NodeJs Decode to readable text

Question

PROBLEM

I want to receive data from a device using IP Address via NodeJs. But I received the following data:

What I've Tried

This is the code that I've been able to get, which still produces the problem I described above.

var app = require('http').createServer(handler);
var url = require('url') ;
var statusCode = 200;

app.listen(6565);

function handler (req, res) {
 var data = '';

req.on('data', function(chunk) {
  data += chunk;
});

req.on('end', function() {
console.log(data.toString());
fs = require('fs');
fs.appendFile('helloworld.txt', data.toString(), function (err) {
  if (err) return console.log(err);
});
});

res.writeHead(statusCode, {'Content-Type': 'text/plain'});
res.end();
}

And below is the result I received for console.log(req.headers)

So my question is, how do I decode the data? and anyone know what type of data are they?

Your program is working just fine. The data being sent needs to be sorted out. Can you help us with an example data? — Aakash Verma, Jul 20 '17 at 04:41
do you mean example data sent from device? The manufacturer didn't gave it. Thank you for your prompt reply. — Amalina Aziz, Jul 20 '17 at 04:59
What does `console.log(res.headers)` show inside `handler()`? — mscdex, Jul 20 '17 at 05:46
Yes, I meant that, @AmalinaAziz. Do you know what kind of request object you are receiving? Please write the request object. — Aakash Verma, Jul 20 '17 at 06:03
Haha , this has been a problem for me and almost everyone. I was hoping that somehow I could send the request object as a whole as the response but was unable to do so. Read my exact problem [here](https://stackoverflow.com/questions/17251553/node-js-request-object-documentation) — Aakash Verma, Jul 20 '17 at 06:29
Might be useful: https://stackoverflow.com/questions/26672997/how-to-read-content-type-application-octet-stream-request-in-node-js — euvl, Jul 20 '17 at 08:46

Aakash Verma · Answer 1 · 2017-07-20T10:09:01.317

1

Use Buffers to handle octet streams.

function handler (req, res) {

    let body=[];

    req.on('data', function(chunk) {
        body.push(chunk);
    });


     req.on('end', function() {
        body = Buffer.concat(body).toString('utf8');
    ...

edited Jul 20 '17 at 10:09

answered Jul 20 '17 at 08:36

Aakash Verma

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Try this and let me know :/ – Aakash Verma Jul 20 '17 at 09:12
`chunk` is already a Buffer. Also, `Buffer.concat` requires an array of Buffer instances, not a single one, and should really be called in the `end` handler. – robertklep Jul 20 '17 at 09:12
@robertklep Thanks a lot! I have got so rusty. – Aakash Verma Jul 20 '17 at 09:15
Lastly: because the response is `application/octet-stream`, it's likely to be a binary format, so calling `toString()` on it may mangle it (however, it seems that OP doesn't know what the format of the data is, so it may be _anything_). – robertklep Jul 20 '17 at 09:17
@AmalinaAziz Why are you suggesting that edit? Did the previous one work for you? – Aakash Verma Jul 20 '17 at 09:19
@AakashVerma missing ). but the buffer one didn't work. – Amalina Aziz Jul 20 '17 at 09:21
@robertklep Isn't toString() actually specified by the Buffer class to do that? I agree that the encoding is optional. – Aakash Verma Jul 20 '17 at 09:21
@AakashVerma with `toString()`, you're telling Node to try and convert the binary data to a (UTF-8-encoded) string, but it may not be a string, or UTF-8-encoded, at all. – robertklep Jul 20 '17 at 09:22
@AmalinaAziz what exactly isn't working? We can't help you with decoding the data properly if you don't know what it actually is. – robertklep Jul 20 '17 at 09:23
@robertklep Okay but if we are able to get a string representation of it, we can later know what to do. Aziz doesn't know what data format or what data he is receiving. – Aakash Verma Jul 20 '17 at 09:59
@AakashVerma in that case, you want to use `toString('binary')`, so Node will not try to convert it to UTF-8. – robertklep Jul 20 '17 at 10:01

NodeJs Decode to readable text

1 Answers1