Data Scraping Services - Things to take care while doing Web Scraping!!!

In the present day and age, web scraping word becomes most popular in data science. Basically web scraping is extracting the information from the websites using pre-written programs and web scraping scripts. Many organizations have successfully used web site scraping to build relevant and useful database that they use on a daily basis to enhance their business interests. This is the age of the Big Data and web scraping is one of the trending techniques in the data science.

Throughout my journey of learning web scraping and implementing many successful scraping projects, I have come across some great experiences we can learn from.  In this post, I’m going to discuss some of the approaches to take and approaches to avoid while executing web scraping.

User Proxies: Anonymously scraping data from websites

One should not scrape website with a single IP Address. Because when you repeatedly request the web page for web scraping, there is a chance that the remote web server might block your IP address preventing further request to the web page. To overcome this situation, one should scrape websites with the help of proxy servers (anonymous scraping). This will minimize the risk of getting trapped and blacklisted by a website. Use of Proxies to hide your identity (network details) to remote web servers while scraping data. You may also use a VPN instead of proxies to anonymously scrape websites.

Take maximum data and store it.

Do not follow “process the web page as it comes from the remote server”. Instead take all the information and store it to disk. This approach will be useful when your scraping algorithm breaks in the middle. In this case you don’t have to start scraping again. Never download the same content more than once as you are just wasting bandwidth. Try and download all content to disk in one go and then do the processing.

Follow strict rules in parsing:

Check various rules while parsing the information from the web site. For example if you expect a value to be a date then check that it’s really a date. This may greatly improve the quality of information. When you get unexpected data, then the algorithm need to be changed accordingly.

Respect Robots.txt

Robots.txt specifies the set of rules that should be followed by web crawlers and robots. I strongly advise you to consider and adjust your crawler to fully respect robots.txt. Robots.txt contains instructions on the exact pages that you are allowed to crawl, user-agent, and the requisite intervals between page requests. Following to these instructions minimizes the chance of getting blacklisted and banned from website owner.

Use XPath Smartly

XPath is a nice option to select elements of the HTML document more flexibly than CSS Selectors.  Be careful about HTML structure change through page to page so one xpath you made may be failed to extract data on another page due to changes in HTML structure.

Obey Website TOC:

Some websites make it absolutely apparent in their terms and conditions that they are particularly against to web scraping activities on their content. This can make you vulnerable against possible ethical and legal implications.

Test sample scrape and verify the data with actual scrape

Once you are done with web scraping project set up, you need to test it for sometimes. Check the extracted data. If something is not good, find out the cause and make changes accordingly and finally come to a perfect web scraping project.

Source: http://webdata-scraping.com/things-take-care-web-scraping/

Data Mining Services

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Based on your requirements, we can mine data from your preferred data sources, or we will use our own reliable sources to mine the data required by you. We have been using automated as well manual data mining strategies to deliver superior data mining services.

Types of data mining services delivered by us

With an extensive variety of data mining services provided by us, you will definitely be able to find the most perfect service package to cater to your requirements. Below listed are just some of the data mining services offered by us:

•    Web data mining
•    Data extraction
•    Data capture
•    Data gathering
•    Collection of required data
•    Validation of data

Outsource data mining requirements to us, and we are sure that the data mining India unit of Hi-Tech BPO Services will be able to formulate the most appropriate and cost effective solutions to include your entire requirements.

Highlights of our data mining services:

•    Most affordable rates
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•    Latest data mining technologies used to mine all required data
•    Data will be mined, gathered, processed and validated as per your requirements
•    Mined data can be directly included into your database

Competitive advantage of using our data mining services

To mine accurate and relevant data, some level of internet knowledge is essential. And it would also consume a lot of your valuable time. With our data mining services, we will take care of all your data mining tasks, while you look after your business and its core functions.

The affordably priced data mining services delivered by the data mining India unit will also help you to save considerable amount of your money, which you can put into more productive purposes.

Source: http://www.hitechbposervices.com/data-mining.php

Data Scraping - One application or multiple?

I have 30+ sources of data I scrape daily in various formats (xml, html, csv). Over the last three years Ive built 20 or so c# console applications that go out, download the data and re-format it into a database. But Im curious what other people are doing for this type of task. Are people building one tool that has a lot of variables and inputs or are people designing 20+ programs to scrape and parse this data. Everything is hard-coded into each console and run through Windows Task Manager.

Added a couple additional thoughts/details:

    Of the 30 sources, they all have unique properties, all are uploaded into individual MySQL tables and all have varying frequencies. For example, one data source is hit once a minute, another on 5 minute intervals. Majority are once an hour and once a day.

