers bots or not on their websites for data scraping purpose. There are websites that actually do not allow automated web scraping. This is mainly because, at most times these bots scrape data with the intention of gaining competitive advantage and drain the server resources of the website they are scraping from, thus adversely affecting site performance.

The main purpose of captchas are to separate humans from bots by displaying logical problems that humans find easy to solve but making it difficult on the bots. So, their basic job is to keep spam away. In presence of captcha, basic scraping scripts will tend to fail, but with new advancements, there are generally measures to subsist these captchas, in an ethical manner.

In order to keep up with the advancements in UI/UX and to add more features, websites undergo regular structural changes. The web scrapers are specifically written with respect to the code elements of the webpage at the point of setup, so, frequent changes complicates the codes, giving scrapers some sort of a hard time. Though every structural change will not affect the web scraper setup, but as any sort of change may result in data loss, it is recommended to keep a tab on the changes.

If a web scraper bot sends multiple parallel requests per second or unnaturally high no of requests, there’s a good chance that you will cross the thin line of ethical and unethical scrapping and get flagged and ultimately banned. If the web scraper is smart and has sufficient resources, they can carefully handle these kind of counter measures and make sure they stay at the right side of the law and still achieve what they want.

Real time data scraping can be of paramount importance to businesses as it supports immediate decision making. With the always fluctuating stock prices to the ever changing product prices in eCommerce, this can lead to huge capital gains for a business. But deciding what’s important and what’s not in real time is a challenge. Also, acquiring large data sets in real time is an overhead too. These real time web scrapers use a Rest API to monitor all dynamic data available in the public domain and scrape data in “nearly real time” ; but attaining the “holy grail” still remains a challenge.

There is a thin line between data collection and causing damage to the web by careless data scraping. As web scraping is a such an insightful tool and with the immense effect it has on businesses, web scraping should be done with responsibility. With a little respect we can keep a good thing going. Take a look at the best practices list for web scraping that we compiled.

These can be improved by the help of

[1] Respect the Robots.txt

A robots.txt file has all the information stored on the pages that a web scraper can crawl and pages that they cannot. Be sure to check the robots.txt file before you start with the scraping. If they have blocked bots altogether, its best to leave the site alone as its unethical to scrape the site in that scenario.

[2] Take care of the servers

It is very important to think about the acceptable frequency of requests and number of requests sent to the host server. Web servers are not flawless. They will crash if the load they can take is exceeded. Sending too many requests too soon can results in server failure and that creates a bad user experience for visitors on the website. While data scraping, keep a reasonable amount of gap between requests and try and keep the number of parallel requests in control.

[3] Don’t scrape during peak hours

Take it as a moral responsibility to scrape websites during non-peak periods, so that, visitors’ user experience is hampered in no way. This has a catch for the scraping business too : it will significantly improve the scraping speed.

[4] Use a headless browser

What is it? The Google blog says: “ It’s a way to run the Chrome browser in a headless environment. Essentially, running Chrome without chrome! “. These web browsers don’t have a GUI, but are executed via a command-line interface or using network communication. One definite advantage of using headless browsers is that they are faster than real browsers. Also, while using a headless browser, you don’t need to load a site fully, headless browser can just load the HTML portion and scrape, resulting into amore lightweight, resource saving and time saving scraping.

Kindly revert for any queries

Thanks.

Answer 2

Two Major Problems with Screen Scraping Programs (and Mitigation Strategies)

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1. Fragility Due to UI/Format Changes

• Problem:
  Screen scrapers rely on the structure of web pages or text outputs (e.g., HTML tags, positional text). Minor changes (e.g., redesigned UI, altered CSS classes) break the scraper.

• Example: A scraper targeting <div class="price"> fails if the class changes to <div class="product-price">.

• 
  

• Mitigation:

• Use robust selectors (e.g., XPath/CSS paths with wildcards or partial matches).

• Implement automated monitoring to detect failures (e.g., alerts when expected data fields are empty).

• Combine with APIs where available (more stable than scraping).

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2. Legal/Ethical Risks (Terms of Service Violations)

• Problem:
  Many websites prohibit scraping in their Terms of Service (ToS). Unauthorized scraping may trigger:

• IP bans (e.g., CAPTCHAs, rate limits).

• Legal action (e.g., hiQ Labs v. LinkedIn established some limits but risks remain).

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• Mitigation:

• Check robots.txt and ToS for scraping policies.

• Use public APIs (preferred) or request permission.

• Limit request rates (e.g., 1 request/second) to avoid detection.

• Anonymize requests via rotating proxies/user-agents.

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Bonus: Other Challenges & Fixes

• Data Quality Issues:

• Problem: Scraped data may be incomplete or noisy (e.g., ads mixed with content).

• Fix: Add data validation rules (e.g., regex filters, sanity checks).

• Dynamic Content (JavaScript):

• Problem: Traditional scrapers can’t render JS-heavy pages.

• Fix: Use headless browsers (e.g., Puppeteer, Selenium).

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