what i've learned

csc309 webserver & javascript cookies

Fri, 12 Feb 2010 16:26:15 -0500

Here is the pickling and cookie webserver example using webpy that I presented in tutorial:

#!/usr/bin/env python

import os
import web
from pickle import load, dump

urls = (
    '/', 'Index'
)
app = web.application(urls, globals())

# global session store & session id 
SESSION_COUNT = 0
SESSIONS = {}


# methods to save & load data to files to persist
# session changes across restarts & crashes
data_fn = 'data.pkl'
def save_data():
    fp = open(data_fn, 'w')
    dump( (SESSIONS, SESSION_COUNT) , fp)
    fp.close()
def load_data():    
    if not os.path.isfile(data_fn): return
    global SESSIONS, SESSION_COUNT
    fp = open(data_fn, 'r')
    SESSIONS, SESSION_COUNT = load(fp)
    fp.close()

# restore our session data
load_data()

def parse_cookies():
    cookies_str = web.ctx.env['HTTP_COOKIE']
    return dict([ c.strip().split('=')
                  for c in cookies_str.split(';')])

class Index(object):
    def GET(self):
        web.header('Content-Type','text/html')

        session = {}

        # see if the user has our cookie already
        if 'HTTP_COOKIE' in web.ctx.env:
            cookies = parse_cookies()
            for name, val in cookies.items():
                web.debug('got cookie: %s = %s' % (name, val))

            # grab the session based on the user's cookie
            if 'session_id' in cookies:
                web.debug('got session id')
                session = SESSIONS[cookies['session_id']]

        # check if we got a session, if not create a new one
        if not session:
            web.debug('missing session, creating new session')
            global SESSION_COUNT
            expires_date = 'Fri, 11-Dec-2010 11:59:59 GMT'
            web.header('Set-Cookie', 'session_id=%s;'
                        ' expires=%s;'
                        % (expires_date, SESSION_COUNT))
            SESSIONS[str(SESSION_COUNT)] = session
            SESSION_COUNT += 1

        # update the session
        session['visits'] = session.setdefault('visits', 0)+1
        save_data()

        return (str(web.ctx.env) + 
                " You've visited %s times!"
                % session['visits'])


    def POST(self):
        self.GET()


if __name__ == "__main__":
    # run the webserver    
    app.run()

And here is the example of using cookies in Javascript:

// Cookies in Javascript

// The manual (tedious) way to set a cookie
document.cookie = ‘ppkcookie1=testcookie;' +
    ' expires=Thu, 2 Aug 2010 20:47:11 UTC; path=/’;

// The easy way
// from http://www.quirksmode.org/js/cookies.html

// if days == 0, the cookie expires when
// the user closes their browser
function createCookie(name,value,days) {
    if (days) {
	var date = new Date();
	date.setTime(date.getTime()+(days*24*60*60*1000));
	var expires = “; expires=”+date.toGMTString();
    } else var expires = “”;
    document.cookie = name+”=”+value+expires+”; path=/”;
}

function readCookie(name) {
    var nameEQ = name + “=”;
    var ca = document.cookie.split(‘;’);
    for(var i=0;i < ca.length;i++) {
	var c = ca[i];
	while (c.charAt(0)==’ ‘) c = c.substring(1,c.length);
	if (c.indexOf(nameEQ) == 0) {
            return c.substring(nameEQ.length,c.length);
        }
    }
    return null;
}

function eraseCookie(name) {
    createCookie(name,”“,-1);
}

find files in linux by modification time

Tue, 08 Sep 2009 16:55:36 -0400

find files in linux by modification time

upgrading Ubuntu 8.04 to 8.10 to 9.04

Wed, 29 Apr 2009 08:49:00 -0400

I finally upgraded Ubuntu on my IBM T43 laptop. I was waiting for 9.04 because I heard lots of problems about the 8.04 to 8.10 upgrade process but then I found out I had to upgrade to 8.10 before I could get to 9.04 - so it goes.

The upgrade went smoother than my previous one though.

Sound:
sound stopped working but I was expecting this because PulseAudio caused this in the previous upgrade, luckily I found this tutorial on keeping the PulseAudio beast at bay which worked like a charm. Sadly, I no longer have on screen volume indicators when I change the volume using the extra keyboard keys but apparently this is a known issue and its a very minor annoyance.

