Computer Science Notes

Installing Android SDK offline.

2011-06-10T11:22:00.000-04:00

Hi,

I was searching for a way to install android SDK on offline. I need this if the bandwidth is limited or so.

Luckily I found Quakeboy's post on How to install Android SDK without internet connection?, it was excellent.

Here is how to do it:

1-Make sure that you have JDK installed and eclipse (Helios or Galileo) as well.

2- Download and install the SDK Manager from here.

3- Using the repositories (SDK Repository, Add-Ons, KYOCERA, LG, Sony Ericsson, and Samsung) download the files you need in the way Quakeboy illustrated:

remove the xml file, then add the file name you need from the <sdk:url> section

For example, the Samsung add-on:

the repository url is:

http://innovator.samsungmobile.com/android/repository/repository.xml

the file is <sdk:url>addon_samsung_GT_2.2_api-8_r01.zip</sdk:url>

then the link should be

http://innovator.samsungmobile.com/android/repository/addon_samsung_GT_2.2_api-8_r01.zip

Please note that some repositories put the complete url like Sony Ericsson.

4- Move to the android folder in the Program Files, then to the android-sdk folder

5- Create the following directories: "add-ons", "docs", "extras", "platform-tools", "samples"

6- Extract the files inside the parent directory of each of the following zip file to its coresponding directory and rename it to be like the pictures:

The first folder (kyocera) is the only one that will not be renamed.

Make sure that doc is the parent directory.

This is the extra folder

The platforms folder, the last folder is the only one that should be renamed.

platform tools

samples

After that, run eclipse, and from Help menu, choose Install new Software. Then click Add, then Archive, then choose the file ADT-11.0.0.zip
After installation, go to preferences then android tab. then put the path to android SDK in the SDK Location field.

Now the SDK is ready(^_^)

About the installation, there is an easier way to install the SDK. I did test it with some files.
To do it, create a folder named "temp" in the sdk-android folder, then put a copy of all files that you downloaded in the folder. Run the SDK Manager, it should test the files in the temp and the connection. Mark the packages you want and proceed with installation. The SDK Manager should use your files instead of downloading it from Internet.

Avoiding ARP Attacks

2011-04-28T13:48:00.000-04:00

Hi,

Did you experienced "ARP Spoofing" before?
One of my network members use it to cut the internet on other members so that he can download faster! To cut the internet, he used a program called netcut. I will not give the link here, but if you wanted to try it, google it.
The netcut program uses the the ARP Spoofing. The previous article discuses what is it and how it works and defenses if you wanted to know more details.

To avoid it, you can install comodo firewall (there is a free version), or any other firewall that has ARP Poisoning detection feature. And make sure of enabling it.
You can also use one of the programs mentioned in the wikipedia article.

Another solution is to use static ARP association for the gateway in the ARP Cache (And for all network members if the network is small and uses static IP addresses).

How to do it on Windows?
First, you should know the IP and MAC address of your gateway.
open the command prompt (with administrative privileges)
on windows XP, use this command:
arp -d "the ip of your gateway, without the quotes"
then
arp -s "the ip of your gateway" "the MAC address of your gateway"
On Windows 7, use this command:

netsh interface ip delete neighbors "Local Area Connection (or the connection name if you have different name)" "the ip of your gateway"
then
netsh interface ip add neighbors "Local Area Connection(or the connection name)" "the ip of your gateway" "the MAC address of your gateway"

To make sure that it is done, use this command to show the table

arp -a

You must do this every time you start your PC.

You can put these commands in a batch file and run it every time the Windows starts.

Write Binary file from Oracle Forms 6i

2011-04-27T08:23:00.001-04:00

Hi,

Last month, I had a problem; I was asked to add a functionality to download file(s) stored in a BLOB column in an Oracle database to the client machine using Oracle Forms 6i. The BLOB contents are uploaded using a web application. The file may be a pdf, image, word document, sheet, ...etc. I should not use any external tools that have to be installed on the client beside the Forms 6i runtime.

I searched in the internet for a long time, until I found an article for the CLOB. After reading and casting the BLOB data, I used the idea from the third comment (3.Matt Jernigan's), but it didn't work properly with TEXT_IO package because the PUT function is only implemented for text mode. One of the problems is adding a chr(13) automatically after chr(10), and so on for all other control characters ending with a corrupted file.

I decided to use Windows APIs functions to write the binary file (because of a friend advice). I used "CreateFile", "WriteFile", and "CloseHandle". And it worked!

For more information about how to do this, here is how to interface with C functions from Forms 6i. And the three functions documentation are as following:"CreateFile", "WriteFile", and "CloseHandle". The library you should include is "Kernel32.dll".

Browsers Performance 3/3

2010-09-06T13:37:00.034-04:00

I made a graph for the four Browsers Comparison made in the last post

and this is for the Total Score

Results shows that MSIE is really too slow when comparing with any of the other three browsers

Microsoft must do hard work to compete with other web browsers.

Also, I think Google Chrome's First Goal is Performance :), I'm not in the company, but it seems they did Excellent work to make their web browser reaches this performance.

Please note that the above detailed score varies according to many things as Operating System, Processor, Memory, and browser version. but if you made a test, the final results will be near mine I think.

I think this performance will encourage decision maker to make the old web applications compatible with Google Chrome or Safari to enhance it's performance.

Have a nice day!

Browsers Performance 2/3

2010-09-05T17:51:00.003-04:00

Today I tested both Google Chrome 6.0.472.53 and Firefox 3.6.8 using the same link in yesterday's post.
Here are the results on my PC:
Chrome:
1091.92 runs/s (Total)
and
Firefox
446.65 runs/s (Total)
as you can see, most results are in Chrome side! Although Firefox significantly beats Chrome in some tests such as MD5 Hashing and Spectral Norm of a Matrix!
You can use the same site to show the Comparison between the Two Browsers
next time I'll put a comparison for the four Browsers!

Enjoy your self!

Browsers Performance 1/3

2010-09-05T01:37:00.016-04:00

I have some old web applications, one day I opened it using firefox, and I thought it is faster than IE!
I was searching for a tool to give good measure of the performance.

Today, I found a tool to test web browsers performance by Mozilla called Dromaeo
Although there are some notes about it from web browsers' vendors as you can see in the previous link, I decided to test the most common 4 browsers using it.

Today I tested two browsers, IE8 and Safari 5.0.1 on Windows 7 Ultimate, Machine 4 Gig ram and Core2 due processor 2.53

In this test, all the sub tests are used except Base 64 Encoding and Decoding and Dom Query because they didn't run on IE8

To run the tests on your machine use this link from your browser.

Please try to close all your programs but the explorer and disable IE's JavaScript response notification message.

the test takes about half an hour

Here are the results on my PC:

IE8

125.27 runs/s (Total)

and

Safari

855.79 runs/s (Total)

as you can see, there is a significant gap between the performance of the two browsers, either in the total, and in most of the sub tests!
tomorrow, I'll test Google Chrome, and Firefox.

Enjoy your time!

Hello World!

2010-09-04T19:14:00.000-04:00

I created this blog to share many interesting things I care about from magazines, books, websites,... etc. Those things are related to to my field of study (Computer Science). So, I may be talking about new Techs, tips or tricks in a Programming Language or a Software, Software Comparison, or any idea that is related to CS

I'll be very happy if you made use of anything from here :)

Have a nice day!