Scraping a website from a windows service

Question

Hi there.  I have a windows forms application that scrapes a website to retrieve some data.  I would like to implement the same functionality as a windows service.  The reason for this is to allow the program to run 24/7 without  having a user signed in. 

To that end, my current version of the program uses a web browser control (system.windows.forms.webbrowser) to navigate the pages, click the buttons, allow scripts to do their thing, etc.  I cannot figure out a way to do the same without the web browser control, but the web browser control cannot be instantiated in a windows service (because there is no user interface in a web service).

Does anyone have any brilliant ideas on how to get around this?

Thank you very much!

Answers

Hi Andy,

There is a tool which could let you manipulate anything you want on the website. This agile HTML parser builds a read/write DOM and supports plain XPATH or XSLT. It is a .NET code library that allows you to parse "out of the web" HTML files. The parser is very tolerant with "real world" malformed HTML. The object model is very similar to what proposes System.Xml, but for HTML documents (or streams). More information, please check:

http://htmlagilitypack.codeplex.com/

Have a nice day.

Best regards

All replies

You are not telling if you are using a .NET Express edition or not

You are not telling which Framework

You are not realy saying what data you are getting from the web site.

So

I made an example of service that work on any Studio edition (including the Express)

to install it, I supposed that you have at least the Framework2, so you will use something similar to:

    %SystemRoot%\Microsoft.NET\Framework\v2.0.50727\installutil /i C:\Test\MyWindowService\MyWindowService\bin\Release\MyWindowService.exe

In the example, I supposed that you are downloading some file from the site

You will need a reference to Windows.Form for the timer


Imports System.ServiceProcess

Imports System.Configuration.Install

Public Class WindowsService : Inherits ServiceBase

  Private Minute As Integer = 60000

  Private WithEvents Timer As New Timer With {.Interval = 30 * Minute, .Enabled = True}

  Public Sub New()

    Me.ServiceName = "MyService"

    Me.EventLog.Log = "Application"

    Me.CanHandlePowerEvent = True

    Me.CanHandleSessionChangeEvent = True

    Me.CanPauseAndContinue = True

    Me.CanShutdown = True

    Me.CanStop = True

  End Sub


  Private Sub Timer_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Timer.Tick

    If IO.File.Exists("C:\MyPath.Data") Then IO.File.Delete("C:\MyPath.Data")

    My.Computer.Network.DownloadFile("http://MyURL.com", "C:\MyPath.Data", "MyUserName", "MyPassword")

    'Do Something with the data downloaded

  End Sub

End Class

<Microsoft.VisualBasic.HideModuleName()> _

Module MainModule

  Public TheServiceName As String

  Public Sub main()

    Dim TheServiceApplication As New WindowsService

    TheServiceName = TheServiceApplication.ServiceName

    ServiceBase.Run(TheServiceApplication)

  End Sub

End Module

<System.ComponentModel.RunInstaller(True)> _

Public Class WindowsServiceInstaller : Inherits Installer

  Public Sub New()

    Dim serviceProcessInstaller As ServiceProcessInstaller = New ServiceProcessInstaller()

    Dim serviceInstaller As ServiceInstaller = New ServiceInstaller()

    serviceProcessInstaller.Account = ServiceAccount.LocalSystem

    serviceProcessInstaller.Username = Nothing

    serviceProcessInstaller.Password = Nothing

    serviceInstaller.DisplayName = "My Windows Service"

    serviceInstaller.StartType = ServiceStartMode.Automatic

    serviceInstaller.ServiceName = TheServiceName

    Me.Installers.Add(serviceProcessInstaller)

    Me.Installers.Add(serviceInstaller)

  End Sub

End Class



 Hello Andy,

Thanks for your post.

What do you want to scrape from the page? HttpWebRequest class ans WebClient class may be what you need. More information, please check:

The HttpWebRequest class provides support for the properties and methods defined in WebRequest and for additional properties and methods that enable the user to interact directly with servers using HTTP.

http://msdn.microsoft.com/en-us/library/system.net.httpwebrequest.aspx

The WebClient class provides common methods for sending data to or receiving data from any local, intranet, or Internet resource identified by a URI

http://msdn.microsoft.com/en-us/library/system.net.webclient.aspx

If you have any concenrs, please feel free to follow up.

