Therefore Systems http://www.thereforesystems.com a learning effort by Deepak Kapoor Wed, 16 May 2012 01:12:57 +0000 en hourly 1 http://wordpress.org/?v=3.3.1 ThereforeSystemshttp://feedburner.google.comhttp://creativecommons.org/licenses/by-nc-nd/2.0/http://creativecommons.org/licenses/by-nc-nd/2.0/http://creativecommons.org/images/public/somerights20.gifSome Rights ReservedOneDotNetWayhttp://feedburner.google.com Cloudera VirtualBox boot error NET: Registered protocol family 2 http://feedproxy.google.com/~r/OneDotNetWay/~3/3-DVZGwE-zY/ http://www.thereforesystems.com/cloudera-virtualbox-boot-error-net-registered-protocol-family-2/#comments Wed, 16 May 2012 01:11:17 +0000 Deepak http://www.thereforesystems.com/?p=1231 I downloaded Cloudera CDH3 Virtual Machine for VirtualBox to have a readymade Hadoop environment to experiment with. While booting the VM I got an error and the boot sequence stalled.

 

The issue here is that IOAPIC is disabled for this VM. You can find out more about IOAPIC here.

To [...]

Cloudera VirtualBox boot error NET: Registered protocol family 2 is a post from: Therefore Systems

]]> I downloaded Cloudera CDH3 Virtual Machine for VirtualBox to have a readymade Hadoop environment to experiment with. While booting the VM I got an error and the boot sequence stalled.

Cloudera CDH boot error

 

The issue here is that IOAPIC is disabled for this VM. You can find out more about IOAPIC here.

To enable IOAPIC, power off your virtual machine. Go to settings –> System. Click on Motherboard tab and check Enable IO APIC.

Cloudera VirtualBox image settings

After this Cloudera image boots fine.

Cloudera CDH3

Cloudera VirtualBox boot error NET: Registered protocol family 2 is a post from: Therefore Systems

]]> http://www.thereforesystems.com/cloudera-virtualbox-boot-error-net-registered-protocol-family-2/feed/ 0 http://www.thereforesystems.com/cloudera-virtualbox-boot-error-net-registered-protocol-family-2/http://feedproxy.google.com/~r/ThereforeSystems/~3/ODdoUB-zUVA/ Error Installing ASP.NET MVC 4 with Web Platform Installer http://feedproxy.google.com/~r/OneDotNetWay/~3/E-rop5ZS5Yk/ http://www.thereforesystems.com/error-installing-asp-net-mvc-4-with-web-platform-installer/#comments Tue, 24 Apr 2012 00:29:27 +0000 Deepak http://www.thereforesystems.com/?p=1223 I’m starting this post with a rant. Here it goes. Web Platform Installer has got to be the most pathetic piece of crap ever produced by Microsoft. It just does not work. I can’t understand how they are able to push out such a piece of garbage. I’m angry, and I have my reasons. So [...]

Error Installing ASP.NET MVC 4 with Web Platform Installer is a post from: Therefore Systems

]]> I’m starting this post with a rant. Here it goes. Web Platform Installer has got to be the most pathetic piece of crap ever produced by Microsoft. It just does not work. I can’t understand how they are able to push out such a piece of garbage. I’m angry, and I have my reasons. So I want to play with ASP.NET MVC 4. I go to the website and I attempt an install. After about 5 minutes Web Platform Installer shows me this:

Web Platform Installer Error

Failed to Install? Why?

You are sorry? You’ve got to be kidding me.

Now I’ve had my adventures with Web Platform Installer in the past. I should not have bothered with it again. Next time I’m not touching this thing. Rant over.

To install it without raising your blood pressure, follow this link:

http://download.microsoft.com/download/3/1/0/310C7C02-9E25-4A11-88E0-4CEC53556CC1/AspNetMVC4Setup.exe

Error Installing ASP.NET MVC 4 with Web Platform Installer is a post from: Therefore Systems

]]> http://www.thereforesystems.com/error-installing-asp-net-mvc-4-with-web-platform-installer/feed/ 0 http://www.thereforesystems.com/error-installing-asp-net-mvc-4-with-web-platform-installer/http://feedproxy.google.com/~r/ThereforeSystems/~3/2trKnaDIq4k/ Meaningless number: 230,000,000 http://feedproxy.google.com/~r/OneDotNetWay/~3/nri28KOaI08/ http://www.thereforesystems.com/meaningless-number-230000000/#comments Thu, 12 Apr 2012 01:53:58 +0000 Deepak http://www.thereforesystems.com/?p=1219 Search for Sydney weather and Google says that it has found 230,000,000 results. It also takes pride in telling us that it took 0.16 seconds to complete the task. Am I impressed? Totally.