At current I download the formats (xml, csv, html), parse them into a formatted csv and put them into staging folders. Within that folder, I run an application that reads a config file specific to the folder. When a new csv is added to the folder, the application then uploads the data into the specific MySQL tables designated in the config file.

Im wondering if it is worth re-building all this into a larger complex program that is more capable of dynamically adding content+scrapes and adjusting to format changes.

Looking for outside thoughts.

5 Answers

What you are working on is basically ETL. So at a high level you need an export component (get stuff) a transform component (map to known format) and a load (take known format and put stuff somewhere). If you are comfortable being tied to a RDBMS you could use something like SQL Server SSIS packages. What I would do is create a host application that managed common aspects of the overall process (errors, and pipeline processing). Then make the specifics of the E, T, and L pluggable. A low ceremony way to get this would be to host the powershell runtime and create each seesion with common context objects that the scripts will use to communicate. You get a built in pipe and filter model for scripts and easy, safe extensibility. This design has worked extremely for my team with a similar situation.

Resist the temptation to rewrite.

However, for new code, you could plan for what you know has already happened. Write a retrieval mechanism that you can reuse through configuration. Write a translation mechanism that you can reuse (maybe in a library that you can call with very little code). Write a saving mechanism that can be called or configured.

At this point, you've written #21(+). Now, the following ones can be handled with a tiny bit of code and configuration. Yay!

(You may want to implement this in a service that handles multiple conversions, but weight the benefits of it versus the ability to separate errors in one module from the rest.)

1

It depends - if you need the scrapers to feed into a single application/database and have a uniform data format, it makes sense to have them all in a single program (possibly inheriting from a common base scraper).

If not and they are completely unrelated to each other, might as well keep them separate so changes in one have no effect on another.

Update, following edits to question:

Don't change things just for the sake of change. You have something that works, don't mess with it too much.

Since your data sources and data sinks are all separate from each other, combining them into one application will simply create a very complicated application that will be very difficult to change when needed.

Since the scrapers are separate, keep the separation as you have it now.

As sbrenton said, this most falls in with ETL. You should check out Talend Open Studio. It specializes in handling data flows like I imagine yours are as well as other things like duplicate removal, normalization of fields; tens/hundreds of drag and drop ETL components, you can also write custom code as Talend is a code generator as well, either Java or Perl are options. You can also use Talend to execute system commands. I use it for my ETL work, although not in production, in production we will use SSIS, mostly due to lots of other Microsoft products in house.

You may want to use some good scheduling library, like Quartz.NET.

In a few words, here's what you can expect:

    Your tasks are represented by classes and not processes

    You can set and forget tasks and scale across multiple servers

    You have an out-of-the-box system to actually take care of what is needed to be run when, what failed and needs to be re-run, etc. etc.

Source: http://programmers.stackexchange.com/questions/118077/data-scraping-one-application-or-multiple/118098#118098

How to prevent getting blacklisted while scraping

Crawlers can retrieve data much quicker and in greater depth than human searchers, so bad scraping practices can have some impact on the performance of the site.

Needless to say, if a single crawler is performing multiple requests per second and/or downloading large files, a under powered server would have a hard time keeping up with requests from multiple crawlers.

Since spiders don’t bring direct organic traffic and seemingly affect the performance of the site, most site admins hate spiders and do their best to prevent them.

Lets go through how websites detect and block spiders and also know the techniques to overcome those barriers.

Most websites don’t have anti scraping mechanisms since it would affect the user experience, but some sites do not believe in open data access.

Before going through this article always keep in mind that

    A GOOD SPIDER MUST OBEY A WEBSITE’S CRAWLING POLICIES.

HOW DOES DETECTING ‘SPIDER ACTIVITY’ WORK?

A web server can use different mechanisms to detect a spider from a normal user. Here are some methods used by a site to detect a spider:

•    Unusual traffic/high download rate especially from a single client/or IP address within a short time span raises a bot alert.

•    Repetitive tasks done on website based on an assumption that a human user won’t perform the same repetitive tasks all the time.

•    The site has honeypot traps inside their pages, these honeypots are usually links which aren’t visible to a normal user but only to a spider . When a scraper/spider tries to access the link, the alarms are tripped.

Spend some time and investigate the anti-scraping mechanisms used by a site and build the spider accordingly, it will provide a better outcome in the long run and increase the longevity and robustness of your work.

EASIEST WAY TO FIND IF A SITE HATES BOTS

Check the robots.txt file if it contains line like these, It means the site doesn’t like bots. However, since most sites want to be on Google (arguably the largest scraper of websites globally ;-)) they do allow access to bots and spiders.

