Spider C Reference Documentation

Spider

Chilkat Spider web crawler component.

Create/Dispose

HCkSpider CkSpider_Create(void);

Creates an instance of the HCkSpider object and returns a handle (i.e. a "void *" pointer). The handle is passed in the 1st argument for the functions listed on this page.

void CkSpider_Dispose(HCkSpider handle);

Objects created by calling CkSpider_Create must be freed by calling this method. A memory leak occurs if a handle is not disposed by calling this function. Also, any handle returned by a Chilkat "C" function must also be freed by the application by calling the appropriate Dispose method, such as CkSpider_Dispose.

Callback Functions

Callback Functions are Introduced in Chilkat v9.5.0.56

void CkSpider_setAbortCheck(HCkHttp cHandle, BOOL (*fnAbortCheck)());

Provides the opportunity for a method call to be aborted. If TRUE is returned, the operation in progress is aborted. Return FALSE to allow the current method call to continue. This callback function is called periodically based on the value of the HeartbeatMs property. (If HeartbeatMs is 0, then no callbacks are made.) As an example, to make 5 AbortCheck callbacks per second, set the HeartbeatMs property equal to 200.

C Example using Callback Functions

void CkSpider_setPercentDone(HCkHttp cHandle, BOOL (*fnPercentDone)(int pctDone));

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 callback is only called 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 methods 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).

This callback counts as an AbortCheck callback, and takes the place of the AbortCheck event when it fires.

The return value indicates whether the method call should be aborted, or whether it should proceed. Return TRUE to abort, and FALSE to proceed.

void CkSpider_setProgressInfo(HCkHttp cHandle, void (*fnProgressInfo)(const char *name, const char *value));

This is a general callback that provides name/value information about what is happening at certain points during a method call. To see the information provided in ProgressInfo callbacks, if any, write code to handle this event and log the name/value pairs. Most are self-explanatory.

void CkSpider_setTaskCompleted(HCkHttp cHandle, void (*fnTaskCompleted)(HCkTask hTask));

Called in the background thread when an asynchronous task completes. (Note: When an async method is running, all callbacks are in the background thread.)

Properties

BOOL CkSpider_getAbortCurrent(HCkSpider cHandle);

void CkSpider_putAbortCurrent(HCkSpider cHandle, BOOL newVal);

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.)

BOOL CkSpider_getAvoidHttps(HCkSpider cHandle);

void CkSpider_putAvoidHttps(HCkSpider cHandle, BOOL newVal);

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

void CkSpider_getCacheDir(HCkSpider cHandle, HCkString retval);

void CkSpider_putCacheDir(HCkSpider cHandle, const char *newVal);

const char *CkSpider_cacheDir(HCkSpider cHandle);

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

BOOL CkSpider_getChopAtQuery(HCkSpider cHandle);

void CkSpider_putChopAtQuery(HCkSpider cHandle, BOOL newVal);

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).

int CkSpider_getConnectTimeout(HCkSpider cHandle);

void CkSpider_putConnectTimeout(HCkSpider cHandle, int newVal);

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

void CkSpider_getDebugLogFilePath(HCkSpider cHandle, HCkString retval);

void CkSpider_putDebugLogFilePath(HCkSpider cHandle, const char *newVal);

const char *CkSpider_debugLogFilePath(HCkSpider cHandle);

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.

void CkSpider_getDomain(HCkSpider cHandle, HCkString retval);

const char *CkSpider_domain(HCkSpider cHandle);

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

BOOL CkSpider_getFetchFromCache(HCkSpider cHandle);

void CkSpider_putFetchFromCache(HCkSpider cHandle, BOOL newVal);

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

int CkSpider_getHeartbeatMs(HCkSpider cHandle);

void CkSpider_putHeartbeatMs(HCkSpider cHandle, int newVal);

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.

void CkSpider_getLastErrorHtml(HCkSpider cHandle, HCkString retval);

const char *CkSpider_lastErrorHtml(HCkSpider cHandle);

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.

void CkSpider_getLastErrorText(HCkSpider cHandle, HCkString retval);

const char *CkSpider_lastErrorText(HCkSpider cHandle);

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.

void CkSpider_getLastErrorXml(HCkSpider cHandle, HCkString retval);

const char *CkSpider_lastErrorXml(HCkSpider cHandle);

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.

