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Request Google's Page-rank Programmatically

, 15 Aug 2007
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This article shows how Google's hashing algorithm works and how you can use it to check the page-rank of your sites.

Screenshot - pagerank-cp.jpg

Introduction

Google's PageRank (PR) is a "link analysis algorithm measuring the relative importance" (PR @wikipedia). The importance of PR nowadays is a lot lower than one or two years ago. Nevertheless, PR is the only ranking value that is public to all audience, which means it's the only factor with some transparency. For those who don't know: a PR of 10 is the highest around (like for apple.com), and 0 the lowest - those sites who don't even have a PR of 0 are in a kind of sandbox (a special filter to punish the site) or not indexed by Google.

Please forgive me for being lazy during English lessons @ school as I'm trying my best Smile | :)

Background

Google tries to measure the relevance of a domain/site by counting the links pointing to the site/domain. This is influenced by the number of links that link to the linking site - in fact, this kind of procedure is an iterative process, which needs a lot of computing power.

Many webmasters believe their ranking depends on the PR of their site - this, today, is not true. PR never was the only factor for Google's ranking, but it was the most important factor. Right now, it's not. And many people believe that Google tries to get rid of the PageRank because link traders are measuring the value (in $) of a link by PR - which is just stupid.

If you're interested in buying links, go with the following factors:

  • Link popularity (how often is the site, you're willing to buy a link from, linked?)
  • Domain popularity (^ + by different domains)
  • IP-popularity (^ + on different IPs)
  • Has the domain an "authority status"?
  • Is the content of the domain relevant for your content?
  • Has this domain a good ranking for keywords you want to rank good at?
  • How many outgoing links does this site have?

Because PR is the one and only factor we can have a look at, it's pretty nice to check it. And it's even more nice if we can do that on more than one Google data center at the same time.

Requesting the PR

Well, the easy part is the PR get request: it's just a simple HTTP-Request, with a little problem in it. Here's the request for www.codeproject.com:

http://toolbarqueries.google.com/search?client=navclient-auto&hl=en&ch=6771535612&ie=UTF-8
    &oe=UTF-8&features=Rank&q=info:http%3A%2F%2Fwww.codeproject.com%2F

Well, this seems to be easy, but there's this little:

ch=6771535612

which is a hash value referencing the domain we want to get the PR for. This hashing algorithm was not developed by Google, it's the perfect hashing algorithm by Bob Jenkins.

After some folks ported the code to PHP, I tried to do a port to C# - and here we go.

But before that, I need to mention that (after I finished my coding) I found another port by Miroslav Stompar, which you can find here.

To be honest, his port is better, so I modified my version, and here comes the solution that's my favorite: .

Ported to C#

using System;
using System.Collections.Generic;
using System.Text;  
using System.Text.RegularExpressions;
using System.Net;
using System.IO;

namespace GooglePR
{
    class GetPR
    {
        private const UInt32 myConst = 0xE6359A60;
        private static void _Hashing(ref UInt32 a, ref UInt32 b, ref UInt32 c)
        {
            a -= b; a -= c; a ^= c >> 13;
            b -= c; b -= a; b ^= a << 8;
            c -= a; c -= b; c ^= b >> 13;
            a -= b; a -= c; a ^= c >> 12;
            b -= c; b -= a; b ^= a << 16;
            c -= a; c -= b; c ^= b >> 5;
            a -= b; a -= c; a ^= c >> 3;
            b -= c; b -= a; b ^= a << 10;
            c -= a; c -= b; c ^= b >> 15;
        }
        public static string PerfectHash(string theURL)
        {
            url = string.Format("info:{0}", theURL);

            int length = url.Length;
            
            UInt32 a, b;
            UInt32 c = myConst;

            int k = 0;
            int len = length;

            a = b = 0x9E3779B9;

            while (len >= 12)
            {
                a += (UInt32)(url[k + 0] + (url[k + 1] << 8) + 
                     (url[k + 2] << 16) + (url[k + 3] << 24));
                b += (UInt32)(url[k + 4] + (url[k + 5] << 8) + 
                     (url[k + 6] << 16) + (url[k + 7] << 24));
                c += (UInt32)(url[k + 8] + (url[k + 9] << 8) + 
                     (url[k + 10] << 16) + (url[k + 11] << 24));
                _Hashing(ref a, ref b, ref c);
                k += 12;
                len -= 12;
            }
            c += (UInt32)length;
            switch (len) 
            {
                case 11: 
                    c += (UInt32)(url[k + 10] << 24); 
                    goto case 10;
                case 10: 
                    c += (UInt32)(url[k + 9] << 16); 
                    goto case 9;
                case 9: 
                    c += (UInt32)(url[k + 8] << 8); 
                    goto case 8;
                case 8: 
                    b += (UInt32)(url[k + 7] << 24); 
                    goto case 7;
                case 7: 
                    b += (UInt32)(url[k + 6] << 16); 
                    goto case 6;
                case 6: 
                    b += (UInt32)(url[k + 5] << 8); 
                    goto case 5;
                case 5: 
                    b += (UInt32)(url[k + 4]); 
                    goto case 4;
                case 4: 
                    a += (UInt32)(url[k + 3] << 24); 
                    goto case 3;
                case 3: 
                    a += (UInt32)(url[k + 2] << 16); 
                    goto case 2;
                case 2: 
                    a += (UInt32)(url[k + 1] << 8); 
                    goto case 1;
                case 1: 
                    a += (UInt32)(url[k + 0]); 
                    break;
                default: 
                    break;
            }
            
