Spider C# WinRT Reference Documentation

Spider

Chilkat Spider web crawler component.

Object Creation

Chilkat.Spider obj = new Chilkat.Spider();

Properties

public bool AbortCurrent {get; set; }

Introduced in version 9.5.0.58

When set to true, causes the currently running method to abort. Methods that always finish quickly (i.e.have no length file operations or network communications) are not affected. If no method is running, then this property is automatically reset to false when the next method is called. When the abort occurs, this property is reset to false. Both synchronous and asynchronous method calls can be aborted. (A synchronous method call could be aborted by setting this property from a separate thread.)

public bool AvoidHttps {get; set; }

If set the 1 (true) the spider will avoid all HTTPS URLs. The default is 0 (false).

public string CacheDir {get; set; }

Specifies a cache directory to use for spidering. If either of the FetchFromCache or UpdateCache properties are true, this is the location of the cache to be used. Note: the Internet Explorer, Netscape, and FireFox caches are completely separate from the Chilkat Spider cache directory. You should specify a new and empty directory.

Caching Web Pages to the Filesystem

public bool ChopAtQuery {get; set; }

If equal to 1 (true), then the query portion of all URLs are automatically removed when adding to the unspidered list. The default value is 0 (false).

public int ConnectTimeout {get; set; }

The maximum number of seconds to wait while connecting to an HTTP server.

public string DebugLogFilePath {get; set; }

If set to a file path, causes each Chilkat method or property call to automatically append it's LastErrorText to the specified log file. The information is appended such that if a hang or crash occurs, it is possible to see the context in which the problem occurred, as well as a history of all Chilkat calls up to the point of the problem. The VerboseLogging property can be set to provide more detailed information.

This property is typically used for debugging the rare cases where a Chilkat method call hangs or generates an exception that halts program execution (i.e. crashes). A hang or crash should generally never happen. The typical causes of a hang are:

  1. a timeout related property was set to 0 to explicitly indicate that an infinite timeout is desired,
  2. the hang is actually a hang within an event callback (i.e. it is a hang within the application code), or
  3. there is an internal problem (bug) in the Chilkat code that causes the hang.

public string Domain {get; }

The domain name that is being spidered. This is the domain previously set in the Initialize method.

public bool FetchFromCache {get; set; }

If equal to 1 (true) then pages are fetched from cache when possible. If 0, the cache is ignored. The default value is 1. Regardless, if no CacheDir is set then the cache is not used.

Caching Web Pages to the Filesystem

public int HeartbeatMs {get; set; }

The number of milliseconds between each AbortCheck event callback. The AbortCheck callback allows an application to abort any method call prior to completion. If HeartbeatMs is 0 (the default), no AbortCheck event callbacks will fire.

public string LastErrorHtml {get; }

Provides information in HTML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

public string LastErrorText {get; }

Provides information in plain-text format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

public string LastErrorXml {get; }

Provides information in XML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

public bool LastFromCache {get; }

Equal to 1 if the last page spidered was fetched from the cache. Otherwise equal to 0.

public string LastHtml {get; }

The HTML text of the last paged fetched by the spider.

public string LastHtmlDescription {get; }

The HTML META description from the last page fetched by the spider.

Extract HTML Title, Description, Keywords

public string LastHtmlKeywords {get; }

The HTML META keywords from the last page fetched by the spider.

Extract HTML Title, Description, Keywords

public string LastHtmlTitle {get; }

The HTML title from the last page fetched by the spider.

Extract HTML Title, Description, Keywords

public bool LastMethodSuccess {get; set; }

Introduced in version 9.5.0.52

Indicate whether the last method call succeeded or failed. A value of true indicates success, a value of false indicates failure. This property is automatically set for method calls. It is not modified by property accesses. The property is automatically set to indicate success for the following types of method calls:

  • Any method that returns a string.
  • Any method returning a Chilkat object, binary bytes, or a date/time.
  • Any method returning a standard boolean status value where success = true and failure = false.
  • Any method returning an integer where failure is defined by a return value less than zero.

Note: Methods that do not fit the above requirements will always set this property equal to true. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.

public string LastModDateStr {get; }

The last modification date/time from the last page fetched by the spider.

public string LastUrl {get; }

The URL of the last page spidered.

public int MaxResponseSize {get; set; }

The maximum HTTP response size allowed. The spider will automatically fail any pages larger than this size. The default value is 250,000 bytes.