Graphics:
All my Compiz settings seem to have been reset but that should only take a minute to re-configure. Also my text rendering settings were reset and everything looked too sharp and pixelated until I re-activated sub-pixel smoothing. On the plus side, I’m getting all the fancy effects without the proprietary ATI driver warning (I think they open-sourced their driver some time ago).

Networking:
Wireless didn’t work at first because apparently madwifi is a restricted driver now that I had to activate manually. This took me a minute to figure out since there was not auto-notification of this.

Firefox:
Firefox went from 3.0.8 to 3.0.10 and all my sessions and extensions seemed to survive perfectly except Tabkit which now won’t do its awesome hierarchical tab display or event the multi-row tab display. This is by far the most annoying issue since I’ve become addicted to hierarchical tabs. I also had to re-install Flash player and I couldn’t get the auto-prompted installer to work so I had to download the debian package direct from Adobe and run it.

Hibernation & Sleeping are finally working again.

electric bikes review

Mon, 20 Apr 2009 12:45:00 -0400

there are lots of interesting electric bikes. i found a good comparison at http://www.electricvehiclesnw.com/main/ebike-comp.htm

i like the following models:

Giant Twist DX & Twist Lite - $2,100 & $1,700
eZee Forza - $2,200
iZip - one of the cheaper ones at $600 because it uses SLA and not Lithium Ion batteries which are cheaper and shorter lasting and heavier
Optibike - the 850XLi is a $10k monster although they have some lower end models (http://shop.optibike.com/)
also an interesting folding bike, the EcoBike Vatavio at around $1,500

i prefer the Lithium Ion models that look like normal bikes

also read that electric bike motors limited to 20mph by US regulations.. what a shame

there are also a number of kits to turn your normal bikes into electric bikes
one of the more innovative ones seems to be the StokeMonkey (http://cleverchimp.com/products/stokemonkey/)

treehugger shows off some of the bigger, faster, more expensive electric scooters:
http://www.treehugger.com/files/2008/06/7-best-electric-scooters-prototypes-production-models.php

Basic XSL & Ajax Tutorial

Thu, 09 Apr 2009 19:24:29 -0400

Some simple programming examples of XSL & AJAX:

XSL (eXtensible Stylesheet Language) (see http://www.w3schools.com/xsl/ )
XSL is a style sheet language for XML documents. It describes how to display an XML document of a given type, so in a way it is similar to CSS but it adds a transformation language for XML documents called XSLT which is most often used to transform XML data into HTML but can transform between any two XML representations.

Example XML Data:

<?xml version=”1.0” encoding=”ISO-8859-1”?>
<?xml-stylesheet type=”text/xsl” href=”cdcatalog.xsl”?>
<catalog>
<cd>
<title>Empire Burlesque</title>
<artist>Bob Dylan</artist>
<country>USA</country>
<company>Columbia</company>
<price>10.90</price>
<year>1985</year>
</cd>
.
.
</catalog>

Example XSL Template (XSLT):

<?xml version=”1.0” encoding=”ISO-8859-1”?>
<xsl:stylesheet version=”1.0”
xmlns:xsl=”http://www.w3.org/1999/XSL/Transform”>

<xsl:template match=”/”>
<html>
<body>
<h2>My CD Collection</h2>
<table border=”1”>
<tr bgcolor=”#9acd32”>
<th align=”left”>Title</th>
<th align=”left”>Artist</th>
</tr>
<xsl:for-each select=”catalog/cd”>
<tr>
<td><xsl:value-of select=”title”/></td>
<td><xsl:value-of select=”artist”/></td>
</tr>
</xsl:for-each>
</table>
</body>
</html>
</xsl:template>

</xsl:stylesheet>

Example Output: http://www.w3schools.com/xsl/cdcatalog_with_xsl.xml

(examples from http://www.w3schools.com/xsl/cdcatalog_with_xsl.xml )

In the exapmle above, the browser automatically converts xml into html. Typically, you would convert it yourself on the server side in Java or on the client side with Javascript.
on client: http://www.w3schools.com/xsl/xsl_client.asp
on server: http://www.w3schools.com/xsl/xsl_server.asp

AJAX (Asynchronous Javascript And Xml) (see http://www.w3schools.com/Ajax/default.asp )
AJAX allows you to get responses from the webserver without reloading the page. It can be used asynchronously or synchronously (asynch is best, define a handler function). Useful for form submission, live updates, changing page content on actions. It is quicker than page reloads because you send less data over the wire, you only have to load some parts of the page once and the rest can be fetched via AJAX. But be wary of breaking browser history and the back button which work by default with page reloads but require extra effort to work properly with AJAX.

