Working with Telescope and Integrating Blink

This week, I have started to work with Telescope.

Telescope is an open source web server and client application for aggregating and presenting a timeline of Seneca’s open source blogs. Telescope makes it easy to see what’s happening with open source at Seneca right now.

This month and till the end of the semester, I will be working to fix bugs in Telescope or implement new features. This is really exciting to me because Telescope uses many technologies. By working in this project, I will be able to work with these technologies some of which I have never worked with before.

The Setup

As Telescope is using many technologies, I thought setting up the development environment would be a bit difficult. But it was not. The environment setup guideline clearly describes everything that is needed to be done. I followed the guide and everything was setup in very short time. Telescope uses Redis and Elasticsearch. I used Docker to use those. Once everything is setup, I started Redis and Elasticsearch using Docker and the backend server with npm start. Querying http://localhost:3000/posts returned information about the 10 latest posts in Telescope.

Using Blink to Check URLs in the Posts in Telescope

As part of lab 6, I was required to use Blink to check all URLs mentioned in the latest 10 blog posts in Telescope. There were many ways to do this. I decided to write a bash script which will fetch latest posts from Telescope and pipe the contents of the post to Blink.

#!/usr/bin/env bash

if ! command -v jq &> /dev/null
then
    echo "JQ is not installed."
    echo "Please install jq by sudo apt install jq."
    exit
fi

if [ ! -f ./Blink.jar ]; then
    echo "Could not find Blink. Download from https://github.com/badalsarkar/Blink"
    exit
fi

telescopeLatestPostApi=http://localhost:3000/posts
data=$(curl -s $telescopeLatestPostApi | jq '.[] | .id')
for i in $data;
do
    i="${i%\"}"
    i="${i#\"}"
    echo 
    echo ====================================================
    echo Checking $telescopeLatestPostApi/$i
    echo ====================================================
    echo 
    curl -s $telescopeLatestPostApi/$i | java -jar ./Blink.jar -i
done

I needed to implement a new feature in Blink, which allows Blink to accept input from standard input for processing. This was accomplished with very minimal changes. I added a new CLI option -i.

The following function is the handler function for -i option-

if(Cli.isSet(Cli.in)) {
  configureUrlPrinter();
  try(BufferedReader reader = new BufferedReader(new InputStreamReader(System.in))){
    while(true) {
      String text = null;
      if((text = reader.readLine())!= null) {
        Checker.check(Extractor.extractUrlFromText(text, Pattern.compile(pattern)), urlPrinter);
      }
      else {
        break;
      }
    }
  }
  System.exit(0);
}

It basically reads from standard input and use Extractor and Checker class to do the necessary processing. I have added a new class- Extractor but this is existing code. I want to refactor some of the things in Blink. The Extractor class will replace FileParser class.

That was it.

The End Result

Running the bash script produces the following output.