data_store.js

const express = require('express') 
const fs = require('fs')

const DATA_DIR = 'aedb_data' ; 


const app = express() ;
 

app.use(express.json())

const hashtable = {}

app.post('/memory/:key' , (req , res ) => { 
    hashtable[req.params.key] = req.body.data ;
    console.log(req.body.data) ; 
    res.send() ;
});

app.get('/memory/:key' , (req, res ) => { 
    const key = req.params.key ; 
    if( key in hashtable ) {
        res.send(hashtable[key]) ;
        return ;
    }
    res.send('null') ; 
});


app.post('/disk/:key' , (req , res) => { 
    const destinationfile = `${DATA_DIR}/${req.params.key}`;
    fs.writeFileSync(destinationfile , req.body.data) ; 
    res.send(); 
});


app.get('/disk/:key' , (req , res ) => {
    const destinationfile = `${DATA_DIR}/${req.params.key}`;
    try{
        const data = fs.readFileSync(destinationfile);
        res.send(data);
    }
    catch(e){
        res.send('null');
    }
});


app.listen(3001 , ()=> {
     console.log(`Listening on the port 3001!`);
});