 

 

So let’s just see what Google has to show me on page 230,000.

 

 

WTF?

[...]

Meaningless number: 230,000,000 is a post from: Therefore Systems

]]> Search for Sydney weather and Google says that it has found 230,000,000 results. It also takes pride in telling us that it took 0.16 seconds to complete the task. Am I impressed? Totally.

 

Google search for Sydney weather. 230,000,000 results found.

 

So let’s just see what Google has to show me on page 230,000.

 

Google search for Sydney weather. Cannot show more than 1000 results.

 

WTF?

What is the point of bragging about those 230,000,000 results in 0.16 seconds when you will only show 1000 of those results?

Bad Google, bad bad Google.

Meaningless number: 230,000,000 is a post from: Therefore Systems

]]> http://www.thereforesystems.com/meaningless-number-230000000/feed/ 3 http://www.thereforesystems.com/meaningless-number-230000000/http://feedproxy.google.com/~r/ThereforeSystems/~3/iijH5lhD4Xs/ Enable GZip Compression in Django http://feedproxy.google.com/~r/OneDotNetWay/~3/ITJtkhWbYwQ/ http://www.thereforesystems.com/enable-gzip-compression-in-django/#comments Mon, 26 Mar 2012 04:13:59 +0000 Deepak http://www.thereforesystems.com/?p=1196 GZip compression reduces size of payload sent to browser which in turn increases performance for your site. If you are not doing this then stop everything and read this. Hopefully you will be convinced. I for one use it all the time.

How do we do it in Django? [...]

Enable GZip Compression in Django is a post from: Therefore Systems

]]> GZip compression reduces size of payload sent to browser which in turn increases performance for your site. If you are not doing this then stop everything and read this. Hopefully you will be convinced. I for one use it all the time.

How do we do it in Django? Just include GZip Middleware. How? Easy. In your settings.py file look for MIDDLEWARE_CLASSES and add

django.middleware.gzip.GZipMiddleware

Here it is in my settings.py along with other middleware classes I am using.

MIDDLEWARE_CLASSES = (
    'django.middleware.common.CommonMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.gzip.GZipMiddleware',

)

I created a test page with lots of lorem ipsum and look at the difference in size of data transferred to the browser.

Without GZip.

Django GZip compression

With GZip.

Django GZip compression

 

Of course there are many other steps you can and you must take to improve performance of your site. Here is the link again to the site which you must read if you care about performance.

Enable GZip Compression in Django is a post from: Therefore Systems

]]> http://www.thereforesystems.com/enable-gzip-compression-in-django/feed/ 0 http://www.thereforesystems.com/enable-gzip-compression-in-django/http://feedproxy.google.com/~r/ThereforeSystems/~3/xUGYZh591H8/ Customize Response Headers in Django http://feedproxy.google.com/~r/OneDotNetWay/~3/I4GyCitfYR0/ http://www.thereforesystems.com/customize-response-headers-in-django/#comments Mon, 26 Mar 2012 00:32:39 +0000 Deepak http://www.thereforesystems.com/?p=1180 Django makes it as easy as it can be to work with Response Headers. These headers in case you did not know are sent to the browser along with the response to a request. You can customize values for existing headers and also add new headers. In this example we will look at how easily [...]

Customize Response Headers in Django is a post from: Therefore Systems

]]> Django makes it as easy as it can be to work with Response Headers. These headers in case you did not know are sent to the browser along with the response to a request. You can customize values for existing headers and also add new headers. In this example we will look at how easily it is done in Django.

We will use a simple example of a page which displays current server date and time. The output of the page does not matter for this example because we are focusing on Response Headers here. Our example page is served by this view:

def current_datetime(request):
    now = datetime.datetime.now()
    t = get_template('current_datetime.html')
    c = Context({'current_date': now})
    r = HttpResponse(t.render(c))
    return r

 

By default Django will send Content-Type, Date and Server response headers to the browser as seen in the screenshot below.