User-agent: *
Disallow: /

This line is for preventing well-behaved bots or the bots which respect robots.txt.

Another way is CAPTCHAs irritating presence in the sites other than in authentication page.

WHAT HAPPENS WHEN YOU GET BANNED

There are two ways to ban a webspider, either by banning all accesses from a particular IP or by banning all accesses that use a specific id to access the server (most browsers and web spiders identify themselves whenever they request a page by user agents. Chrome browser for example uses Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.149 Safari/537.36

The banning can be temporary or permanent. Temporary blocks can last minutes or hours.

HOW DO WE KNOW A SITE HAS BLOCKED US?

If any of the following symptoms appear on the site that you are crawling, it is a sign of being blocked or banned.

•    Showing CAPTCHA pages
•    Unusual content delivery delay
•    Frequent response with 404,301,500 errors,

also frequent appearance of these status codes are also indication of blocking.

•    401 Unauthorized
•    403 Forbidden
•    404 Not Found
•    408 Request Timeout
•    429 Too Many Requests

WEB CRAWLING BEST PRACTICES

These are the best practices we can follow to overcome the detection.

1. MAKE CRAWLING SLOWER, DO NOT DDoS THE SERVER, TREAT THEM NICELY

Use auto throttling mechanisms, which will automatically throttle crawling speed based on the load on both spider and the website, you are crawling and also adjust the spider to optimum crawling speed. The faster you crawl, the worse it is for everyone.

Put some random sleeps in between requests, Add some delays after crawled number of pages. Choose the lowest number of concurrent requests possible. These techniques make the spider looks like a human being.

2. DISGUISE YOUR REQUESTS BY ROTATING IP/PROXY

A server can easily detects a bot by checking the requests from a single IP address, So we use different IPs for making request to a server and detection rate become lesser. Make a pool of IPs that you can use and use random ones for each request.

There are several methods can be used to change the IP. Services like VPN ,shared proxies, TOR can help  and some third parties are also provides services for IP rotation.

3. USER-AGENT SPOOFING

Since every request made from a client end contains a user-agent header ,Using the same useragent multiple times leads to the detection of a bot. User agent spoofing is the best solution for this. Spoof the User agent by making a list of user agents and pick a random one for each request.

Websites do not want to block genuine users so you should try to look like one. Set your user-agent to a common web browser instead of using the library default (such as wget/version or urllib/version). You could even pretend to be the Google Bot: Googlebot/2.1; (http://www.google.com/bot.html)

You can check your user-agent string here:

http://www.whatsmyuseragent.com/

A good user-agent string list can be found here:

http://www.useragentstring.com/pages/useragentstring.php

4. BE AWARE OF HONEYPOTS

Some site designers put honeypot traps inside websites to detect web spiders, They may be links that normal user can’t see and a spider can.

When following links always take care that the link has proper visibility with no nofollow tag. Some honeypot links to detect spiders will be have the CSS style display:none or will be color disguised to blend in with the page’s background color.

5. DO NOT ALWAYS FOLLOW THE SAME CRAWLING PATTERN

Only robots follow the same crawling pattern,Sites that have intelligent anti-crawling mechanisms can easily detect spiders from finding pattern in their actions. Humans wont perform repetitive tasks a lot of times. Incorporate some random clicks on the page, mouse movements and random actions that will make a spider looks like a human client.

6. ALWAYS RESPECT THE robots.txt

All web spiders are supposed to follow rules that you place in a robots.txt file in a website, such as how frequently they are allowed to request pages, and from what directories they are allowed to crawl through. They should also be supplying a consistent valid User-Agent string that identifies the requests as a bot request.

Source: http://learn.scrapehero.com/how-to-prevent-getting-blacklisted-while-scraping/

The Features of the "Holographic Meridian Scraping Therapy"

1. Systematic nature: Brief introduction to the knowledge of viscera, meridians and points in traditional Chinese medicine, theory of holographic diagnosis and treatment; preliminary discussion of the treatment and health care mechanism of scraping therapy; systemat­ic introduction to the concrete methods of the holographic meridian scraping therapy; enumerating a host of therapeutic methods of scraping for disorders in both Chinese and Western medicine to em­body a combination of disease differentiation and syndrome differen­tiation; and summarizing the health care scraping methods. It is a practical handbook of gua sha.