Setting a Maximum Response Size

public int MaxUrlLen {get; set; }

The maximum URL length allowed. URLs longer than this are not added to the unspidered list. The default value is 200.

Setting a Maximum URL Length

public int NumAvoidPatterns {get; }

The number of avoid patterns previously set by calling AddAvoidPattern.

public int NumFailed {get; }

The number of URLs in the component's failed URL list.

public int NumOutboundLinks {get; }

The number of URLs in the component's outbound links URL list.

public int NumSpidered {get; }

The number of URLs in the component's already-spidered URL list.

public int NumUnspidered {get; }

The number of URLs in the component's unspidered URL list.

Getting Started Example

public bool PreferIpv6 {get; set; }

If true, then use IPv6 over IPv4 when both are supported for a particular domain. The default value of this property is false, which will choose IPv4 over IPv6.

public string ProxyDomain {get; set; }

The domain name of a proxy host if an HTTP proxy is used.

public string ProxyLogin {get; set; }

If an HTTP proxy is used and it requires authentication, this property specifies the HTTP proxy login.

public string ProxyPassword {get; set; }

If an HTTP proxy is used and it requires authentication, this property specifies the HTTP proxy password.

public int ProxyPort {get; set; }

The port number of a proxy server if an HTTP proxy is used.

public int ReadTimeout {get; set; }

The maximum number of seconds to wait when reading from an HTTP server.

public bool UpdateCache {get; set; }

If equal to 1 (true) then pages saved to the cache. If 0, the cache is ignored. The default value is 1. Regardless, if no CacheDir is set then the cache is not used.

Caching Web Pages to the Filesystem

public string UserAgent {get; set; }

The value of the HTTP user-agent header field to be sent with HTTP requests. The default value is "Chilkat/1.0.0 (+http://www.chilkatsoft.com/ChilkatHttpUA.asp)"

public bool VerboseLogging {get; set; }

If set to true, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is false. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

public string Version {get; }

Version of the component/library, such as "9.4.1.42"

public int WindDownCount {get; set; }

The "wind-down" phase begins when this number of URLs has been spidered. When in the wind-down phase, no new URLs are added to the unspidered list. The default value is 0 which means that there is NO wind-down phase.

Methods

public void AddAvoidOutboundLinkPattern(string pattern);

Adds a wildcarded pattern to prevent collecting matching outbound link URLs. For example, if "*google*" is added, then any outbound links containing the word "google" will be ignored. The "*" character matches zero or more of any character.

Avoiding Outbound Links Matching Patterns

public void AddAvoidPattern(string pattern);

Adds a wildcarded pattern to prevent spidering matching URLs. For example, if "*register*" is added, then any url containing the word "register" is not spidered. The "*" character matches zero or more of any character.

Avoid URLs Matching Any of a Set of Patterns

public void AddMustMatchPattern(string pattern);

Adds a wildcarded pattern to limit spidering to only URLs that match the pattern. For example, if "*/products/*" is added, then only URLs containing "/products/" are spidered. This is helpful for only spidering a portion of a website. The "*" character matches zero or more of any character.

Must-Match Patterns

public void AddUnspidered(string url);

To begin spidering you must call this method one or more times to provide starting points. It adds a single URL to the component's internal queue of URLs to be spidered.

Crawling the Web

public string CanonicalizeUrl(string url);

Canonicalizes a URL by doing the following:

  • Drops username/password if present.
  • Drops fragment if present.
  • Converts domain to lowercase.
  • Removes port 80 or 443
  • Remove default.asp, index.html, index.htm, default.html, index.htm, default.htm, index.php, index.asp, default.php, .cfm, .aspx, ,php3, .pl, .cgi, .txt, .shtml, .phtml
  • Remove www. from the domain if present.

Returns null on failure

Canonicalize a URL

public void ClearFailedUrls();

Clears the component's internal list of URLs that could not be downloaded.

public void ClearOutboundLinks();

Clears the component's internal list of outbound URLs that will automatically accumulate while spidering.

public void ClearSpideredUrls();

Clears the component's internal list of already-spidered URLs that will automatically accumulate while spidering.

