Python and FTP

That page gives a very short simple Python code to FTP a file. I tried adapting it to send a little text file to my Telus webspace.

Note that {username} and {password} were replaced with my actual user name and password.

import ftplib

ftp = ftplib.FTP('ftp.shaw.ca','{username}','{password}') # Connect
fp = open('try.txt','rb') # file to send
ftp.storbinary('STOR try.txt', fp) # Send the file

fp.close() # Close file and FTP
ftp.quit()

It worked! The python code was put in a file called ftp.py. \ I also created a little text file with a short message called try.txt.

The result in this inline window shown here at the far right. You could also look at it using this link http://members.shaw.ca/danpeircenotes/try.txt. This would be more interesting if I the python code created some content generated on the fly. Perhaps temperature data. For a start I'd try just sending the time time of day.

Sending Time of Day

import ftplib
from time import strftime


def uploadfile():
    ftp = ftplib.FTP('ftp.shaw.ca','{username}','{password}') # Connect
    fp = open('time.txt','rb') # file to send
    ftp.storbinary('STOR time.txt', fp) # Send the file

    fp.close() # Close file and FTP
    ftp.quit()

def buildfile():
    f = open('time.txt', 'w')
    f.write(strftime("%Y-%m-%d %H:%M:%S"))
    f.close()

buildfile()
uploadfile()

The result can be seen at http://members.shaw.ca/danpeircenotes/time.txt. The date and time represent the last time the file was last updated. In addition to time sensor date could be included.

Rather than overwriting the file each time it is possible to append the file so that each update time is kept and a list of update times is created.

import ftplib
from time import strftime


def uploadfile():
    ftp = ftplib.FTP('ftp.shaw.ca','{username}','{password}') # Connect
    fp = open('time_a.txt','rb') # file to send
    ftp.storbinary('STOR time_a.txt', fp) # Send the file

    fp.close() # Close file and FTP
    ftp.quit()

def buildfile():
    f = open('time_a.txt', 'a')
    f.write(strftime("%Y-%m-%d %H:%M:%S"))
    f.write('\n')
    f.close()

buildfile()
uploadfile()

Dynamically Creating Static HTML

Previous examples created simple text files. It is also possible to create HTML files. There are a variety of techniques for this. I decided to try the technique shown on the following website.

I also decided to change the template to a basic html5 template to be much like my index.html page on my www3.telus.net site. The intent is to have a page that is still friendly to mobile devices as well as bigger computers. The other modification of the webtemplates.html example is that I have included the ftp upload as given in my previous examples rather than opening a web browser to view the result.

import ftplib
from time import strftime

# this section is the template. It is a multi-line string assigned to the variable pageTemplate.  Inside
#    the string is a placeholder {time} for the dynamic time string.
pageTemplate = '''
<!DOCTYPE html> 
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=2.0, user-scalable=yes" />
<link media="Screen" href="test.css" type="text/css" rel="stylesheet" />
<link media="handheld, only screen and (max-width: 480px), only screen and (max-device-width: 480px)" href="mobile.css"

type="text/css" rel="stylesheet" />

<title>Dynamic Generation of Static HTML5 and Automatic FTP Upload</title>
</head>
<body>
  <div id="header"><hr />
    <h1>Dynamic Generation of Static HTML5 and Automatic FTP Upload</h1><hr />
  </div>
  <div id="container">
  <div id="content">
  <p>The date and time this file was last updated was {time}
  </p>
  </div>
  </div> <!-- container -->
  <div id="footer" ><hr /> <a href="#header">Back to top of page</a><hr />
  </div>
</body>
</html>'''  # NEW note '{time}' seven lines up


def strToFile(text, filename='time.html'):
    """Write a file with the given name and the given text."""
    output = open(filename,"w")
    output.write(text)
    output.close()

def uploadfile():
    ftp = ftplib.FTP('ftp.shaw.ca','{username}','{password}') # Connect
    fp = open('time.html','rb') # file to send
    ftp.storbinary('STOR time.html', fp) # Send the file

    fp.close() # Close file and FTP
    ftp.quit()

def main():    # NEW
    time = strftime("%Y-%m-%d %H:%M:%S") 
    contents = pageTemplate.format(**locals())   # this puts the variable time into the {time} space holder in the string
    strToFile(contents) 
    uploadfile()

main()

Python Pickle

It is probably unnecessary to upload data to the web server too frequently. It would be more practical to store data locally on the Raspberry Pi and update the server just a few times a day. The data can be stored in data structures in ram but should be saved to files periodically to avoid loss of data. Pickel can be used when saving a data structure.

Data Exchange Formats

Often it is not ideal to convert data directly to html. One may want to store the data in a database or data exchange format.