Spider Lianja Reference Documentation

Spider

Chilkat Spider web crawler component.

Object Creation

loObject = createobject("CkSpider")

Properties

AbortCurrent As Boolean

Introduced in version 9.5.0.58

When set to .T., 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 .F. when the next method is called. When the abort occurs, this property is reset to .F.. Both synchronous and asynchronous method calls can be aborted. (A synchronous method call could be aborted by setting this property from a separate thread.)

AvoidHttps As Boolean

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

CacheDir As Character

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

ChopAtQuery As Boolean

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).

ConnectTimeout As Numeric

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

DebugLogFilePath As Character

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.

Domain As Character (read-only)

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

FetchFromCache As Boolean

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

LastErrorHtml As Character (read-only)

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.

LastErrorText As Character (read-only)

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.

LastErrorXml As Character (read-only)

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.

LastFromCache As Boolean (read-only)

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

LastHtml As Character (read-only)

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

LastHtmlDescription As Character (read-only)

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

Extract HTML Title, Description, Keywords

LastHtmlKeywords As Character (read-only)

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

Extract HTML Title, Description, Keywords

LastHtmlTitle As Character (read-only)

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

Extract HTML Title, Description, Keywords

LastMethodSuccess As Boolean

Introduced in version 9.5.0.52

Indicate whether the last method call succeeded or failed. A value of .T. indicates success, a value of .F. 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 = .T. and failure = .F..
  • 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 .T.. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.

LastModDateStr As Character (read-only)

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

LastUrl As Character (read-only)

The URL of the last page spidered.

MaxResponseSize As Numeric

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

MaxUrlLen As Numeric

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

NumAvoidPatterns As Numeric (read-only)

The number of avoid patterns previously set by calling AddAvoidPattern.

NumFailed As Numeric (read-only)

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

NumOutboundLinks As Numeric (read-only)

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

NumSpidered As Numeric (read-only)

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

NumUnspidered As Numeric (read-only)

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

Getting Started Example

PreferIpv6 As Boolean

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

ProxyDomain As Character

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

ProxyLogin As Character

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

ProxyPassword As Character

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

ProxyPort As Numeric

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

ReadTimeout As Numeric

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

UpdateCache As Boolean

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

UserAgent As Character

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)"

VerboseLogging As Boolean

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

Version As Character (read-only)

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

WindDownCount As Numeric

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

AddAvoidOutboundLinkPattern(pattern As Character)

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

AddAvoidPattern(pattern As Character)

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

AddMustMatchPattern(pattern As Character)

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

AddUnspidered(url As Character)

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

CanonicalizeUrl(url As Character) As Character

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 .T. for success, .F. for failure.

Canonicalize a URL

ClearFailedUrls()

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

ClearOutboundLinks()

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

ClearSpideredUrls()

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

CrawlNext() As Boolean

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 .F.. Information about the URL crawled is available in the properties LastUrl, LastFromCache, and LastModDate.

Crawling the Web

Getting Started Example

CrawlNextAsync() As CkTask

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

How to Run an Asynchronous Task

FetchRobotsText() As Character

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 .T. for success, .F. for failure.

Fetch robots.txt for a Site

FetchRobotsTextAsync() As CkTask

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

How to Run an Asynchronous Task

GetAvoidPattern(index As Numeric) As Character

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

Returns .T. for success, .F. for failure.

GetBaseDomain(domain As Character) As Character

To be documented soon.

Returns .T. for success, .F. for failure.

Convert a Domain Name into a "domain base"

GetFailedUrl(index As Numeric) As Character

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

Returns .T. for success, .F. for failure.

GetOutboundLink(index As Numeric) As Character

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

Returns .T. for success, .F. for failure.

GetSpideredUrl(index As Numeric) As Character

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

Returns .T. for success, .F. for failure.

GetUnspideredUrl(index As Numeric) As Character

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

Returns .T. for success, .F. for failure.

GetUrlDomain(url As Character) As Character

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 .T. for success, .F. for failure.

Initialize(domain As Character)

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

RecrawlLast() As Boolean

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.

RecrawlLastAsync() As CkTask

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

How to Run an Asynchronous Task

SaveLastError(path As Character) As Boolean

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

Returns .T. for success, .F. for failure.

SkipUnspidered(index As Numeric)

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

SleepMs(numMilliseconds As Numeric)

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