Default Response Headers from Django

Let’s say that we want to modify the value for Server header. You know, to feel the false satisfaction of making it hard for hackers to find out the technology stack used by our website. Besides the sarcasm, it can be done by modifying our view like this:

def current_datetime(request):
    now = datetime.datetime.now()
    t = get_template('current_datetime.html')
    c = Context({'current_date': now})
    r = HttpResponse(t.render(c))
    r['Server'] = 'Served by 3cpo'
    return r

 

Each view in Django returns a HttpResponse and we can work with it as we would work with a dictionary. We can see that the value for Server response header has been changed to ‘Served by 3cpo’.

Server Header Served by Django

Adding a new header is also simple. It is done by adding a new element to HttpResponse we send back. As shown here.

def current_datetime(request):
    now = datetime.datetime.now()
    t = get_template('current_datetime.html')
    c = Context({'current_date': now})
    r = HttpResponse(t.render(c))
    r['Server'] = 'Served by 3cpo'
    r['x-powered-by'] = 'my Linux server'
    return r

 

We have just included a new response header ‘x-powered-by’ which is set to ‘my Linux server’.

Adding new Response Header in Django

Simple enough, right? Well, this is what I like about Django and its batteries included approach.

Customize Response Headers in Django is a post from: Therefore Systems

]]> http://www.thereforesystems.com/customize-response-headers-in-django/feed/ 1 http://www.thereforesystems.com/customize-response-headers-in-django/http://feedproxy.google.com/~r/ThereforeSystems/~3/ksdFeLKT5To/ Beautiful Python: Working With English Alphabets http://feedproxy.google.com/~r/OneDotNetWay/~3/y01KUFhc7Ac/ http://www.thereforesystems.com/beautiful-python-working-with-english-alphabets/#comments Tue, 20 Mar 2012 23:26:40 +0000 Deepak http://www.thereforesystems.com/?p=1174 Yesterday while working on my website I came across a need to display links which start with alphabets from A – Z. Now there are many ways to skin a cat and one of them is to create an array and fill it with 26 elements, each representing an alphabet. Something like a[0] = ‘A’, [...]

Beautiful Python: Working With English Alphabets is a post from: Therefore Systems

]]> Yesterday while working on my website I came across a need to display links which start with alphabets from A – Z. Now there are many ways to skin a cat and one of them is to create an array and fill it with 26 elements, each representing an alphabet. Something like a[0] = ‘A’, a[1] = ‘B’ and so on. But that is not Pythonic. This is:

First step is to get all alphabets in English language

>>> import string
>>> alphas = string.ascii_lowercase
>>> alphas
‘abcdefghijklmnopqrstuvwxyz’
>>>

Great! But I’d like to have them as a list so that I produce links for each element or do something else with them.

>>> import string
>>> alphas = string.ascii_lowercase
>>> alphas
‘abcdefghijklmnopqrstuvwxyz’
>>> list_of_alphas = list(alphas)
>>> list_of_alphas
['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p',
'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']
>>>

This looks good. How about making them all upper case? Easy enough.

>>> import string
>>> alphas = string.swapcase(string.ascii_lowercase)
>>> list_of_alphas = list(alphas)
>>> list_of_alphas
['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z']
>>>

I think this is pretty cool.

Beautiful Python: Working With English Alphabets is a post from: Therefore Systems

]]> http://www.thereforesystems.com/beautiful-python-working-with-english-alphabets/feed/ 0 http://www.thereforesystems.com/beautiful-python-working-with-english-alphabets/http://feedproxy.google.com/~r/ThereforeSystems/~3/4PhlJBnOA2Y/ The Zen Of Python http://feedproxy.google.com/~r/OneDotNetWay/~3/tjkvcVzqTqs/ http://www.thereforesystems.com/the-zen-of-python/#comments Tue, 20 Mar 2012 00:14:36 +0000 Deepak http://www.thereforesystems.com/?p=1172 These days I am doing a great amount of work using Python. If you are game to learn a new language then I highly recommend looking at Python. You will find it both fun and productive. Basic tenets of the language can be summarized in what is called “The Zen of Python”.

The Zen [...]