            _Hashing(ref a, ref b, ref c);

            return string.Format("6{0}", c);
        }

        public static int MyPR(string myURL)
        {
            string strDomainHash = PerfectHash(myURL);
            string myRequestURL = string.Format("http://toolbarqueries.google.com/" + 
                   "search?client=navclient-auto&ch={0}&features=Rank&q=info:{1}", 
                   strDomainHash, myURL);

            try
            {
                HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(myRequestURL);
                string myResponse = new StreamReader(
                       myRequest.GetResponse().GetResponseStream()).ReadToEnd();
                if (myResponse.Length == 0)
                    return 0;
                else
                    return int.Parse(Regex.Match(myResponse, 
                           "Rank_1:[0-9]:([0-9]+)").Groups[1].Value);
            }
            catch (Exception)
            {
                return -1;
            }
        }

    }
}

So many thanks to Miroslav, who did the better job Smile | :)

Example: An ASP.NET Version

Here you can find the ASP.NET version of a PR-Checker - this one checks the PR of a domain/site of different IPs, which means different Google data centers. Because Google only updates the shown PR (Toolbar PR) about every 3 months, this tool is nice to check, if there's an update running - while the update runs, you'll get different PRs for the same page (in case the PR raises or falls) - interesting, isn't it?

To check more than one data center, I just created a loop and dynamically replace the:

toolbarqueries.google.com

part of the request with a Google IP - a list of IPs can be found via Google Smile | :)

If the tool shows "-1", the PR couldn't be retrieved, due to any reason.

History

  • 0.2 - Uploaded source code
  • I got to mention something first: if you're using the uploaded example, then you are using the code by miro stampar - for some reasons, my code is blown up with other things, and I'm still working on it. So don't worry about why the code differs from the code in this article.

  • 0.1 - Correction of a variable name (myURL to url) - thx to CP-user ploufs Smile | :)

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

hartertobak

Germany Germany
No Biography provided

Comments and Discussions

 
AnswerMaking this work in 2013 [modified] Pinmemberpravin4work3-Mar-13 7:09 
QuestionCode to get Page Rank based on certain keyword or search term Pinmemberharish kkumar12-May-12 0:57 
BugThis is failing when there are special characters in the url like & PinmemberPokemonCraft17-Jan-12 10:40 
BugPage Rank is not working PinmemberMohsan Hassan26-Nov-11 8:13 
GeneralGoogle limit Pinmemberdeepspacecoder16-May-11 6:17 
GeneralVery nice (5) PinmemberAron Weiler6-Mar-11 8:51 
GeneralThanks very much Pinmemberjimbo809824-Sep-10 2:23 
GeneralGoogle is disabling the IP's Pinmemberempee18-Feb-10 20:06 
GeneralRe: Google is disabling the IP's Pinmemberjimbo809824-Sep-10 2:24 
GeneralJava PinmemberKris Reid27-Jan-10 7:41 
GeneralRe: Java PinmemberVamsiKrishnaBandi9-Oct-10 20:32 
Generalhi nice work Pinmemberabu subh29-Mar-09 10:25 
QuestionWhat about keywords? Pinmembershaychen4-Mar-09 1:20 
Hi,
 
I've notice that some PR tools has the ability to get keyword along with the site url and calculate the PR. Do you know how they do it? Is there a code for that too?
 
See the following link with the keywords: http://www.googlerankings.com/
 
thanks,
Shay
AnswerRe: What about keywords? Pinmemberhartertobak4-Mar-09 1:49 
GeneralRe: What about keywords? Pinmembershaychen4-Mar-09 2:32 
GeneralRe: What about keywords? Pinmemberhartertobak4-Mar-09 4:28 
GeneralRe: What about keywords? Pinmembershaychen4-Mar-09 5:52 
General403 on Server 2003 Pinmemberjoehinder5-Jan-09 7:15 
GeneralGreat source Pinmemberjeffwow2-Jul-08 13:13 
GeneralCode don't work and error on it (int length = url.Length;) Pinmemberploufs16-Aug-07 13:58 
AnswerRe: Code don't work and error on it (int length = url.Length;) Pinmemberhartertobak16-Aug-07 19:19 
GeneralNice. But one problem PinmemberIrfan Faruki16-Aug-07 4:51 
GeneralRe: Nice. But one problem Pinmemberhartertobak16-Aug-07 9:27 
GeneralRe: Nice. But one problem PinmemberIrfan Faruki16-Aug-07 11:04 
GeneralRe: Nice. But one problem Pinmemberhartertobak16-Aug-07 19:16 
GeneralSuggestion PinmemberGlen Harvy16-Aug-07 3:16 
GeneralRe: Suggestion Pinmemberhartertobak16-Aug-07 3:31 
GeneralRe: Suggestion PinmemberGlen Harvy16-Aug-07 10:58 
GeneralRe: Suggestion Pinmemberhartertobak16-Aug-07 19:38 
GeneralNice work. PinmemberSecrets16-Aug-07 3:07 
GeneralRe: Nice work. Pinmemberhartertobak16-Aug-07 3:24 

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