Best regards



Hi Andy,

What about this problem on your side now? If you have any concerns, please feel free to follow up.

Have a nice day.

Best regards



Hi Andy,

When you come back, if you need further assistance about this issue, please feel free to let us know. We will continue to work with this issue.

Have a nice day.

Best regards



Thank you for the reply. Sorry it has taken me so long to respond.  I did not receive any notification that someone had replied!

I am using Visual Studio 2010 Ultimate Edition and the .NET framework 4.0.  Actually, I am upgrading some old code written in VB 6.0, but I can use the latest and greatest thats available.

The application uses a browser control to go to the page, fill in values, click on UI elements, read the HTML that returns, etc.  The purpose of the application is to collection useful information regularily/automatically.

I know how to create a web service, but using the web control in such a service is problematic because the web browser control was meant to be placed on a windows form.  I am not able to create a new instance of it in a project designated as a windows service.



Andy

Thank you for the reply. Sorry it has taken me so long to respond.  I did not receive any notification that someone had replied!

I thought a web request was for web services (retrieving information from them).  I am trying to retreive useful information from a website designed for interaction by a human, such as selecting items from lists and clicking buttons.   I currently use a web browser control to programmatically do what a person would do and get the pages back which in turn get parsed.

Andy



Hi Andy,

There is a tool which could let you manipulate anything you want on the website. This agile HTML parser builds a read/write DOM and supports plain XPATH or XSLT. It is a .NET code library that allows you to parse "out of the web" HTML files. The parser is very tolerant with "real world" malformed HTML. The object model is very similar to what proposes System.Xml, but for HTML documents (or streams). More information, please check:

http://htmlagilitypack.codeplex.com/

Have a nice day.

Best regards



Thanks for the suggestion.  I will go to that link and see if it will work.  I will update this post with what I find.

I am writing to check the status of the issue on your side. Would you mind letting us know the result of the suggestions? If you have any concerns, please feel free to follow up.

Have a nice day.



Best regards

Hi Liliane

Thank for the follow up reply.  I don't have an answer as of yet.  Implementing this is going to take time and I haven't been given the go-ahead by my boss to spend the time to pursue it.



Hi Andy,

Never minde. You could have a try when you feel free. If you have any further questions about this issue, please feel free to let us know. We will continue to work with you on this issue.

Have a nice day.

Best regards

Source: https://social.msdn.microsoft.com/Forums/vstudio/en-US/f5d565b1-236b-43c2-90c7-f5cc3b2c341b/scraping-a-website-from-a-windows-service

Data Mining and Market Research

Online market research attributes to success and growth of many businesses. Online market research in simple terms we can say it is the learning of current and the latest market situations which involve surveys, web and data mining modules. To date research by use of the internet it is very important since it depends on data gathered from internet services and then one can recognize that market research keeps the business successful.

A number of managers in small businesses have a mental deem in that online market research is obligatory to big or larger companies. For true you will understand that whether the businesses is medium, large or small actually need online marketing research and this is a reason why the significance of the process and allegation will approve the targeted and potential clients. In this case Data mining progression is employed to streamline on what targeted and potential clientele needs. Areas where data mining is used:

Preferences. In any given service or product, you will learn what a customer looking for and how your product or service is different from other competitors. By use of Data mining you will be able to determine the customer preferences and you will be able to modify your services and products meet the customer choice.

Buying patterns. What is known and created for purchasing patterns from different customers. A situation can be that customers try to spend a lot on certain products and little on others. But through Data mining it is easy to understand such purchasing patterns and finally plan the appropriate techniques to be used in the marketing.

Prices. To find out whether the company is selling its products to the clients or not prices are the key factors to take into account. One should understand on the right selling price of the products. Web scrapping is easier to find the suitable pricing.

