Basic Java: Intro to web search course

Elastic search Assignment

Assignment 1: indexing for web search

Your task is to apply your IR skills to build a processing pipeline that turns a Web site into structured knowledge. Your system should take HTML pages as input, process them using the kind of techniques that we have been looking at in the module, and output an index of terms identified in the documents.

This assignment comes in stages. Marks are given for each stage. You may choose not to attempt some stages. You might also implement a system that does not strictly follow the stages but will work in the same way. The stages are as follows:

Input/Output (10%) The system must be able to read Web pages (a small number will do here and they can be stored locally) and produce appropriately formatted output. The Web pages should be processed one at a time using the steps outlined below.

HTML Parsing (10%) Before the text can be analyzed it is necessary to get rid of the HTML tags. The result will be plain text. Note that if you simply delete all HTML tags, you will lose information such as meta tag keywords. Therefore, I strongly suggest that you use some tool to perform this task.

Pre-processing: Sentence Splitting, Tokenization and Normalization (10%) The next step should be to transform the input text into a normal form of your choice.

Part-of-Speech Tagging (10%) The input should be tagged with a suitable part-of-speech tagger, so that the result can then be processed in the next steps.

Selecting Keywords (20%) One aim of your system is to identify the words or phrases in the text that are most useful for indexing purposes. Your system should remove words which are not useful, such as very frequent words or stopwords. You should develop a selection method, possibly using POS tags (e.g. nouns and noun phrases) in combination with statistical/frequency information (e.g. using term frequency).

Stemming or Morphological Analysis (10%) Writing word stems to the database rather than words allows to treat various inflected forms of a word in the same way, i.e. bus and busses refer to exactly the same thing even though they are di erent words.

Engineering a Complete System (10%) The nal system should have control over all the individual components so that there is a single call and all the above steps will be performed.

You will have noticed that the percentages above only add up to 80%. This is because one of the important aspects of the project is that your work should be well documented and your code well commented. 20% of your mark will come from this. You should submit:

A description of your implementation: what the code does, and the software you used

Unedited and commented output from a run of the code submitted using these web pages:

(feel free to submit other runs as well, i.e. using Web pages of your own choice)

A short discussion of your solution focussing on functionality implemented and possible improvements and extensions.

You can implement your system either on the Linux or the Windows machines. Perl, Java, Python, C/C++, and shell scripts are good choices for this project, but you are by no means restricted to those languages. Identify suitable open-source tools that help you building your pipeline.