AJAX Example:

<html>
<body>

<script type=”text/javascript”>
function ajaxFunction() {
// cross browser compatible XMLHttpRequest creation
var xmlHttp;
try {
// Firefox, Opera 8.0+, Safari
xmlHttp=new XMLHttpRequest();
} catch (e) {
// Internet Explorer
try {
xmlHttp=new ActiveXObject(“Msxml2.XMLHTTP”);
} catch (e) {
try {
xmlHttp=new ActiveXObject(“Microsoft.XMLHTTP”);
} catch (e) {
alert(“Your browser does not support AJAX!”);
return false;
}
}
}
// setup handler on success
xmlHttp.onreadystatechange = function() {
if(xmlHttp.readyState == 4) {
document.myForm.time.value = xmlHttp.responseText;
}
}
// set request parameters (similar to form tag parameters)
xmlHttp.open(“GET”,”time.asp”,true); // 3rd is asynch
xmlHttp.send(null); // null because we aren’t using POST data
}
</script>

<form name=”myForm”>
Name: <input type=”text”
onkeyup=”ajaxFunction();” name=”username” />
Time: <input type=”text” name=”time” />
</form>

</body>
</html>

Or if you use jQuery: http://docs.jquery.com/Ajax/jQuery.ajax

function ajaxFunction() {
$.ajax({
type:’GET’,
url:’time.asp’,
success: function(responseText) {
document.myForm.time.value = responseText;
}
});
}

csc309 tomcat & js cookies

Thu, 12 Mar 2009 19:52:00 -0400

# Using Tomcat
# the following are commands to run on cdf

# download Tomcat
wget http://apache.sunsite.ualberta.ca/tomcat/tomcat-6/v6.0.18/bin/apache-tomcat-6.0.18.tar.gz
tar xzf apache-tomcat-6.0.18.tar.gz

# configure Tomcat
cd apache-tomcat-6.0.18
pico conf/server.xml
# change 8080’s to your assigned port number

# run Tomcat
bash
export JAVA_HOME=/local/packages/jdk1.6.0_07/
bin/startup.sh
# view http://localhost:PORT_NUMBER/ in your browser on cdf to test that it works

# get a sample application
cd webapps
wget http://tomcat.apache.org/tomcat-6.0-doc/appdev/sample/sample.war
# view http://localhost:PORT_NUMBER/sample in your browser on cdf to test that the sample app works
cd ../

# stop Tomcat
bin/shutdown.sh

// Cookies in Javascript

// The manual (tedious) way to set a cookie
document.cookie = ‘ppkcookie1=testcookie; expires=Thu, 2 Aug 2010 20:47:11 UTC; path=/’;

// The easy way
// from http://www.quirksmode.org/js/cookies.html

// if days == 0, cookie expires when the user closes their browser
function createCookie(name,value,days) {
if (days) {
var date = new Date();
date.setTime(date.getTime()+(days*24*60*60*1000));
var expires = “; expires=”+date.toGMTString();
} else var expires = “”;
document.cookie = name+”=”+value+expires+”; path=/”;
}

function readCookie(name) {
var nameEQ = name + “=”;
var ca = document.cookie.split(‘;’);
for(var i=0;i < ca.length;i++) {
var c = ca[i];
while (c.charAt(0)==’ ‘) c = c.substring(1,c.length);
if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
}
return null;
}

function eraseCookie(name) {
createCookie(name,”“,-1);
}

Running Apache

see my last tutorial post for instructions on running Apache

how to keep track of your (business) reputation

Thu, 12 Mar 2009 00:09:09 -0400

Google Alerts - get notified as Google updates its search index

TweetBeep - get notified as people tweet about you

BackType - get notified about comments on blogs and websites

django middleware

Tue, 10 Mar 2009 10:39:55 -0400

might be useful for other wsgi projects

but are these Django specific..?

functional languages i need to check out

Mon, 09 Mar 2009 19:04:19 -0400

went through the Wikipedia Category on functional languages the other week and I found a bunch of interesting languages I want to check out

Scala JVM-based, java with less syntax + functional aspects

F# Microsoft’s .NET functional language (only interesting to me if the Mono implementation is complete)