Source: http://www.loginworks.com/blogs/web-scraping-blogs/data-mining-market-research/

Some Traps to know and avoid in Web Scraping

In the present day and age, web scraping comes across as a handy tool in the right hands. In essence, web scraping means quickly crawling the web for specific information, using pre-written programs. Scraping efforts are designed to crawl and analyze the data of entire websites, and saving the parts that are needed. Many industries have successfully used web scraping to create massive banks of relevant, actionable data that they use on a daily basis to further their business interests and provide better service to customers. This is the age of the Big Data, and web scraping is one of the ways in which businesses can tap into this huge data repository and come up with relevant information that aids them in every way.

Web scraping, however, does come with its own share of problems and roadblocks. With every passing day, a growing number of websites are trying to actively minimize the instance of scraping and protect their own data to stay afloat in today’s situation of immense competition. There are several other complications which might arise and several traps that can slow you down during your web scraping pursuits. Knowing about these traps and how to avoid them can be of great help if you want to successfully accomplish your web scraping goals and get the amount of data that you require.

Complications in Web Scraping

Over time, various complications have risen in the field of web scraping. Many websites have started to get paranoid about data duplication and data security problems and have begun to protect their data in many ways. Some websites are not generally agreeable to the moral and ethical implications of web scraping, and do not want their content to be scraped. There are many places where website owners can set traps and roadblocks to slow down or stop web scraping activities. Major search engines also have a system in place to discourage scraping of search engine results. Last but not the least, many websites and web services announce a blanket ban on web scraping and say the same in their terms and conditions, potentially leading to legal issues in the event of any scraping.

Here are some of the most common complications that you might face during your web scraping efforts which you should be particularly aware about –

•    Some locations on the intranet might discourage web scraping to prevent data duplication or data theft.

•    Many websites have in place a number of different traps to detect and ban web scraping tools and programs.

•    Certain websites make it clear in their terms and conditions that they consider web scraping an infringement of their privacy and might even consider legal redress.

•    In a number of locations, simple measures are implemented to prevent non-human traffic to websites, making it difficult for web scraping tools to go on collecting data at a fast pace.

To surmount these difficulties, you need a deeper and more insightful understanding of the way web scraping works and also the attitude of website owners towards web scraping efforts. Most major issues can be subverted or quietly avoided if you maintain good working practice during your web scraping efforts and understand the mentality of the people whose sites you are scraping.

Common Problems

With automated scraping, you might face a number of common problems. The behavior of web scraping programs or spiders presents a certain picture to the target website. It then uses this behavior to distinguish between human users and web scraping spiders. Depending on that information, a website may or may not employ particular web scraping traps to stop your efforts. Some of the commonly employed traps are –

Crawling Pattern Checks – Some websites detect scraping activities by analyzing crawling patterns. Web scraping robots follow a distinct crawling pattern which incorporates repetitive tasks like visiting links and copying content. By carefully analyzing these patterns, websites can determine that they are being caused by a web scraping robot and not a human user, and can take preventive measures.

Honeypots – Some websites have honeypots in their webpages to detect and block web scraping activities. These can be in the form of links that are not visible to human users, being disguised in a certain way. Since your web crawler program does not operate the way a human user does, it can try and scrape information from that link. As a result, the website can detect the scraping effort and block the source IP addresses.

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

Infinite Loops – Your web scraping program can be tricked into visiting the same URL again and again by using certain URL building techniques.

These traps in web scraping can prove to be detrimental to your efforts and you need to find innovative and effective ways to surpass these problems. Learning some web crawler tips to avoid traps and judiciously using them is a great way of making sure that your web scraping requirements are met without any hassle.

What you can do

The first and foremost rule of thumb about web scraping is that you have to make your efforts as inconspicuous as possible. This way you will not arouse suspicion and negative behavior from your target websites. To this end, you need a well-designed web scraping program with a human touch. Such a program can operate in flexible ways so as to not alert website owners through the usual traffic criteria used to spot scraping tools.