BOOL CkSpider_getLastFromCache(HCkSpider cHandle);

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

void CkSpider_getLastHtml(HCkSpider cHandle, HCkString retval);

const char *CkSpider_lastHtml(HCkSpider cHandle);

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

void CkSpider_getLastHtmlDescription(HCkSpider cHandle, HCkString retval);

const char *CkSpider_lastHtmlDescription(HCkSpider cHandle);

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

Extract HTML Title, Description, Keywords

void CkSpider_getLastHtmlKeywords(HCkSpider cHandle, HCkString retval);

const char *CkSpider_lastHtmlKeywords(HCkSpider cHandle);

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

Extract HTML Title, Description, Keywords

void CkSpider_getLastHtmlTitle(HCkSpider cHandle, HCkString retval);

const char *CkSpider_lastHtmlTitle(HCkSpider cHandle);

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

Extract HTML Title, Description, Keywords

BOOL CkSpider_getLastMethodSuccess(HCkSpider cHandle);

void CkSpider_putLastMethodSuccess(HCkSpider cHandle, BOOL newVal);

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.

void CkSpider_getLastModDate(HCkSpider cHandle, SYSTEMTIME *retval);

This property is deprecated. It will be removed in a future version.

The last-modification date of the last URL spidered.

void CkSpider_getLastModDateStr(HCkSpider cHandle, HCkString retval);

const char *CkSpider_lastModDateStr(HCkSpider cHandle);

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

void CkSpider_getLastUrl(HCkSpider cHandle, HCkString retval);

const char *CkSpider_lastUrl(HCkSpider cHandle);

The URL of the last page spidered.

int CkSpider_getMaxResponseSize(HCkSpider cHandle);

void CkSpider_putMaxResponseSize(HCkSpider cHandle, int newVal);

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

int CkSpider_getMaxUrlLen(HCkSpider cHandle);

void CkSpider_putMaxUrlLen(HCkSpider cHandle, int newVal);

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

int CkSpider_getNumAvoidPatterns(HCkSpider cHandle);

The number of avoid patterns previously set by calling AddAvoidPattern.

int CkSpider_getNumFailed(HCkSpider cHandle);

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

int CkSpider_getNumOutboundLinks(HCkSpider cHandle);

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

int CkSpider_getNumSpidered(HCkSpider cHandle);

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

int CkSpider_getNumUnspidered(HCkSpider cHandle);

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

Getting Started Example

BOOL CkSpider_getPreferIpv6(HCkSpider cHandle);

void CkSpider_putPreferIpv6(HCkSpider cHandle, BOOL newVal);

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.

void CkSpider_getProxyDomain(HCkSpider cHandle, HCkString retval);

void CkSpider_putProxyDomain(HCkSpider cHandle, const char *newVal);

const char *CkSpider_proxyDomain(HCkSpider cHandle);

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

void CkSpider_getProxyLogin(HCkSpider cHandle, HCkString retval);

void CkSpider_putProxyLogin(HCkSpider cHandle, const char *newVal);

const char *CkSpider_proxyLogin(HCkSpider cHandle);

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

void CkSpider_getProxyPassword(HCkSpider cHandle, HCkString retval);

void CkSpider_putProxyPassword(HCkSpider cHandle, const char *newVal);

const char *CkSpider_proxyPassword(HCkSpider cHandle);

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

int CkSpider_getProxyPort(HCkSpider cHandle);

void CkSpider_putProxyPort(HCkSpider cHandle, int newVal);

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

int CkSpider_getReadTimeout(HCkSpider cHandle);

void CkSpider_putReadTimeout(HCkSpider cHandle, int newVal);

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

BOOL CkSpider_getUpdateCache(HCkSpider cHandle);

void CkSpider_putUpdateCache(HCkSpider cHandle, BOOL newVal);

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

void CkSpider_getUserAgent(HCkSpider cHandle, HCkString retval);

void CkSpider_putUserAgent(HCkSpider cHandle, const char *newVal);

const char *CkSpider_userAgent(HCkSpider cHandle);

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)"

BOOL CkSpider_getUtf8(HCkSpider cHandle);

void CkSpider_putUtf8(HCkSpider cHandle, BOOL newVal);

When set to TRUE, all "const char *" arguments are interpreted as utf-8 strings. If set to FALSE (the default), then "const char *" arguments are interpreted as ANSI strings. Also, when set to TRUE, and Chilkat method returning a "const char *" is returning the utf-8 representation. If set to FALSE, all "const char *" return values are ANSI strings.

