Web scraping has become a hot topic among people with rising demands for big data. More and more people hunger for data from multiple websites, and apply web scraping to collect wanted data. Because this data can help with their business development.
The process of scraping data from web pages can, however, not always be smooth. You might face many challenges while extracting data, such as IP blocking and CAPTCHA. Platform owners use such methods for anti-web-scraping, which can hinder you from getting data. In this article, let’s look at these challenges in detail and how web scraping tools can help to solve these problems.
General Challenges in Web Scraping
Bot Access
The first thing to check when your scraper does not work well is if your target website allows for scraping. You can check the Terms of Service (ToS) to learn about whether the website is available for scraping or unavailable via its robots.txt. Some platforms might need permission for web scraping. You can ask the web owner for access in such a situation and explain your scraping needs and purposes. To avoid any legal issues, it’s best to find an alternative site that has similar information if the owner does not accept your application.
Complicated and Fast-changing Website Structures
Most web pages are based on HTML (Hypertext Markup Language) files. However, designers and developers might have their own standards for building pages, so web page structures are widely divergent. As a result, when you need to scrape multiple websites even different pages on the same platform, you might need to build one scraper for each site.
And that’s not all. Websites periodically update their content or add new features to improve the user experience and loading speed which often leads to structural changes on the web pages. A previous scraper might not work for an updated page because web scrapers are set up according to the design of the page. Sometimes even a minor change in the target website will have an effect on the accuracy of the scraped data and require you to adjust the scraper.
Web scraping tools provide an easier alternative to writing scripts to extract data. Taking Octoparse as an example, it uses customized workflows to simulate human behaviors so as to deal with different pages. You can modify the scraper with a few clicks to adapt to the new pages, without rechecking HTML files and rewriting code.
IP Blocking
IP blocking is a widely used method to stop web scrapers from accessing the data of a website. Usually, this happens when a website detects a large number of requests coming from the same IP address. The website would either totally ban the IP or restrict its access to break down the scraping process.
Many IP proxy services allow people to obtain a continuously growing residential proxy pool ethically to fit any business needs, no matter the scale. Residential Proxies help companies optimize resources by producing noticeably fewer CAPTCHAs, IP blocks, or other obstacles. There are two common companies that provide IP proxy services: Luminati and Oxylabs.
For instance, Oxylabs offers 100M+ Residential Proxies from all around the world. Each residential proxy it provides is selected from a reliable source to ensure businesses won’t encounter any issues while gathering public data. The company offers location-based targeting at the country, city, and state levels and is best known for brand protection, market research, business intelligence, and ad verification. Oxylabs has a data center, Mobile, and SOCKS5 proxies, as well as a proxy manager and rotator. You can get a 7-day free trial to test their service or pay as you go starting at $15/GB.
When it comes to web scraping tools, Octoparse provides several cloud servers for Cloud Extraction to cope with IP blocking. When your task runs with Cloud Extraction, you can take advantage of multiple using Octoparse’s IPs. Then you can avoid using only one IP to request too many times but keep the high speed.
CAPTCHA
CAPTCHA, short for Completely Automated Public Turing Test to Tell Computers and Human Apart, is often used to separate humans from scraping tools by displaying images or logical problems that humans find easy to solve but scrapers don’t.
Nowadays, many CAPTCHA solvers can be implemented into bots to ensure non-stopping scrapers. Octoparse can currently handle ReCaptcha V2 and ImageCaptcha to improve the efficiency of web scraping. However, although the technologies to overcome CAPTCHA can help acquire continuous data feeds, they could still slow down the scraping process.
Honeypot Traps
A honeypot is a trap the website owner puts on the page to catch web scrapers. The traps can be elements or links that are invisible to humans but visible to scrapers. If a scraper accesses such elements and falls into the trap, the website can block that scraper using the IP address it receives.
Octoparse uses XPath to precisely locate items for clicking or scraping. With the help of XPath, the scraper can distinguish the wanted data fields from honeypot traps and reduce the chance of catching by the traps.
Slow and Unstable Loading Speed
Websites may respond slowly or even fail to load when receiving too many access requests. This is not a problem when humans browse the site as they just need to reload the page and wait for it to recover. But things change when it comes to web scraping. The scraping process may be broken up as the scraper does not know how to deal with such an emergency. So that users may need to give the scraper an instruction to retry manually.
Or, you can choose to add an extra action while building a scraper. Octoparse now allows users to set up an auto-retry or retry loading when certain conditions are met to resolve the issue. You can even execute customized workflows under preset situations.
Dynamic Content
Many websites apply AJAX (asynchronous JavaScript and XML) to update dynamic web content. Examples are lazy loading images, infinite scrolling, and showing more info by clicking a button via AJAX calls. It is convenient for users to view more information without refreshing the websites and missing all the previous content on the page. But for web scrapers, it can be a challenge. If a web scraper cannot recognize AJAX, it might fail to collect data or gain duplicate content.
To handle AJAX, Octoparse allows users to set up an AJAX timeout for the “Click item” or “Click to Paginate” to tell Octoparse to go to the next action when the timeout is reached. After that, you can easily get a scraper that can scrape pages with AJAX or scrolling.
Login Requirements
When you browse a website, some protected information may require you to log in first. Once you submit your login credentials, your browser will automatically append the cookie value to multiple requests you make your way to most sites, so the websites know you’re the same person who just logged in earlier. Similarly, when you use a web scraper to pull data from a website, you might need to log in with your account to access the wanted data. In this term, be sure that cookies have been sent with the requests. Octoparse can simply help users scrape website data behind a login, and save the cookies, just like a browser does.
Real-time Data Scraping
Scraping data in real-time is essential for price comparisons, competitor monitoring, inventory tracking, etc. The data can change in the blink of an eye and may lead to huge capital gains for a business. The scraper needs to monitor the websites all the time and extract the latest data. However, it is hard to avoid some delays as the request and data delivery will take time, not to mention acquiring a large amount of data in real-time is a time-consuming and heavy workload task for most web scrapers.
Octoparse has cloud servers that allow users to schedule their web scraping tasks at a minimum interval of 5 minutes to achieve nearly real-time scraping. After setting a scheduled extraction, Octoparse will launch the task autocratically to collect the up-to-date information instead of requiring users to click the Start button again and again, which will surely contribute to the working efficiency.
Wrap-up
Besides the challenges we mentioned in this post, there are certainly more challenges and limitations in web scraping. But there is a universal principle for scraping: treat the websites nicely and do not try to overload them. If you are looking for a more smooth and efficient web scraping experience, you can always find a web scraping tool or service to help you handle the scraping job. Try Octoparse now, and bring your web scraping to the next level!
