Getting data from port 80

Core Library Questions

rubeix

in Core Library Questions • 1 year ago

Hello,

I'm trying to get data from local port 80 into my processing sketch but it is not working.

When i put on my browser my host ip and local port (something like 169.254.186.203:80) i can see what was sent to the local port. So I tryed do get that into processing using the following simple WebClient sketch, but it doen't work.

import processing.net.*;

Client myClient;

int dataIn;

void setup() {

size(200, 200);

// Connect to the local machine at port 80.

// This example will not run if you haven't

// previously started a server on this port

myClient = new Client(this, "169.254.186.203", 80); //my ip and local port

}

void draw() {

if (myClient.available() > 0) {

dataIn = myClient.read();

}

background(dataIn);

}

Somebody can help me with this??

Thanks in advance

Replies(11)

PhiLho

Re: Getting data from port 80

1 year ago

I fear the examples in the Network reference hasn't been updated since a long time (or never worked?).
The examples in Processing Examples > Libraries > Network > HTTPClient works better.
Adapted to your case, it would be:

import processing.net.*;
Client myClient;
char dataIn;
void setup() {
size(200, 200);
// Connect to the local machine at port 80.
// This example will not run if you haven't
// previously started a server on this port
myClient = new Client(this, "192.168.1.111", 80); //my ip and local port
myClient.write("GET / HTTP/1.0\r\n"); // Use the HTTP "GET" command to ask for a Web page
myClient.write("\r\n");
}
void draw() {
if (myClient.available() > 0) {
dataIn = myClient.readChar();
print(dataIn);
}
background((int) dataIn);
}

In your code, you listen to the server, but it won't send data spontaneously. What your browser does, and what my code above does, is to send a request to get a Web page. Then you start receiving data.

rubeix

Re: Getting data from port 80

1 year ago

Hello,

Thanks for your help..

I tryed your code (just modified the ip for my Wifly ip) but it doesn´t work, I'm not getting data on processing.

Which should be the mistake??Do you have any idea?

Thanks again

PhiLho

Re: Getting data from port 80

1 year ago

No idea, as I doubt this port is blocked by a firewall... Double-check the IP address, ensure there is no redirection, stuff like that.
Where is the Web server? On a different computer? That's its IP you have to enter. The IP on the local network, if both are on the same network.

rubeix

Re: Getting data from port 80

1 year ago

Hello,

I already got it working! I applied a server on processing and I can get the values, everithing is fine.

However, after this I would like to build a more complicated Interface, but I got always an error on Client thisClient = myServer.available();. The error is NullPointerException. I already searched about it but the errors I found were not like mine. Someone can tell me how to fix this error? The code is below:

Thanks in advance

import napplet.*;//library to use several skeches on one window

Server myServer;

import processing.net.*;

//Sensor variables from local port

float Temp = 0;

float HR = 0;

void setup() {

size(200, 200);

background(255);

NAppletManager nappletManager = new NAppletManager(this);

//OTHER WINDOWS

//nappletManager.createNApplet("plotsUP", 675, 0);

//nappletManager.createNApplet("Interface_class", 0, 0);

//nappletManager.createNApplet("plotsDOWN", 675, 350);

}

void draw() {

background(255);

getValuesfromWifly();

}

void getValuesfromWifly()

{

// Get the next available client

Client thisClient = myServer.available();

// write the output of the client

if (thisClient !=null) {

//dataIn = thisClient.read();

String whatClientSaid = thisClient.readStringUntil('\n');

if (whatClientSaid != null)

{

whatClientSaid = trim(whatClientSaid); //

float [] infos =float (split(whatClientSaid, ";"));

if (infos.length >=2)

{

Temp = infos [0];

HR = infos [1];

}

}

}

}

PhiLho

Re: Getting data from port 80

1 year ago

See Why do I get a NullPointerException?
Here, you define server but you never initialize it.

rubeix

Re: Getting data from port 80

1 year ago

Hello PhiLho,

Thanks for your answer...In the next code I'm already initializing the server ( myServer = new Server(this, 1234);) but I still getting the same error. I read the link you advised me but it doesn´t present any error like this one I got.

Do you have any idea what should it be now?

Thanks for helping

import napplet.*;//library to use several skeches on one window

Server myServer;

import processing.net.*;

//Sensor variables from local port

float Temp = 0;

float HR = 0;

void setup() {

size(200, 200);

myServer = new Server(this, 1234);

background(255);

NAppletManager nappletManager = new NAppletManager(this);

//OTHER WINDOWS

//nappletManager.createNApplet("plotsUP", 675, 0);

//nappletManager.createNApplet("Interface_class", 0, 0);

//nappletManager.createNApplet("plotsDOWN", 675, 350);

}

void draw() {

background(255);

getValuesfromWifly();

}

void getValuesfromWifly()

{

// Get the next available client

Client thisClient = myServer.available();

// write the output of the client

if (thisClient !=null) {

//dataIn = thisClient.read();

String whatClientSaid = thisClient.readStringUntil('\n');

if (whatClientSaid != null)

{

whatClientSaid = trim(whatClientSaid); //

float [] infos =float (split(whatClientSaid, ";"));

if (infos.length >=2)

{

Temp = infos [0];

HR = infos [1];

}

}

}

}

calsign

Re: Getting data from port 80

1 year ago

Just out of curiosity, why do you declare myServer before importing the network library?

adie.rect..

Re: Getting data from port 80

1 year ago

Thoughts on possible process:
You have nothing coming in so available() is 0.
The number 0 would convert to a string so thisClient(as a string) it isn't null.
So, when you try to read nothing you get the error.

What if instead you saved it as an int and then used, if (thisClient>0){} . This way it stays as a number, which I usually can handle better.

Also, is the data that you are reading a string because if it is actually getting sent as char then it wont be read with readstringuntil leaving you with a null string.

Just some ideas, Im pretty new to this language as well so this may be wrong.

PhiLho

Re: Getting data from port 80

1 year ago

" I read the link you advised me but it doesn´t present any error like this one I got."
You wrote about a NullPointerException, the article explains why you can get this very common error, I am not sure how it isn't addressing your error.

Beside, you are not supposed to have both a Server and a Client in the same sketch. One sketch is the server, the other is the client. If they are both in the same program, there are more efficient ways to share data...

buzlityr

Re: Re: Getting data from port 80

4 months ago

Can you say a little more about "more efficient ways to share data"? I'm trying to write a program that will read and write via TC/IP. I wasn't sure if I needed to (or could) create a Server AND Client on my local machine and similarly on the remote IP location.

rubeix

Re: Getting data from port 80

1 year ago

Hello people,

I already fixed the error, to be honest I dont know how, but it is already working well.

Thanks for your answers

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