(awaitable) public IAsyncOperation<bool> CrawlNextAsync();

Crawls the next URL in the internal list of unspidered URLs. The URL is moved from the unspidered list to the spidered list. Any new links within the same domain and not yet spidered are added to the unspidered list. (providing that they do not match "avoid" patterns, etc.) Any new outbound links are added to the outbound URL list. If successful, the HTML of the downloaded page is available in the LastHtml property. If there are no more URLs left unspidered, the method returns false. Information about the URL crawled is available in the properties LastUrl, LastFromCache, and LastModDate.

Crawling the Web

Getting Started Example

(awaitable) public IAsyncOperation<string> FetchRobotsTextAsync();

Returns the contents of the robots.txt file from the domain being crawled. This spider component will not crawl URLs excluded by robots.txt. If you believe the spider is not behaving correctly, please notify us at support@chilkatsoft.com and provide information detailing a case that allows us to reproduce the problem.

Returns null on failure

Fetch robots.txt for a Site

public string GetAvoidPattern(int index);

Returns the Nth avoid pattern previously added by calling AddAvoidPattern. Indexing begins at 0.

Returns null on failure

public string GetBaseDomain(string domain);

To be documented soon.

Returns null on failure

Convert a Domain Name into a "domain base"

public string GetFailedUrl(int index);

Returns the Nth URL in the failed URL list. Indexing begins at 0.

Returns null on failure

public string GetOutboundLink(int index);

Returns the Nth URL in the outbound link URL list. Indexing begins at 0.

Returns null on failure

public string GetSpideredUrl(int index);

Returns the Nth URL in the already-spidered URL list. Indexing begins at 0.

Returns null on failure

public string GetUnspideredUrl(int index);

Returns the Nth URL in the unspidered URL list. Indexing begins at 0.

Returns null on failure

public string GetUrlDomain(string url);

Returns the domain name part of a URL. For example, if the URL is "http://www.chilkatsoft.com/test.asp", then "www.chilkatsoft.com" is returned.

Returns null on failure

public void Initialize(string domain);

Initializes the component to begin spidering a domain. Calling Initialize clears any patterns added via the AddAvoidOutboundLinkPattern, AddAvoidPattern, and AddMustMatchPattern methods. The domain name passed to this method is what is returned by the Domain property. The spider only crawls URLs within the same domain.

Crawling the Web

Getting Started Example

(awaitable) public IAsyncOperation<bool> RecrawlLastAsync();

Re-crawls the last URL spidered. This helpful when cookies set in a previous page load cause the page to be loaded differently the next time.

public bool SaveLastError(string path);

Saves the last-error information (the contents of LastErrorXml) to an XML formatted file.

Returns true for success, false for failure.

public void SkipUnspidered(int index);

Moves a URL from the unspidered list to the spidered list. This allows an application to skip a specific URL.

public void SleepMs(int numMilliseconds);

Suspends the execution of the current thread until the time-out interval elapses.

Events

Callbacks from asynchronous methods occur in a background thread. However, controls on the UI thread may only be accessed from the UI thread.Therefore, UI updates must be dispatched to the UI thread. One way to do this is as follows:

    public sealed partial class MainPage : Page
    {
        private Windows.UI.Core.CoreDispatcher m_dispatcher = null;

        public MainPage()
        {
            this.InitializeComponent();
            m_dispatcher = Windows.UI.Core.CoreWindow.GetForCurrentThread().Dispatcher;
        }


        async private void Http_ProgressInfo(object sender, Chilkat.ProgressInfoEventArgs eventArgs)
        {
            await m_dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
            {
                // Application code to update the UI goes here...
            });
        }

    }

public event AbortCheckEventHandler AbortCheck;

Provides the opportunity for a method call to be aborted. The AbortCheck event is fired periodically based on the value of the HeartbeatMs property. If HeartbeatMs is 0, then no AbortCheck events will fire. As an example, to fire 5 AbortCheck events per second, set the HeartbeatMs property equal to 200.

