How can I return datas to Http Request?

[espruino-discuss]

Posted at 2020-03-24 by user109783

Now I use a SIM7600CE for 4G connection. The modules didn't adapt for this kind of sim card.
So I have to write my own module for it.

Now I can get response datas in this Method:

recv: function (sckt, maxLen) {
    if (sockData[sckt]) {
      var r;
      console.log("recv", sockData[sckt].length);
      if (sockData[sckt].length > maxLen) {
        r = sockData[sckt].substr(0, maxLen);
        sockData[sckt] = sockData[sckt].substr(maxLen);
        console.log("recv", sockData[sckt]);
      } else {
        r = sockData[sckt];
        sockData[sckt] = "";
        console.log("recv | socks[sckt]", socks[sckt]);
        if (socks[sckt] == "DataClose") {
          dbg("Got DataClose - forcing close");
          socks[sckt] = "closing";
        }
      }
      console.log("[recv data]", r)
      return r;
    }
    if (socks[sckt] == "closing" || !socks[sckt]) return -1; // close it
    return "";
  },

I think this part is the place where return datas to http.get().
But I can't recieve any datas in this place.
Do you have any introductions about how the datas flow in the network?

http.get("http://www.pur3.co.uk/hello.txt", function (res) {
      let str = ''; 
      res.on('data', chunk => {
        console.log("chunk",chunk);
        str += chunk;
      });
      res.on('end', () => {
        console.log("result: --->   ", str);
      });
    });

[espruino-discuss]

Posted at 2020-03-24 by Robin

Tue 2020.03.24

Has an attempt to place a console.log() statement just after the http.get request at L1a to see if anything is being detected/returned within the callback?
or use of the debugger?

Related content with fix

forum: http.request not working on Espruino Wifi

Could it be related to https

https://www.espruino.com/Internet#https

http://www.espruino.com/Internet

---

Posted at 2020-03-24 by user109783

The code

console.log("back from network?",res)
didn't print anything.

tp.get("http://www.pur3.co.uk/hello.txt", function (res) {
     console.log("back from network?",res)
      let str = ''; 
      res.on('data', chunk => {
        console.log("chunk",chunk);
        str += chunk;
      });
      res.on('end', () => {
        console.log("result: --->   ", str);
      });
    });

In the Mehtod recv(), I did got datas and retruned them. But where these datas go I really don't know, and how do they go back to http.get response body?

console.log("[recv data]", r)
return r;

---

Posted at 2020-03-24 by Robin

This might have the solution and a reasonable explanation:

'On the Internet page there is a simple example of sending data in the URL from a webpage, but it can be unreliable if anywhere between your browser and the Espruino decides to cache the received data.'

http://www.espruino.com/Posting+Forms

My suggestion is to post the response data *in it's entirety* so that others may take a look and compare to what should be in the response packet.
> 'how do they go back to'

Don't know but, could it be the use of the arrow functions not allowing binding to the http response object?

---

Posted at 2020-03-25 by user109783

This is the request message

GET /hello.txt HTTP/1.1
User-Agent: Espruino 2v04.401
Connection: close
Host: www.pur3.co.uk

And this is the response message

RECV FROM:93.93.135.13:80
+IPD259
HTTP/1.1 200 OK
Date: Wed, 25 Mar 2020 02:30:54 GMT
Server: Apache/2.4.18 (Ubuntu)
Last-Modified: Fri, 15 Nov 2013 15:42:26 GMT
ETag: "d-4eb390b887c80"
Accept-Ranges: bytes
Content-Length: 13
Connection: close
Content-Type: text/plain
Hello World!
+IPCLOSE: 0,1

I tried to put debuggers in two places. In this place, I can't reach the debugger 2.

     debugger;  // 1
    http.get("http://www.pur3.co.uk/hello.txt", function(res) {
      debugger;  //2
      let str = ''; 
      res.on('data', chunk => {
        console.log("chunk",chunk);
        str += chunk;
      });
      res.on('end', () => {
        console.log("Get some test request contents: --->   ", str);
      });
    });

And the second place here:

recv: function (sckt, maxLen) {
    if (sockData[sckt]) {
      console.log("ddddddddddddddd",sockData[sckt])
      var r;
      console.log("recv", sockData[sckt].length);
      if (sockData[sckt].length > maxLen) {
        r = sockData[sckt].substr(0, maxLen);
        sockData[sckt] = sockData[sckt].substr(maxLen);
        console.log("recv", sockData[sckt]);
      } else {
        r = sockData[sckt];
        sockData[sckt] = "";
        console.log("recv | socks[sckt]", socks[sckt]);
        if (socks[sckt] == "DataClose") {
          dbg("Got DataClose - forcing close");
          socks[sckt] = "closing";
        }
      }
      console.log("[recv data]", r);
      debugger; // 3
      return r;
    }
    if (socks[sckt] == "closing" || !socks[sckt]) return -1; // close it
    return "";
  },

I can reach debugger 3. And then where the code goes puzzle me so much! What's the relation between Http.get() and recv()?

debug>step
return r;
^
debug>step
Value returned is ="Hello World!"

---

Posted at 2020-03-25 by Robin

Tue 2020.03.24

It is working as expected as text 'Hello World!' is returned.

As at L20 the string is available in local scope, why not assign it to a global var at that point?

Better:

POST not GET

See link in post #4 and:

http://www.espruino.com/Internet

Concept

https://developer.mozilla.org/en-US/docs/Mozilla/js-ctypes/Using_js-ctypes/Declaring_and_Using_Callbacks

https://codeburst.io/javascript-what-the-heck-is-a-callback-aba4da2deced

https://www.dashingd3js.com/lessons/javascript-callback-functions

https://stackoverflow.com/questions/5263785/how-to-use-callback-function-in-java-script-functions