Read string from ftp .txt file problem

mihec1986

Read string from ftp .txt file problem

in Integration and Hardware • 1 year ago

Hi!

I made simple applet which continuously reads string data from text file located on FTP. Text file on FTP is updating every two seconds.

I load signed applet on server and lunch it. Applet works fine, also read text file from URL and write down data from text file...but read data only at startup applet, instated every 2 seconds. So, program continue to run, but obviously didn't read data from FTP every cycle.

Applet works fine and read text data every two seconds if I rune code form local disk.

Anny suggestion on that problem? It is possible that first read of text file stay in some kind of buffer and that data is usable during the whole session?

Replies(6)

PhiLho

Re: Read string from ftp .txt file problem

1 year ago

Hard to tell anything without seeing code...
You don't really need a FTP library to read data from a FTP server, such library is more useful to list data, to upload stuff, etc.
For reading, the following lines work:

String[] lines = loadStrings("ftp://ftp.cs.duke.edu/.welcome.msg");
println(lines);

mihec1986

Re: Read string from ftp .txt file problem

1 year ago

Here is the code concept:

public String[] read_FTP;
PFont font1;

void setup()
{

      size(200, 200);
      frameRate(1);
      font1 = loadFont("Calibri-48.vlw");
      textFont(font1);

}

void draw()
{
      // Read file from FTP
      read_FTP = loadStrings("http://myFTPxxxxx/i_o_data.txt");
      // Draw data
      if(read_FTP != null)text(read_FTP[0], 30, 30);
      else println("error");
}

My code is a little bit larger, because it write out a couple of parameters saved on text file.

PhiLho

Re: Read string from ftp .txt file problem

1 year ago

Have look at the Java console, perhaps you have an exception or an error message.
And don't use frameRate() to control the frequency of the readings, use millis() instead.

mihec1986

Re: Read string from ftp .txt file problem

1 year ago

Because of 2 minutes interval uploading text file on FTP, and every second reading the same file from FTP...sometimes it came to exception of "file is not readable or exsistable". This problem was solved with condition if the reading of file on FTP return "null". If it not, read file and draw the read results.

Like I said, program on remote location work normal, just it wont reed text file from FTP more the once. If I run program from local location, program work normal and also normal reed text file from FTP.

mihec1986

Re: Read string from ftp .txt file problem

1 year ago

I browse older topic about my problem and found something familiar.

On that link there is exactly the same problem that I have. So, there is problem with java cache. User "fry" suggest to trick java cache with added "?" and some random numbers on the back of the url address when to load string. I tried that trick but still no good.

So the main problem is how to continuously load and write down some continuously changing text data from FTP in applet located on web page?

Has anybody have ideal or suggestion how to solve this problem?

mihec1986

Re: Read string from ftp .txt file problem

1 year ago

Hello again!

I finally solve problem and figure out what was mentioned with "?" in URL address of reading data from FTP (mentioned in upper post).

If you want load .txt data from FTP or locale/remote location into your applet located on FTP, you need add your loading address "?" and "random number(s)". In my case I generate random number with function "second()".

Example: load data located on FTP "yourFTPlocation/i_o_data.txt" to string array " load_data_ftp ":

String[] load_data_ftp = loadStrings("http://yourFTPlocation/i_o_data.txt?" + second());

The whole point with "?" and added random numbers is to trick your browser to load data from FTP every time applet need to read data form FTP instate load data form browser cache.

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