Chilkat WinRT C# Event Implementation

Args are passed using Chilkat.AbortCheckEventArgs

Event callback implementation:

private void spider_AbortCheck(object sender, Chilkat.AbortCheckEventArgs args)
	{
            await m_dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
            {
	        // The event callback is not in the main UI thread.  To safely update UI elements, encapsulate
                // application code in this way.
            });
	}

To add an event handler:

Chilkat.Spider spider = new Chilkat.Spider();
spider.AbortCheck += spider_AbortCheck;

public event BinaryDataEventHandler BinaryData;

Binary data provided by certain methods.

Chilkat WinRT C# Event Implementation

Args are passed using Chilkat.BinaryDataEventArgs

Event callback implementation:

private void spider_BinaryData(object sender, Chilkat.BinaryDataEventArgs args)
	{
            await m_dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
            {
	        // The event callback is not in the main UI thread.  To safely update UI elements, encapsulate
                // application code in this way.
            });
	}

To add an event handler:

Chilkat.Spider spider = new Chilkat.Spider();
spider.BinaryData += spider_BinaryData;

public event PercentDoneEventHandler PercentDone;

Provides the percentage completed for any method that involves network communications or time-consuming processing (assuming it is a method where a percentage completion can be measured). This event is only fired when it is possible to know a percentage completion, and when it makes sense to express the operation as a percentage completed. The pctDone argument will have a value from 1 to 100. For operations (Chilkat method calls) that complete very quickly, the number of PercentDone callbacks will vary, but the final callback should have a value of 100. For long running operations, no more than one callback per percentage point will occur (for example: 1, 2, 3, ... 98, 99, 100).

The PercentDone callback counts as an AbortCheck event. For method calls that complete quickly such that PercentDone events fire, it may be that AbortCheck events don't fire because the opportunity to abort is already provided in the PercentDone callback. For time consuming operations, where the amount of time between PercentDone callbacks are long, AbortCheck callbacks may be used to allow for the operation to be aborted in a more responsive manner.

The abort output argument provides a means for aborting the operation. Setting it to true will cause the method to abort and return a failed status (or whatever return value indicates failure).

Chilkat WinRT C# Event Implementation

Args are passed using Chilkat.PercentDoneEventArgs

Event callback implementation:

private void spider_PercentDone(object sender, Chilkat.PercentDoneEventArgs args)
	{
            await m_dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
            {
	        // The event callback is not in the main UI thread.  To safely update UI elements, encapsulate
                // application code in this way.
            });
	}

To add an event handler:

Chilkat.Spider spider = new Chilkat.Spider();
spider.PercentDone += spider_PercentDone;

public event ProgressInfoEventHandler ProgressInfo;

A general name/value event that provides information about what is happening during a method call. To find out what information is available, write code to handle this event and log the name/value pairs. Most are self-explanatory.

Chilkat WinRT C# Event Implementation

Args are passed using Chilkat.ProgressInfoEventArgs

Event callback implementation:

private void spider_ProgressInfo(object sender, Chilkat.ProgressInfoEventArgs args)
	{
            await m_dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
            {
	        // The event callback is not in the main UI thread.  To safely update UI elements, encapsulate
                // application code in this way.
            });
	}

To add an event handler:

Chilkat.Spider spider = new Chilkat.Spider();
spider.ProgressInfo += spider_ProgressInfo;

public event TaskCompletedEventHandler TaskCompleted;

Called in the background thread when an asynchronous task completes.

Chilkat WinRT C# Event Implementation

Args are passed using Chilkat.TaskCompletedEventArgs

Event callback implementation:

private void spider_TaskCompleted(object sender, Chilkat.TaskCompletedEventArgs args)
	{
            await m_dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
            {
	        // The event callback is not in the main UI thread.  To safely update UI elements, encapsulate
                // application code in this way.
            });
	}

To add an event handler:

Chilkat.Spider spider = new Chilkat.Spider();
spider.TaskCompleted += spider_TaskCompleted;

public event TextDataEventHandler TextData;

Text data provided by certain methods.

Chilkat WinRT C# Event Implementation

Args are passed using Chilkat.TextDataEventArgs

Event callback implementation:

private void spider_TextData(object sender, Chilkat.TextDataEventArgs args)
	{
            await m_dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
            {
	        // The event callback is not in the main UI thread.  To safely update UI elements, encapsulate
                // application code in this way.
            });
	}

To add an event handler:

Chilkat.Spider spider = new Chilkat.Spider();
spider.TextData += spider_TextData;