Some of the measures that you can implement to ensure that you steer clear of common web scraping traps are –

•    The first thing that you need to do is to ascertain if a particular website that you are trying to scrape has any particular dislike towards web scraping tools. If you see any indication in their terms and conditions, tread cautiously and stop scraping their website if you receive any notification regarding their lack of approval. Being polite and honest can help you get away with a lot.

•    Try and minimize the load on every single website that you visit for scraping. Putting a high load on websites can alert them towards your intentions and often might cause them to develop a negative attitude. To decrease the overall load on a particular website, there are many techniques that you can employ.

•    Start by caching the pages that you have already crawled to ensure that you do not have to load them again.

•    Also store the URLs of crawled pages.

•    Take things slow and do not flood the website with multiple parallel requests that put a strain on their resources.

•    Handle your scraping in gentle phases and take only the content you require.

•    Your scraping spider should be able to diversify its actions, change its crawling pattern and present a polymorphic front to websites, so as not to cause an alarm and put them on the defensive.

•    Arrive at an optimum crawling speed, so as to not tax the resources and bandwidth of the target website. Use auto throttling mechanisms to optimize web traffic and put random breaks in between page requests, with the lowest possible number of concurrent requests that you can work with.

•    Use multiple IP addresses for your scraping efforts, or take advantage of proxy servers and VPN services. This will help to minimize the danger of getting trapped and blacklisted by a website.

•    Be prepared to understand the respect the express wishes and policies of a website regarding web scraping by taking a good look at the target ‘robots.txt’ file. This file contains clear instructions on the exact pages that you are allowed to crawl, and the requisite intervals between page requests. It might also specify that you use a pre-determined user agent identification string that classifies you as a scraping bot. adhering to these instructions minimizes the chance of getting on the bad side of website owners and risking bans.

Use an advanced tool for web scraping which can store and check data, URLs and patterns. Whether your web scraping needs are confined to one domain or spread over many, you need to appreciate that many website owners do not take kindly to scraping. The trick here is to ensure that you maintain industry best practices while extracting data from websites. This prevents any incident of misunderstanding, and allows you a clear pathway to most of the data sources that you want to leverage for your requirements.

Hope this article helps in understanding the different traps and roadblocks that you might face during your web scraping endeavors. This will help you in figuring out smart, sensible ways to work around them and make sure that your experience remains smooth. This way, you can keep receiving the important information that you need with web scraping. Following these basic guidelines can help you prevent getting banned or blacklisted and stay in the good books of website owners. This will allow you continue with your web scraping activities unencumbered.

Source: https://www.promptcloud.com/blog/some-traps-to-avoid-in-web-scraping/

The Coal Mining Industry And Investing In It

The History Of Coal Usage

Coal was initially used as a domestic fuel, until the industrial revolution, when coal became an integral part of manufacturing for creating electricity, transportation, heating and molding purposes. The large scale mining aspect of coal was introduced around the 18th century, and Britain was the first nation to successfully use advanced coal mining techniques, which involved underground excavation and mining.

Initially coal was scraped off the surface by different processes like drift and shaft mining. This has been done for centuries, and since the demand was quite low, these mining processes were more than enough to accommodate the demand in the market.

However, when the practical uses of using coal as fuel sparked industrial revolution, the demand for coal rose abruptly, leading to severe shortage of the coal output, gradually paving the way for new ways to extract coal from under the ground.

Coal became a popular fuel for all purposes, even to this day, due to their abundance and their ability to produce more energy per mass than other conventional solid fuels like wood. This was important as far as transportation, creating electricity and manufacturing processes are concerned, which allowed industries to use up less space and increase productivity. The usage of coal started to dwindle once alternate energies such as oil and gas began to be used in almost all processes, however, coal is still a primary fuel source for manufacturing processes to this day.

The Process Of Coal Mining

Extracting coal is a difficult and complex process. Coal is a natural resource, a fossil fuel that is a result of millions of years of decay of plants and living organisms under the ground. Some can be found on the surface, while other coal deposits are found deep underground.

Coal mining or extraction comes broadly in two different processes, surface mining, and deep excavation. The method of excavation depends on a number of different factors, such as the depth of the coal deposit below the ground, geological factors such as soil composition, topography, climate, available local resources, etc.

