Suite of tools for detecting changes in web pages and their rendering
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Overview of projects

  • JKernelMachines: a java library for learning with kernels. It is primary designed to deal with custom kernels that are not easily found in standard libraries, such as kernels on structured data. This library is developed by David Picard and new versions can be found here:

  • JDescriptors: a java library for deffirent color descriptors like SIFT and HSV. This library is developed at LIP6.

  • MarcAlizer: a supervised framework. It extracts features to create vectors for training/comparison and calculates the score based on similarities between vectors. It uses JKernelMachines and JDescriptors.

  • Pagelyzer: Main project that takes the screenshots, does the web segmentation and uses MarcAlizer to return the result.

Installing Dependencies

$ sudo apt-get install openjdk-7-jdk
$ sudo apt-get install xvfb (optional)

Using Pagelyzer will popup a window to render the web pages (to get a screenshot and also to do the segmentation). You can use Xvfb to make it headless. Xvfb is used incase if the Graphical User Interface (GUI) is not available in your system but also not the open pop-up window. You should first describe a display and then execute the jars on this display:

$ Xvfb:1 -screen 0 1024x768x24 &
$ DISPLAY=:1 java -jar ....

This ReadMe will explain the usage of different jar files obtained from this code source: Different executable jars generated from source code can be downloaded from

Command-line Parameters

Example_configFiles contains different configuration examples and its ReadMe explains each tag. SettingsFiles folder is a "must" folder. After downloading it, you can change its name but you should not change its subfolders names. js and ext folder should be always in the same folder. Then you update the subdir tag in the config file.


If you want to define "what is similar" and "what is dissimilar" according to your needs, you can first train the system:

| parameter | description | | ------------ | :----------------------------------------: | ------------------------------------------------------------- |
| config.xml | This is the path to the configuration file. Different examples can be found here: | annotations.txt | The path to a file that contains the annotated dataset to train the system.This is the file where you describe which pair of urls are simmilar/dissimilar. The file should have the following structure: URL1 \t URL2 \t ANNOTATION (0 dissimilar 1 similar).

$ java -cp Pagelyzer-libs.jar:PagelyzerTrain.jar  pagelyzer.Train config.xml   annotations.txt
$ java -jar java  -jar ./target/PagelyzerTrain-0.0.1-SNAPSHOT-jar-with-dependencies.jar config.xml   annotations.txt

This generates an output file and save it based on the settings on configuration file by "subdir" tag (config.xml). This file contains the information related to decision boundary and SVM and is used for comparison.


We can compare the web pages as follows:

parameter arguments description
url1 URI First URL
url2 URI Second URL
config path path to the configuration file (config.xml)
$ java -jar Pagelyzer-0.0.1-SNAPSHOT-jar-with-dependencies.jar -url1 -url2  -config  config.xml
$ java -cp Pagelyzer-libs.jar:Pagelyzer.jar  pagelyzer.JPagelyzer -url1 -url2  -config config.xml

This will give a score between -1 and 1. All the scores negatives mean that the pages are dissimilar and all scores positive mean that the pages are similar. The values are also ranked which means that two pages with a score 0.9 is more similar than two pages with a score 0.2. However, the score 0 means that the system is not able to decide if the pages are similar or not. It means that the training dataset is small or do not contain the diverse examples. The suggestion in that case is to train the system again with a bigger dataset.


This section will show you how to make tests with a bunch of url pairs at the same time.

| parameter | description | | ------------ | :----------------------------------------: | ------------------------------------------------------------- |
| test.txt | The path to a file that contains a list of urls that you would like to test URL1 \t URL2 | config.xml | The path to the configuration file (config.xml) | result.txt | The path to the file where you would like to save the results URL1 \t URL2 \t Score

$java  -cp Pagelyzer-libs.jar:Pagelyzer-0.0.1-SNAPSHOT-tests.jar Test test.txt  config.xml results.txt

Configuration file Details

Tag Description Possible Values
config:pagelyzer:run:default:parameter:get String value that tells the sytem what to do score: to return score; screenshot: just to get screenshots segmentation: just to do segmentation source: to save html code
config:pagelyzer:run:default:parameter:browser default browser firefox; chrome; opera;
config:pagelyzer:run:default:parameter:browser1 Browser for the first URL firefox; chrome; opera;
config:pagelyzer:run:default:parameter:browser2 Browser for the second URL firefox; chrome; opera;
config:pagelyzer:run:default:parameter:outputfile Path to save output for screenshot/source/segmentation --
config:pagelyzer:run:default:comparison:mode Describes the comparison mode content; hybrid; image;
config:pagelyzer:run:default:comparison:subdir Path to ext folder in the SettingsFiles --
config:pagelyzer:run:internal:server:remote:url URL of the remote web server where are located the javascripts injected by selenium --
config:pagelyzer:run:internal:server:local:ip IP address used by pagelyzer to its internal local web server --
config:pagelyzer:run:internal:server:local:port Port number used by pagelyzer to its internal local web server Default: 8016
config:pagelyzer:run:internal:server:local:wwwroot Path used by pagelyzer to its internal local web server Default: Current dir
config:pagelyzer:run:debug:screenshots:active Activate debuging mode Boolean
config:pagelyzer:run:debug:screenshots:path Path to store debugging files --
config:pagelyzer:run:debug:screenshots:filepattern How file should be named page#{n}.png becomes page1.png for url1, page2.png for url2
config:selenium:run:mode Use Webdriver class (local) or use remote instance (remote) local, remote
config:selenium:server:url URL for the remote instance --
config:bom:granularity Size of blocks for the web page segmentation 0-10
config:bom:separation Threshold for separation of blocks for the web page segmentation length in pixels