BOOL CkSpider_getVerboseLogging(HCkSpider cHandle);

void CkSpider_putVerboseLogging(HCkSpider cHandle, BOOL newVal);

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.

void CkSpider_getVersion(HCkSpider cHandle, HCkString retval);

const char *CkSpider_version(HCkSpider cHandle);

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

int CkSpider_getWindDownCount(HCkSpider cHandle);

void CkSpider_putWindDownCount(HCkSpider cHandle, int newVal);

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

void CkSpider_AddAvoidOutboundLinkPattern(HCkSpider cHandle, const char *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

void CkSpider_AddAvoidPattern(HCkSpider cHandle, const char *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

void CkSpider_AddMustMatchPattern(HCkSpider cHandle, const char *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

void CkSpider_AddUnspidered(HCkSpider cHandle, const char *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

BOOL CkSpider_CanonicalizeUrl(HCkSpider cHandle, const char *url, HCkString outStr);

const char *CkSpider_canonicalizeUrl(HCkSpider cHandle, const char *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 TRUE for success, FALSE for failure.

Canonicalize a URL

void CkSpider_ClearFailedUrls(HCkSpider cHandle);

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

void CkSpider_ClearOutboundLinks(HCkSpider cHandle);

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

void CkSpider_ClearSpideredUrls(HCkSpider cHandle);

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

BOOL CkSpider_CrawlNext(HCkSpider cHandle);

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

HCkTask CkSpider_CrawlNextAsync(HCkSpider cHandle);

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

BOOL CkSpider_FetchRobotsText(HCkSpider cHandle, HCkString outStr);

const char *CkSpider_fetchRobotsText(HCkSpider cHandle);

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 TRUE for success, FALSE for failure.

Fetch robots.txt for a Site

HCkTask CkSpider_FetchRobotsTextAsync(HCkSpider cHandle);

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

BOOL CkSpider_GetAvoidPattern(HCkSpider cHandle, int index, HCkString outStr);

const char *CkSpider_getAvoidPattern(HCkSpider cHandle, int index);

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

Returns TRUE for success, FALSE for failure.

BOOL CkSpider_GetBaseDomain(HCkSpider cHandle, const char *domain, HCkString outStr);

const char *CkSpider_getBaseDomain(HCkSpider cHandle, const char *domain);

To be documented soon.

Returns TRUE for success, FALSE for failure.

Convert a Domain Name into a "domain base"

BOOL CkSpider_GetFailedUrl(HCkSpider cHandle, int index, HCkString outStr);

const char *CkSpider_getFailedUrl(HCkSpider cHandle, int index);

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

Returns TRUE for success, FALSE for failure.

BOOL CkSpider_GetOutboundLink(HCkSpider cHandle, int index, HCkString outStr);

const char *CkSpider_getOutboundLink(HCkSpider cHandle, int index);

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

Returns TRUE for success, FALSE for failure.

BOOL CkSpider_GetSpideredUrl(HCkSpider cHandle, int index, HCkString outStr);

const char *CkSpider_getSpideredUrl(HCkSpider cHandle, int index);

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

Returns TRUE for success, FALSE for failure.

BOOL CkSpider_GetUnspideredUrl(HCkSpider cHandle, int index, HCkString outStr);

const char *CkSpider_getUnspideredUrl(HCkSpider cHandle, int index);

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

Returns TRUE for success, FALSE for failure.

BOOL CkSpider_GetUrlDomain(HCkSpider cHandle, const char *url, HCkString outStr);

const char *CkSpider_getUrlDomain(HCkSpider cHandle, const char *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 TRUE for success, FALSE for failure.

void CkSpider_Initialize(HCkSpider cHandle, const char *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

BOOL CkSpider_RecrawlLast(HCkSpider cHandle);

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.

HCkTask CkSpider_RecrawlLastAsync(HCkSpider cHandle);

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

BOOL CkSpider_SaveLastError(HCkSpider cHandle, const char *path);

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

Returns TRUE for success, FALSE for failure.

void CkSpider_SkipUnspidered(HCkSpider cHandle, int index);

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

void CkSpider_SleepMs(HCkSpider cHandle, int numMilliseconds);

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