Surface mining is used to scrape off coal that is available on the surface, or just a few feet underground. This can even include mountains of coal deposit, which is extracted by using explosives and blowing up the mountains, later collecting the fragmented coal and process them.

Deep underground mining makes use of underground tunnels, which is built, or dug through, to reach the center of the coal deposit, from where the coal is dug out and brought to the surface by coal workers. This is perhaps the most dangerous excavation procedure, where the lives of all the miners are constantly at a risk.

Investing In Coal

Investing in coal is a safe bet. There are still large reserves of coal deposits around the world, and due to the popularity, coal will be continued to be used as fuel for manufacturing process. Every piece of investment you make in any sort of industry or a manufacturing process ultimately depends on the amount of output the industry can deliver, which is dependent on the usage of any form of fuel, and in most cases, coal.

One might argue that coal usage leads to pollution and lower standards of hygiene for coal workers. This was arguably true in former years; however, newer coal mining companies are taking steps to assure that the environmental aspects of coal mining and usage are kept minimized, all the while providing better working environment and benefits package for their workers. If you can find a mining company that promises all these, and the one that also works within the law, you can be assured safety for your investments in coal.

Source: http://ezinearticles.com/?The-Coal-Mining-Industry-And-Investing-In-It&id=5871879

How Extracting Job Postings Can Increase Revenue for Job Board Websites

For many people, job board websites present a great opportunity to bolster their search for their ideal job opening. They are the ideal avenue for prospective employers to meet right-fit employees. Employers post information about different openings in their companies, and job seekers respond to those posts with their profiles and resumes. This process gets carried out until the employer in question hits upon the right candidate for the job and the deal is closed.

For the job board website owner, revenue can come from many sources. Most job board websites charge membership fee from employers to put up their posts about vacant positions for the consideration of job seekers registered to the website. Revenue can also come from targeted advertising, premium services and profile upgrades for both hiring and seeking parties.

The most important wealth that any job board website can have is the sheer volume of job openings on display. With a large volume of openings, job board website owners not only get insight about market trends and opportunities, they can also lure both job seekers and employers to try out their services, thereby benefiting from their massive participation. This is one aspect where job board website owners can choose to crawl job websites to get targeted, relevant and organic information. Such informative and intelligent crawling can go on to bring about an overall increase in their revenue.

How Job Boards Work

Job boards work on a simple principle – providing a common platform where demand meets supply. Companies are always looking to hire the right people for their vacancies. Similarly bright professionals are always looking for a chance to get hired and go on to work with a reputed company. A job board website aims to be an interface between these two parties. They encourage job seekers to create accounts and profiles, while inviting prospective employers to make their own profiles and post their requirements in the form of job listings, much like posting classified advertisement in a newspaper. Interested candidates can then reply to these listings with their own information, resumes and cover letters to take the hiring process ahead.

To reach the optimal volume of job postings, seeker profiles and accurate information about all parties involved, one thing that can provide a giant boost to any job board website is scraping job websites. As the owner of a job board website, you can choose to scrape job listings for a wide number of practical and effective applications which can bring better revenue for your business.

How Does Scraping Work?

If you are looking to multiply your revenue, increase your reach and penetrate the already overcrowded job board market, you can choose to employ the services of a company that provides web scraping for job listings. Using the information you provide and the requirements that you specify, these professionals use a web scraper to crawl job listings across a large number of job board websites.

All the data that is received is stored for further examination and use. By using this technique, you can gather a wealth of important data on critical pointers, including detailed job seeker profiles, detailed employer profiles and accurate descriptions of actual, live job postings. This treasure trove of information can help you in a number of different ways.

For starters, you can be ensured that you always have a good volume of job postings in your job board website – a sure way to attract both job seekers and employers. You can also ensure that your job postings remain current and updated, and significantly cut down on your maintenance burden by employing this innovative and effective technique.

How Extracting Job Postings Can Help?

Extracting job listings from websites can be an immensely beneficial process for your job board website. It is a no-nonsense, hassle-free process that enables you to keep all your listings and all your job seeker profiles detailed, comprehensive and full of current and accurate information.