The Zen Of Python is a post from: Therefore Systems

]]> These days I am doing a great amount of work using Python. If you are game to learn a new language then I highly recommend looking at Python. You will find it both fun and productive. Basic tenets of the language can be summarized in what is called “The Zen of Python”.

The Zen of Python, by Tim Peters

  • Beautiful is better than ugly.
  • Explicit is better than implicit.
  • Simple is better than complex.
  • Complex is better than complicated.
  • Flat is better than nested.
  • Sparse is better than dense.
  • Readability counts.
  • Special cases aren’t special enough to break the rules.
  • Although practicality beats purity.
  • Errors should never pass silently.
  • Unless explicitly silenced.
  • In the face of ambiguity, refuse the temptation to guess.
  • There should be one– and preferably only one –obvious way to do it.
  • Although that way may not be obvious at first unless you’re Dutch.
  • Now is better than never.
  • Although never is often better than *right* now.
  • If the implementation is hard to explain, it’s a bad idea.
  • If the implementation is easy to explain, it may be a good idea.
  • Namespaces are one honking great idea — let’s do more of those!

Where did I get this from? Well, from Python itself. Just type   import this  on Python prompt.

The Zen Of Python is a post from: Therefore Systems

]]> http://www.thereforesystems.com/the-zen-of-python/feed/ 0 http://www.thereforesystems.com/the-zen-of-python/http://feedproxy.google.com/~r/ThereforeSystems/~3/9juNxzdgpi8/ Install classic desktop in Ubuntu 11.10 http://feedproxy.google.com/~r/OneDotNetWay/~3/WW4Alq-dd00/ http://www.thereforesystems.com/install-classic-gnome-desktop-in-ubuntu-11-10/#comments Mon, 12 Mar 2012 06:07:25 +0000 Deepak http://www.thereforesystems.com/?p=1165 Ubuntu 11.10 does not include classic GNOME desktop by default. And if you are like me then you want to get rid of Unity as soon as you log on. GNOME desktop can be installed by executing this command in terminal.

sudo apt-get install gnome-panel

After the package is installed, log out and log back [...]

Install classic desktop in Ubuntu 11.10 is a post from: Therefore Systems

]]> Ubuntu 11.10 does not include classic GNOME desktop by default. And if you are like me then you want to get rid of Unity as soon as you log on. GNOME desktop can be installed by executing this command in terminal.

sudo apt-get install gnome-panel

After the package is installed, log out and log back in. Click on the gear icon and select GNOME Classic or GNOME Classic (No effects) as per liking. That’s it. Classic desktop should be back now and life will seem a bit more normal.

Ubuntu Log in screen

Install classic desktop in Ubuntu 11.10 is a post from: Therefore Systems

]]> http://www.thereforesystems.com/install-classic-gnome-desktop-in-ubuntu-11-10/feed/ 0 http://www.thereforesystems.com/install-classic-gnome-desktop-in-ubuntu-11-10/http://feedproxy.google.com/~r/ThereforeSystems/~3/nTnGVTxqmRs/ WAT080: Failed to locate the Windows Azure SDK. Please make sure the Windows Azure SDK v1.5 is installed. http://feedproxy.google.com/~r/OneDotNetWay/~3/X3hU_OylSK0/ http://www.thereforesystems.com/wat080-failed-to-locate-the-windows-azure-sdk-please-make-sure-the-windows-azure-sdk-v1-5-is-installed/#comments Tue, 07 Feb 2012 10:32:50 +0000 Deepak http://www.thereforesystems.com/?p=1153 After installing Windows Azure SDK and Visual Studio tools November 2011, I got this error when compiling an existing Cloud project.

WAT080: Failed to locate the Windows Azure SDK. Please make sure the Windows Azure SDK v1.5 is installed.

This post documents the roller coaster ride I went through to solve the problem. If you [...]

WAT080: Failed to locate the Windows Azure SDK. Please make sure the Windows Azure SDK v1.5 is installed. is a post from: Therefore Systems

]]> After installing Windows Azure SDK and Visual Studio tools November 2011, I got this error when compiling an existing Cloud project.

WAT080: Failed to locate the Windows Azure SDK. Please make sure the Windows Azure SDK v1.5 is installed.

This post documents the roller coaster ride I went through to solve the problem. If you are interested in just the solution then here it is:

Download the bits from this page and install them manually.

If you are interested in how I got to the solution then read on.

