sharedCanvasClient and sharedCanvasServer problem

Core Library Questions

clankill3r

sharedCanvasClient and sharedCanvasServer problem

in Core Library Questions • 2 years ago

In processing examples > libraries > network there is,

sharedCanvasClient and,
sharedCanvasServer

Sometimes i get an array out of bounds exeption, i tested with a println and i figured out that sometimes it sends not the complete String.
If if send the string "test" for example then it receives sometimes just "te".
Why does this occur?

I know i can solve by checking the length of the input but if someone can explain why this happens then that would be nice.

Replies(4)

anchnk

Re: sharedCanvasClient and sharedCanvasServer problem

2 years ago

I've never noticed such problem with that example.
Did you modified the example or just use vanilla code ?
Where did you put your println function ?

clankill3r

Re: sharedCanvasClient and sharedCanvasServer problem

2 years ago

First of all a edit script:

Server:

import processing.net.*;
Server s;
Client c;
void setup()
{
size(450, 255);
frameRate(50);
s = new Server(this, 12345); // Start a simple server on a port
}
void draw() {
c = s.available();
if (c != null) {
String m = c.readString();
println("m on server " + m);
}
}

Client:

import processing.net.*;
Client c;
void setup() {
size(450, 255);
frameRate(50);
c = new Client(this, "127.0.0.1", 12345); // Replace with your server's IP and port
}
void draw() {
String m = "";
m += millis();
println("m on client " + m);
c.write(m);
}

the output looks like this (sometimes no return?): (can be a processing bug, don't know)

m on client 485

m on server 465

m on server 485

m on client 505

m on server 505m on client 525

m on server 525

m on client 546

m on server 546m on client 565

m on client 586

m on server 565

m on client 605

m on server 586

m on server 605m on client 625

For the rest, i'm at home and here the script (default unedited from examples) runs fine. It happens on school that it goes wrong, i will drop the error that occurs here asap.

clankill3r

Re: sharedCanvasClient and sharedCanvasServer problem

2 years ago

I just noticed that if i set the framerate to 50 then i can recreate a error (faster?):

the error is on this line in the server script

input = input.substring(0, input.indexOf("\n")); // Only up to the newline

this is the error:

StringIndexOutOfBoundsException: String index out of range: -1

And doing another test i got the error on this line:

line(data[0], data[1], data[2], data[3]);

where the error is:

ArrayIndexOutOfBoundsException: 2

anchnk

Re: sharedCanvasClient and sharedCanvasServer problem

2 years ago

OK, i can reproduce the exception too on my work computer.
I don't think that's a network library bug. I think that's more how this example is designed but i'm not really sure.
I think sometimes some data aren't correctly received by the server because of the framerate fluctuation (or because of the library thread synchronisation).

I'll try to dig into it deeper (if i find some time).
If someone else wanna help too, any help is welcome.

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