Lianja

A Simple Web Crawler

See more Spider Examples

This demonstrates a very simple web crawler using the Chilkat Spider component. Lianja

llSuccess = .F.

loSpider = createobject("CkSpider")

loSeenDomains = createobject("CkStringArray")
loSeedUrls = createobject("CkStringArray")

loSeenDomains.Unique = .T.
loSeedUrls.Unique = .T.

// You will need to change the start URL to something else...
loSeedUrls.Append("http://something.whateverYouWant.com/")

// Set outbound URL exclude patterns
// URLs matching any of these patterns will not be added to the 
// collection of outbound links.
loSpider.AddAvoidOutboundLinkPattern("*?id=*")
loSpider.AddAvoidOutboundLinkPattern("*.mypages.*")
loSpider.AddAvoidOutboundLinkPattern("*.personal.*")
loSpider.AddAvoidOutboundLinkPattern("*.comcast.*")
loSpider.AddAvoidOutboundLinkPattern("*.aol.*")
loSpider.AddAvoidOutboundLinkPattern("*~*")

// Use a cache so we don't have to re-fetch URLs previously fetched.
loSpider.CacheDir = "c:/spiderCache/"
loSpider.FetchFromCache = .T.
loSpider.UpdateCache = .T.

do while loSeedUrls.Count > 0

    lcUrl = loSeedUrls.Pop()
    loSpider.Initialize(lcUrl)

    // Spider 5 URLs of this domain.
    // but first, save the base domain in seenDomains
    lcDomain = loSpider.GetUrlDomain(lcUrl)
    loSeenDomains.Append(loSpider.GetBaseDomain(lcDomain))

    for i = 0 to 4
        llSuccess = loSpider.CrawlNext()
        if (llSuccess = .T.) then

            // Display the URL we just crawled.
            ? loSpider.LastUrl

            // If the last URL was retrieved from cache,
            // we won't wait.  Otherwise we'll wait 1 second
            // before fetching the next URL.
            if (loSpider.LastFromCache <> .T.) then
                loSpider.SleepMs(1000)
            endif

        else
            // cause the loop to exit..
            i = 999
        endif

    next

    // Add the outbound links to seedUrls, except
    // for the domains we've already seen.
    for i = 0 to loSpider.NumOutboundLinks - 1

        lcUrl = loSpider.GetOutboundLink(i)
        lcDomain = loSpider.GetUrlDomain(lcUrl)
        lcBaseDomain = loSpider.GetBaseDomain(lcDomain)
        if (loSeenDomains.Contains(lcBaseDomain) = .F.) then
            // Don't let our list of seedUrls grow too large.
            if (loSeedUrls.Count < 1000) then
                loSeedUrls.Append(lcUrl)
            endif

        endif

    next

enddo


release loSpider
release loSeenDomains
release loSeedUrls