Spider C# Reference Documentation

Spider

Current Version: 9.5.0.73

Chilkat Spider web crawler component.

Object Creation

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

Properties

AbortCurrent
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.)

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AvoidHttps
public bool AvoidHttps {get; set; }

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

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CacheDir
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.

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ChopAtQuery
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).

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ConnectTimeout
public int ConnectTimeout {get; set; }

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

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DebugLogFilePath
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.

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Domain
public string Domain {get; }

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

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FetchFromCache
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.

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HeartbeatMs
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.

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LastErrorHtml
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.

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LastErrorText
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.

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LastErrorXml
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.

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LastFromCache
public bool LastFromCache {get; }

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

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LastHtml
public string LastHtml {get; }

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

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LastHtmlDescription
public string LastHtmlDescription {get; }

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

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LastHtmlKeywords
public string LastHtmlKeywords {get; }

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

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LastHtmlTitle
public string LastHtmlTitle {get; }

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

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LastMethodSuccess
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.

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LastModDateStr
public string LastModDateStr {get; }

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

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LastUrl
public string LastUrl {get; }

The URL of the last page spidered.

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MaxResponseSize
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.

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MaxUrlLen
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.

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NumAvoidPatterns
public int NumAvoidPatterns {get; }

The number of avoid patterns previously set by calling AddAvoidPattern.

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NumFailed
public int NumFailed {get; }

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

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NumOutboundLinks
public int NumOutboundLinks {get; }

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

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NumSpidered
public int NumSpidered {get; }

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

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NumUnspidered
public int NumUnspidered {get; }

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

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PreferIpv6
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.

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ProxyDomain
public string ProxyDomain {get; set; }

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

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ProxyLogin
public string ProxyLogin {get; set; }

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

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ProxyPassword
public string ProxyPassword {get; set; }

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

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ProxyPort
public int ProxyPort {get; set; }

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

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ReadTimeout
public int ReadTimeout {get; set; }

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

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UpdateCache
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.

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UserAgent
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)"

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VerboseLogging
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.

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Version
public string Version {get; }

Version of the component/library, such as "9.5.0.63"

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WindDownCount
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.

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Methods

AddAvoidOutboundLinkPattern
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.

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AddAvoidPattern
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.

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AddMustMatchPattern
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.

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AddUnspidered
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.

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CanonicalizeUrl
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

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ClearFailedUrls
public void ClearFailedUrls();

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

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ClearOutboundLinks
public void ClearOutboundLinks();

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

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ClearSpideredUrls
public void ClearSpideredUrls();

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

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CrawlNext
public bool CrawlNext();

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.

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CrawlNextAsync (C#) (Mono C#) (.NET Core C#) (PowerShell)
public Task CrawlNextAsync();

Creates an asynchronous task to call the CrawlNext method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.

Returns null on failure

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FetchRobotsText
public string FetchRobotsText();

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

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FetchRobotsTextAsync (C#) (Mono C#) (.NET Core C#) (PowerShell)
public Task FetchRobotsTextAsync();

Creates an asynchronous task to call the FetchRobotsText method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.

Returns null on failure

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GetAvoidPattern
public string GetAvoidPattern(int index);

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

Returns null on failure

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GetBaseDomain
public string GetBaseDomain(string domain);

To be documented soon.

Returns null on failure

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GetFailedUrl
public string GetFailedUrl(int index);

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

Returns null on failure

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GetOutboundLink
public string GetOutboundLink(int index);

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

Returns null on failure

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GetSpideredUrl
public string GetSpideredUrl(int index);

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

Returns null on failure

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GetUnspideredUrl
public string GetUnspideredUrl(int index);

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

Returns null on failure

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GetUrlDomain
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

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Initialize
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.

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RecrawlLast
public bool RecrawlLast();

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.

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RecrawlLastAsync (C#) (Mono C#) (.NET Core C#) (PowerShell)
public Task RecrawlLastAsync();

Creates an asynchronous task to call the RecrawlLast method with the arguments provided. (Async methods are available starting in Chilkat v9.5.0.52.)

Note: Async method event callbacks happen in the background thread. Accessing and updating UI elements existing in the main thread may require special considerations.

Returns null on failure

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SaveLastError
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.

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SkipUnspidered
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.

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SleepMs
public void SleepMs(int numMilliseconds);

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

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Events

AbortCheck
public event AbortCheckEventHandler OnAbortCheck;

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 .NET Event Implementation

Args are passed using Chilkat.AbortCheckEventArgs

Event callback implementation:

private void spider_OnAbortCheck(object sender, Chilkat.AbortCheckEventArgs args)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Spider spider = new Chilkat.Spider();
spider.OnAbortCheck += spider_OnAbortCheck;

Chilkat Mono/.NET Core Event Implementation

Event callback implementation:

private void ENTRY_NAMEEventHandler OnENTRY_NAME
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Spider spider = new Chilkat.Spider();
// ...
Chilkat.Spider.AbortCheck abortCheck = new Chilkat.Spider.AbortCheck(handleAbortCheck);
spider.setAbortCheckCb(abortCheck);
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PercentDone
public event PercentDoneEventHandler OnPercentDone;

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 .NET Event Implementation

Args are passed using Chilkat.PercentDoneEventArgs

Event callback implementation:

private void spider_OnPercentDone(object sender, Chilkat.PercentDoneEventArgs args)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Spider spider = new Chilkat.Spider();
spider.OnPercentDone += spider_OnPercentDone;

Chilkat Mono/.NET Core Event Implementation

Event callback implementation:

private void ENTRY_NAMEEventHandler OnENTRY_NAME
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Spider spider = new Chilkat.Spider();
// ...
Chilkat.Spider.PercentDone percentDone = new Chilkat.Spider.PercentDone(handlePercentDone);
spider.setPercentDoneCb(percentDone);
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ProgressInfo
public event ProgressInfoEventHandler OnProgressInfo;

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 .NET Event Implementation

Args are passed using Chilkat.ProgressInfoEventArgs

Event callback implementation:

private void spider_OnProgressInfo(object sender, Chilkat.ProgressInfoEventArgs args)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Spider spider = new Chilkat.Spider();
spider.OnProgressInfo += spider_OnProgressInfo;

Chilkat Mono/.NET Core Event Implementation

Event callback implementation:

private void ENTRY_NAMEEventHandler OnENTRY_NAME
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Spider spider = new Chilkat.Spider();
// ...
Chilkat.Spider.ProgressInfo progressInfo = new Chilkat.Spider.ProgressInfo(handleProgressInfo);
spider.setProgressInfoCb(progressInfo);
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TaskCompleted
public event TaskCompletedEventHandler OnTaskCompleted;

Called in the background thread when an asynchronous task completes.

More Information and Examples

Chilkat .NET Event Implementation

Args are passed using Chilkat.TaskCompletedEventArgs

Event callback implementation:

private void spider_OnTaskCompleted(object sender, Chilkat.TaskCompletedEventArgs args)
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Spider spider = new Chilkat.Spider();
spider.OnTaskCompleted += spider_OnTaskCompleted;

Chilkat Mono/.NET Core Event Implementation

Event callback implementation:

private void ENTRY_NAMEEventHandler OnENTRY_NAME
	{
	    // application code goes here.
	}

To add an event handler:

Chilkat.Spider spider = new Chilkat.Spider();
// ...
Chilkat.Spider.TaskIdCompleted taskIdCompleted = new Chilkat.Spider.TaskIdCompleted(handleTaskIdCompleted);
spider.setTaskIdCompletedCb(taskIdCompleted);
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