Before anything, let me clarify that I already had an older version of Azure SDK and tools on my machine. I used Web Platform installer to install the latest Azure SDK and Visual Studio Tools i.e. November update. Then a drama started.

The build error I got said that I should make sure that Windows Azure SDK v1.5 is installed. But I already installed v1.6. If the project files were changed between versions of tools then they should have been upgraded to latest version by Visual Studio. This did not happen. My first maneuver was to re-install Visual Studio tools. I downloaded just the standalone installer for tools and tried installing it. I got this error.

 image

The log file showed me these errors:

[16AC:16B0][2012-02-07T07:21:21]: Error 0×80070643: Failed to install MSI package.
[16AC:16B0][2012-02-07T07:21:21]: Error 0×80070643: Failed to execute MSI package.
[1744:1748][2012-02-07T07:21:21]: Error 0×80070643: Failed to configure per-machine MSI package.
[1744:1748][2012-02-07T07:21:21]: Error 0×80070643: Failed to execute MSI package.

 

I was in no mood for looking into the details of errors in the log file. I just wanted to get going with Azure and not worry about installer logs. So I uninstalled the SDK, Authoring Tools and Visual Studio tools to get a clean Azure free environment.

image

After uninstalling Azure bits I fired up Web Platform Installer and installed Azure SDK and tools. Little did I know that this was not going to work. Here is a screenshot of the errors I got.

image

By this time I was annoyed (you may substitute “annoyed” with a more colorful word of your choice). Web Platform Installer should just do it, right? It should take care of dependencies, right? Well that was not the case.

By this time I gave up on Web Platform Installer and downloaded standalone Azure bits and decided to install them manually. Here is the download link:

http://www.microsoft.com/download/en/details.aspx?displaylang=en&id=28045

I downloaded and installed the ones highlighted below.

image

After installing Azure Emulator, Libs and SDK, I installed Visual Studio Tools and it installed correctly.

image

I opened the project which was giving me a build error. Visual Studio asked me to convert it to a newer format. I happily obliged. Finally I saw Build Succeeded.

Although not a big deal specially after the issue was resolved, I still feel that installer could have done a better job. Anyhow, I’m back in the cloud Smile

WAT080: Failed to locate the Windows Azure SDK. Please make sure the Windows Azure SDK v1.5 is installed. is a post from: Therefore Systems

]]> http://www.thereforesystems.com/wat080-failed-to-locate-the-windows-azure-sdk-please-make-sure-the-windows-azure-sdk-v1-5-is-installed/feed/ 3 http://www.thereforesystems.com/wat080-failed-to-locate-the-windows-azure-sdk-please-make-sure-the-windows-azure-sdk-v1-5-is-installed/http://feedproxy.google.com/~r/ThereforeSystems/~3/oFmV92Za4oY/ Remove langauge resources and clean up disk space on mac http://feedproxy.google.com/~r/OneDotNetWay/~3/bE_fB5SgU_8/ http://www.thereforesystems.com/remove-langauge-resources-and-clean-up-disk-space-on-mac/#comments Sat, 04 Feb 2012 12:10:06 +0000 Deepak http://www.thereforesystems.com/?p=1135 Since last few days I noticed a significant decline in performance on my mac. After opening about 8 different apps my machine would become irritatingly unresponsive. Now macs don’t slow down, or do they? Well the fact is that they do and this could be because of a number of reasons. In my case it [...]

Remove langauge resources and clean up disk space on mac is a post from: Therefore Systems

]]> Since last few days I noticed a significant decline in performance on my mac. After opening about 8 different apps my machine would become irritatingly unresponsive. Now macs don’t slow down, or do they? Well the fact is that they do and this could be because of a number of reasons. In my case it was due to lack of empty space on my hard drive. So it was time for a clean up. I started by deleting music files which I would never listen to. Then I started thinking about other stuff I can do without and which comes with Mac OSX pre-installed. Language files happened to be one such culprit. In reality I don’t use anything other than English on my machine. Maybe once in a while I read stuff in hindi but that’s about it.

To clean up unnecessary language resources I found a utility called Monolingual. It removes files for languages you do not need. After running the utility, I gained 2.1GB of disk space.

Screen Shot 2012-02-04 at 11.08.29 PM.png

Download Monolingual.

Remove langauge resources and clean up disk space on mac is a post from: Therefore Systems

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