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:

tar xzvf Django-1.5.4.tar.gz

cd Django-1.5.4

sudo python  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

<VirtualHost *:80>
WSGIDaemonProcess user=djangouser group=djangouser processes=5 threads=1

    DocumentRoot /home/djangouser/web-app
    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

    <Directory /home/djangouser/web-app/apache>
        Order deny,allow
        Allow from all

    <Directory /home/djangouser/web-app/templates>
        Order deny,allow
        Allow from all

    <Directory /home/djangouser/web-app/bmdata/static>
        Order deny,allow
        Allow from all

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

    LogLevel warn

    Alias /static/admin/ /usr/lib/python2.6/site-packages/django/contrib/admin/static/admin/
    Alias /static/ /home/djangouser/web-app/bmdata/static/

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

  • Add django.wsgi 
import os, sys
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 build
sudo python install

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

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

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