Clojure JVM-based, may be good for concurrent programming

Boo python-like .NET language with Mono support

also stumbled upon some projects to build operating systems with functional languages: Kinetic, House, Singularity (found a Squeak one too: SqueakNOS)

maybe someday we’ll be running operating systems without side effects :P

continuation based web frameworks

Mon, 09 Mar 2009 17:56:00 -0400

only the cool languages have them :)

Seaside for Smalltalk / Squeak

Continue for PLT Scheme

Weblocks for Lisp

UnCommon Web for Common Lisp

some interesting parts of Python Paste

Mon, 16 Feb 2009 04:42:13 -0500

directory diffs

mapping urls to different wsgi apps

internal app requests via internal redirects & forwards

gzipper middleware

log requests in apache log format

authentication

web app exception handling with interactive browser-based debugging (very cool)

file monitor to restart server when code changes

dictionary that can hold multiple values at each key (multidict)

framework for testing wsgi & web apps 1 2 3

applying filters to wsgi app output

run php via wsgi

support for intermediate responses to long running requests

yet another ini parser/generator

fetching & displaying favicons

Wed, 11 Feb 2009 15:25:12 -0500

via Google:

http://www.google.com/s2/favicons?domain=www.wired.com

produces

csc309 apache & dhtmlx

Thu, 05 Feb 2009 22:25:00 -0500

to setup apache on cdf:

grab the apache.tar.gz file from the Student Guide on the course site (there is also an apache.htm page which has instructions similar to these)
extract apache.tar.gz to your home directory on cdf which creates a folder called apache
run the apache/bin/start.sh file to start apache (and apache/bin/stop.sh to stop apache before you logout of cdf)
when prompted use the port you have been assigned, see the CSC309-ports.txt file in the Student Guide

and voila! your personal apache server should be running, you can view it in a browser running on cdf at the address: http://localhost:[your port]/

the start.sh file you ran set up your apache environment in your home directory, not to be confused with the directories in the apache folder

so your html/css/js/xml/etc go in the htdocs folder in your home directory

also, here is the DHTMLX example page i showed in tutorial for your reference

(check out my DOM & Javascript post in case you missed that tutorial)

no famous CS blogs?

Sun, 01 Feb 2009 14:30:59 -0500

thought i might try to expand my horizons by following what famous researchers/professors in CS are thinking and doing via their blogs. you know Turing Award winners and such

alas, i could find practically none of them blogging… sad, the profession that creates the web isn’t fully utilizing it

in the end i’ve subscribed to Mark Guzdial’s Amazon blog and i found a number of natural language processing blogs but they didn’t spark my interest

anyone know of some blogs that i missed?

upgrading Ubuntu Server

Sat, 31 Jan 2009 13:10:09 -0500

upgrading Ubuntu Server:

see the section at the bottom of the page for upgrading without the update-manager gui

get linux IP address in a shell script

Sat, 31 Jan 2009 13:08:05 -0500

get linux IP address in a shell script

port forwarding with a VirtualBox guest OS

Sat, 31 Jan 2009 13:06:44 -0500

port forwarding with a VirtualBox guest OS

using screen

Sat, 31 Jan 2009 13:00:46 -0500

* screen
  o Run a new screen session
* screen -R
  o Reattach to a previously detatched session
* Ctrl-a c
  o Create a new window.
* Ctrl-a k
  o Kill the current window - after confirmation
* Ctrl-a Ctrl-a
  o Switch to the other window
* Ctrl-a S
  o Split the current window in two.
* Ctrl-a TAB
  o Move between split sections of the screen.
* Ctrl-a A
  o Give the the current window a name.
* Ctrl-a "
  o List all windows - change the window with the arrow keys

basic sed

Sat, 31 Jan 2009 12:54:00 -0500

file global replace using regex (old_file should not be the same as new_file)

sed ‘s/old/new/; s/old2/new2/’ old_file > new_file

from Oracle sed article

git & github

Thu, 29 Jan 2009 22:27:22 -0500

clone a repository to work on locally

git clone git://github.com/user/project.git

add a repository for pushing & pulling

git remote add <repo alias> git://github.com/user/project.git

see available repositories

git remote

pull changes from another repository

git pull <repo alias> <branch>

commit changes, auto-adding changed files

git commit -a -m “comment”

push changes to my repository

git push <repo (defaults to origin)> <branch (defaults to master)>

configure for github account

git config —global user.email <email>

other tidbits

don’t need to set files to resolved once you resolve conflicts