Stuff I do: September 2013

Sunday, 29 September 2013

CSS Positioning

The display property can be set to:

block - takes up entire width of the html page and does NOT let any other elements sit next to it.
inline-block - allows other elements to sit next to it self in the same line
inline - allows elements to sit in the same line. Useful only for block elements like <p>, as otherwise the element loses its dimensions
none - the element is not displayed.

To place an element in the center of the page use "margin:auto" as the style.
We can use negative margin/padding to move element off the page as well.
When you float an element on the page, you're telling the webpage: "I'm about to tell you where to put this element, but you have to put it into the flow of other elements." This means that if you have several elements all floating, they all know the others are there and don't land on top of each other.
If you tell an element to clear: left, it will immediately move below any floating elements on the left side of the page; it can also clear elements on the right. If you tell it to clear: both, it will get out of the way of elements floating on the left and right!
If you don't specify an element's positioning type, it defaults to static. This just means "where the element would normally go." If you don't tell an element how to position itself, it just plunks itself down in the document.
The first type of positioning is absolute positioning. When an element is set to position: absolute, it's then positioned in relation to the first parent element it has that doesn't have position:static. If there's no such element, the element with position: absolute gets positioned relative to <html>.
Relative positioning is more straightforward: it tells the element to move relative to where it would have landed if it just had the default static positioning.
Finally, fixed positioning anchors an element to the browser window—you can think of it as gluing the element to the screen. If you scroll up and down, the fixed element stays put even as other elements scroll past.

Wednesday, 25 September 2013

Setting up Django Web-app on amazon linux - AWS micro instance

SSH into your linux AWS system using a command like this:

chmod 400 ~/pvtkey.pem
ssh -i ~/pvtkey.pem ec2-user@<AWS-instance-public-IP>

Install Apache httpd server:

sudo yum install httpd
sudo /etc/init.d/httpd start OR service httpd start

sudo chkconfig httpd on

You can check what is installed with RPM

rpm -qa


Install Django:

wget https://www.djangoproject.com/m/releases/1.5/Django-1.5.4.tar.gz
tar xzvf Django-1.5.4.tar.gz

cd Django-1.5.4

sudo python setup.py  install

Install mod_wsgi:

sudo yum install mod_wsgi

Add a new user for django:


sudo useradd djangouser
su - djangouser

Edit http.conf file:

sudo vi /etc/httpd/conf/httpd.conf

NameVirtualHost *:80

WSGIDaemonProcess ec2-54-200-XXX-XXX.us-west-2.compute.amazonaws.com user=djangouser group=djangouser processes=5 threads=1

WSGIProcessGroup ec2-54-200-XXX-XXX.us-west-2.compute.amazonaws.com

DocumentRoot /home/djangouser/web-app

ServerName ec2-54-200-XXX-XXX.us-west-2.compute.amazonaws.com

ErrorLog /home/djangouser/web-app/apache/logs/error.log

CustomLog /home/djangouser/web-app/apache/logs/access.log combined

WSGIScriptAlias / /home/djangouser/web-app/apache/django.wsgi

Order deny,allow

Allow from all

</Directory>

Order deny,allow

Allow from all

</Directory>

Order deny,allow

Allow from all

</Directory>

<Directory /usr/lib/python2.6/site-packages/django/contrib/admin/static/admin/>
Order deny,allow
Allow from all
</Directory>

LogLevel warn

Alias /static/admin/ /usr/lib/python2.6/site-packages/django/contrib/admin/static/admin/

Alias /static/ /home/djangouser/web-app/bmdata/static/

</VirtualHost>

WSGISocketPrefix /home/djangouser/web-app/apache/run/

Add django.wsgi

import os, sys
sys.path.append('/home/djangouser/web-app')
os.environ['DJANGO_SETTINGS_MODULE'] = 'BMonitor.settings'
import django.core.handlers.wsgi

application = django.core.handlers.wsgi.WSGIHandler()

Installing python libs for matplotlib and numpy on AWS

sudo yum install gcc-c++

sudo yum install gcc-gfortran

sudo yum install python-devel

sudo yum install atlas-sse3-devel

sudo yum install lapack-devel

sudo yum install libpng-devel

sudo yum install freetype-devel

sudo yum install zlib-devel

tar xzvf matplotlib-1.3.1.tar.gz

cd matplotlib-1.3.1

sudo python setup.py build

sudo python setup.py install

References: http://pragmaticstartup.wordpress.com/2011/04/02/non-techie-guide-to-setting-up-django-apache-mysql-on-amazon-ec2/
https://code.google.com/p/modwsgi/wiki/IntegrationWithDjango

Saturday, 7 September 2013

Using wget to download an ASP site

You can download an ASPX site, which asks for username/password for log in as follows:

First provide the username/password to the login page and save the cookie file.

wget --mirror -r \
--user-agent="" \
--keep-session-cookies --save-cookies cookies.txt \
--post-data '__VIEWSTATE=%2FwEPDwULLTE3MDc5MjQzOTdkZIP%2Fxc105yfz2jGFj4Nd3tPvrEeNara43fIRI5oAW%2Bwv&__EVENTVALIDATION=%2FwEWBAKisoyCAwLB2tiHDgK1qbSRCwL2k8O9DUQa5owMFDWzFnBoIDusNkznjB65a6zRyNETOEZfBM1o&txtUser=admin&txtPassword=admin&login_btn=Sign+In' \
-E -k -p http://www.xyz.com/Login.aspx

Then you can access other pages in the next step using the above generated cookie files.

wget --mirror -r \
--user-agent="" \
--keep-session-cookies --load-cookies cookies.txt \
-E -k -p http://www.xyz.com/Index.aspx

For details of the options, refer to the WGET manual i.e "man wget" :)