/lgu-crawler

LGU timetable Crawler

Primary LanguageTypeScript

LGU Crawler

A Blazingly fast crawler that scraps all data from the LGU timetable website.

✨ What is Special about this project?

  • Blazingly fast 🔥

    It is capable of retrieving all data in less than 30 sec, thanks to the Node Js Cluster module which allows parallel data fetching by spawning child process(same as OS fork).

  • Zero DB Dependencies 🧠

    Rather than relying on a database, this crawler stores scraped data in local files. These files subsequently serve as an API endpoint (utilizing Github Raw Content) for the frontend application

  • Zero Compromise on Security 🔐

    By storing data in local files, there arises a concern regarding privacy, as anyone can access the data by simply opening a GitHub repository. To address this issue we're using the Node Js crypto module. The data stored in the file will be encrypted which is later decrypted by the front-end application using private_key and iv.

  • Intuivtive Code & APIS 🦄

    This project uses both OOP and functional programming paradigms. for use cases, it exposes event-driven APIS which makes it easier for the the developer to build new applications on top of this project.

API Usage

Developers can use scrapped data on their websites using Github raw APIS. Even though data is public and can be accessed easily using HTTP requests but decryption is required to turn data into human readable.

This is how data encryption works and how you should approach it.

  • Plan Text: In the db folder every file name is encrypted with a sha-256 hash except a few. these files are useful for loading initial data like meta_data.json which contains all drop-down data.

  • File data decryption: Every file in the DB contains crypted text and some metadata which is helpful to know about which encoding and algorithm is being used. To decrypt files key (check symmetric key algorithm)and iv is also required. These credentials can be obtained by contacting the maintainer in the issue or discussion section.

  • File names: All file names are hashed by the sha-256 algorithm. To generate hash from user input the input must be arranged in the following order ${semester} ${program} ${section}`.replaceAll("/", "") before passing to hash function.

Diagram:

GET -> meta_data.json
|
| --> Generate hash from user input ('<semester> <program> <section>'.replaceAll('/', ''))
|
| --> GET base_url/generated_hash.json => timetable

Usage

  • Download Source Code

    git clone <this_repo>

    OR

    Download

  • Prepare Environment Variables

    • create .env file in the root of the project.

        # recommended if running locally
  NODE_ENV="development"

  # Note! default keys will work replace with your own keys if needed.

  # Must be 32   characters
  OPEN_DB_KEY="ae3ca465683436cbfd33e2ddd4aa0fcf9fbfcfe26d29379e111a01462f87ebeb"

  # Must be 16 characters
  OPEN_DB_IV="0bf4254a8293e5aedcdfcb8095c08ffa"

  # get session id from LGU timetable website
  PHPSESSID=""

    • paste following code in .env with your values.

    Appendix:

  • Run

      npx yarn
  npx yarn dev