2. Scientific: Applying the theories of Chinese and Western medicine to explain the health care and treatment mechanism and clinical applications of scraping therapy; introducing in detail the practical manipulations, items for attention, and indications and contraindications of the scraping therapy. Here are introduced repre­sentative diseases in different clinical departments, for which scrap­ing therapy has a better curative effect and the therapeutic methods of scraping for these diseases. Stress is placed on disease differentia­tion in Western medicine and syndrome differentiation in Chinese medicine, which should be combined in practical application.

Although there are more than 140,000 kinds of disease known to modem medicine, all diseases are related to dysfunction of the 14 meridians and internal organs, according to traditional Chinese med­icine. The object of scraping therapy is to correct the disharmony in the meridians and internal organs to recover the normal bodily func­tions. Thus, the scraping of a set of meridian points can be used to treat many diseases. In the section on clinical application only about 100 kinds of common diseases are discussed, although the actual number is much more than that. For easy reference the "Index of Diseases and Symptoms" is appended at the back of the book.

3. Practical: Using simple language and plenty of pictures and diagrams to guarantee that readers can easily leam, memorize and apply the principles of scraping therapy. As long as they master the methods explained in Chapter Three, readers without any medical knowledge can apply scraping therapy to themselves or others, with reference to the pictures in Chapters Four and Five. Besides scraping therapy, herbal treatment for each disease or syndrome is explained and may be used in combination with the scraping techniques.

Referring to the Holographic Meridian Hand Diagnosis and pic­tures at the back of the book will enhance accuracy of diagnosis and increase the effectiveness of scraping therapy.

Since the first publication and distribution of the Chinese edition of the book in July 1995, it has been welcomed by both medical specialists and lay people. In March 1996 this book was republished and adopted as a textbook by the School for Advanced Studies of Traditional Chinese Medicine affiliated to the Institute of the Acu­puncture and Moxibustion of the China Academy of Traditional Chi­nese Medicine.

In order to bring this health care method to more and more peo­ple and to make traditional Chinese medicine better appreciated They have modified and replenished this book in the spirit of constant im­provement. They hope that they may make a contribution to the health care of mankind with this natural therapy which has no side-effects and causes no pollution.

They hope that the Holographic Meridian Scraping Therapy can help the health and happiness of more and more families in the world.

Source: http://ezinearticles.com/?The-Features-of-the-Holographic-Meridian-Scraping-Therapy&id=5005031

Web Scraping Services Are Important Tools For Knowledge

Data extraction and web scraping techniques are important tools to find relevant data and information for personal or business use. Many companies, self-employed to copy and paste data from web pages. This process is very reliable, but very expensive as it is a waste of time and effort to get results. This is because the data collected and spent less resources and time required to collect these data are compared.

At present, several mining companies and their websites effective web scraping technique specifically for the thousands of pages of information developed culture can be traced. The information from a CSV file, database, XML file, or any other source with the required format is alameda. understanding of correlations and patterns in the data, so that policies can be designed to assist decision making. The information can also be stored for future reference.

The following are some common examples of data extraction process:

In order to rule through a government portal, citizens who are reliable for a given survey name removed.

Competitive pricing and data products include scraping websites

To access the web site or web design Stock download the videos and photos of scratching

Automatic Data Collection

It regularly collects data on a regular basis. Automated data collection techniques are very important because they find the company’s customer trends and market trends to help. By determining market trends, it is possible to understand customer behavior and predict the likelihood of the data will change.

The following are some examples of automated data collection:

Monitoring of special hourly rates for stocks

collects daily mortgage rates from various financial institutions

on a regular basis is necessary to check the weather

By using web scraping services, you can extract all data related to your business. Then analyzed the data to a spreadsheet or database can be downloaded and compared. Storing data in a database or in a required format and interpretation of the correlations to understand and makes it easier to identify hidden patterns.

Data extraction services, it is possible pricing, email, databases, profile data, and consistently to competitors for information about the data. Different techniques and processes designed to collect and analyze data, and has developed over time. Web Scraping for business processes that have beaten the market recently is one. It is a process from various sources such as websites and databases with large amounts of data provides.

Some of the most common methods used to scrape web crawling, text, fun, DOM analysis and include matching expression. After the process is only analyzers, HTML pages or meaning can be achieved through annotations. There are many different ways of scaling data, but more importantly is working toward the same goal. The main purpose of using web scraping service to retrieve and compile data in databases and web sites. In the business world is to remain relevant to the business process.

The central question about the relevance of web scraping contact. The process is relevant to the business world? The answer is yes. The fact that it is used by large companies in the world and many awards speaks derivatives.

Source: http://www.selfgrowth.com/articles/web-scraping-services-are-important-tools-for-knowledge