For a job board website, using data from publicly available websites for targeted use can give rise to some significant challenges –

•    Scale – You have to actively monitor thousands of relevant websites on a daily basis to ensure the integrity and reliability of the generated data.

•    Speed – You have to keep monitoring all your old resources over and over again to ensure that your listings remain current and any instance of an expired job listing gets flagged down so that you can remove it from your own job board website.

•    Breadth – You face the challenge of being able to regularly retrieve good quality content from websites which are difficult to access.

Recruitment Life Cycle

Using a highly customized, highly efficient and fully automated tool like a web scraper can help you overcome these challenges, and draw in significant revenues for your job board website. Handling such a vast and challenging task manually is not only counterintuitive, but it can also prove to be an extremely expensive undertaking in the long-term. Hiring professionals who can use automated tools for job scraping eliminates the drudgery and dreariness of this massive task. Additionally, it increases speed and efficiency, and makes it really easy for you to receive highly targeted and relevant information which is tailor made for your requirements. The data that you get from job site scraping is organic, actionable data which you can integrate in your business workflow and increase your revenue.

An efficient web scraper constantly scrapes job listings from a large number of high authority sources including job boards, online classified advertisements, Fortune 1000 websites, trade association websites and other sources. The fully automated process provides you with real-time information and feedback about changes and new additions to thousands of sources that feature job listings.

A highly customized web scraper can give a number of important advantages when it comes to scraping job boards. These advantages can help you with automating the process efficiently. This assists in cutting down on processed time duration and the proper streamlining of your web scraping endeavor –

•    You can monitor scores of important and relevant websites in real-time. You can also set up alerts the moment old job postings are taken down and new ones are posted.

•    You can customize web scraping tools to track particular data fields only for changes or updates. This way you can avoid repetitive reloading off old, already collected data.

•    You can also configure your web scraping tool to be agnostic towards changes in websites, thereby taking out a large chunk of possible maintenance time.

•    You can configure your web scraping tool to normalize and standardize data fields in resumes. This will make them ready for automated comparison and matching.

The Advantages

To compete in the highly competitive and saturated job board market, you need to go that extra mile with your own job board website. With the help of expert automated web scraping services, you can give your job board website the edge that it needs to survive and rise above the stiff competition.

You can continue to increase the scale of your operations and multiply your revenue. Using various means of web scraping you are able to provide authoritative, relevant and current information about job listings. When you successfully integrate automated web scraping into your workflow, it adds meaningful value on many levels -

Competitive Edge

You can surge ahead of the competition by offering your customers heightened speed and accuracy for all your job listings. Since you get real-time alerts when new job postings are added and old ones are removed, you can make information available to your customers within a short span of time. Thus, you can ensure that all content on your job board website stays current and updated.

Crawl Job boards

Quality Listings

You can bring in new business by offering a detailed and comprehensive list of job listings both in terms of quality and volume. Using a highly customized and sophisticated automated web scraping tool to gather your information works in your favor. It enables you to further simplify your access to specialized niches like classifieds sections of online newspapers, trade association websites and message boards.

Tremendous Value-add

You can provide more value to potential employers by maintaining a large database containing job seeker profiles. These are accurate right down to the very last detail. This can be achieved efficiently by scraping and storing full profiles at high speeds. You can then configure your scraper to record any changes or updates to individual profiles.

Targeted profiling

You can provide your customers with information that goes an extra mile and establishes a differentiating factor from your competitors. This can be achieved easily by fine tuning your web scraping efforts. Here, you need to enhance individual profiles by adding and supplementing them with further external information. This information can be pulled from public sources like social networks and on boarded with your existing profiles.

High degree of accuracy

You can achieve unmatched accuracy while matching applicant profiles to specific job listings. This can be achieved by normalizing important fields of applicant profiles and resumes to support fast, efficient automated comparisons, checks and matches.

Source: https://www.promptcloud.com/blog/how-scraping-job-postings-from-job-portals-helps-job-board-websites/