Category Archives: Web Application Development

Web Application Development

How to Select a .NET Framework

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Motivation:

You need to select a .NET framework for your new project or for upgrading a legacy system.

However there are too many .NET framework branches so you are not sure which one is suitable with your need.

Guidelines:

You need to review the history of .NET framework and the differences among the various branches that include .NET Framework, ASP.NET Web Forms, ASP.NET MVC, .NET Core and .NET 6.

1. .NET Framework

The main purpose of .NET Framework is for building Windows Forms Applications.

  • .NET Framework 1.0 was released in 2002.
  • .NET Framework 2.0 was released in 2005.
  • .NET Framework 3.0 was released in 2006.
  • .NET Framework 3.5 was released in 2007.
  • .NET Framework 4.0 was released in 2010.
  • .NET Framework 4.5.2 was released in 2014.
  • .NET Framework 4.8 (the latest version) was released in 2019.
2. ASP.NET Web Forms

ASP.NET Web Forms was built on top of .NET Framework.

The main purpose of ASP.NET Web Forms is for building ASP.NET Web Forms Applications (multiple page web applications).

3. ASP.NET MVC

ASP.NET Web Forms does not follow MVC architecture pattern. Therefore MS built ASP.NET MVC.

ASP.NET MVC was built on top of .NET.

ASP.NET MVC is open-source software, apart from the ASP.NET Web Forms, which is proprietary.

The main purpose of ASP.NET MVC is for building ASP.NET MVC Applications (multiple page web applications based on MVC architecture pattern).

  • ASP.NET MVC 1.0 was released in 2009 (It was built on top of .NET Framework 3.5).
  • ASP.NET MVC 2.0 was released in 2010 (It was built on top of .NET Framework 4.0).
  • ASP.NET MVC 5.2.8 (the latest version) was released in 2022 (It was built on top of .NET Framework 4.8).
4. .NET Core

.NET Framework does not run on Linux or Unix and is proprietary. Therefore MS built .NET Core.

.NET Core runs on Windows, Linux and Unix, and is open-source software.

  • .NET Core 1.0 was released in 2016.
  • .NET Core 3.1 was released in 2019.
  • .NET Core then was renamed to just .NET in 2020 and .NET 5 was released in 2020. The .NET 4 name was not used to avoid name collision with .NET Framework.
  • .NET 6 (the latest version) was released in 2021.

The main purpose of .NET Core or .NET is for building Windows Forms Applications, ASP.NET MVC Applications and Single Page Applications that run on Windows, Linux and Unix.

The ASP.NET Web Forms Application type was removed from .NET Core or .NET.

5. .NET 6

Currently (in 2022) MS supports 2 branches of .NET:

  • .NET Framework 4.8 (containing Windows Forms Applications, Web Forms Applications, and ASP.NET MVC Applications) and
  • .NET 6 (containing Windows Forms Applications, ASP.NET MVC Applications and Single Page Applications).

Both .NET Framework 4.8 and .NET 6 support building microservices.

6. Final thoughts

For a new system, you probably should use .NET 6.

For a legacy system, if you are using ASP.NET Web Forms then you may stick with .NET Framework 4.8. Otherwise you may upgrade your system to .NET 6.

 

 

 

 

Web Application Development

How to Fix IIS Express HTTPS Error

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Problem:

You have created an ASP.NET web application with HTTPS.

You ran the application on https://localhost:5001 and got the “ERR_CONNECTION_RESET” error.

Solution:

1. Open Command Prompt with admin rights.

2. Type and press Enter

cd "C:\Program Files (x86)\IIS Express"

3. Type and press Enter

IISExpressAdminCmd.exe setupsslUrl -url:https://localhost:5001/ -UseSelfSigned

Change 5001 in the command above to the port you’re trying to use.

 

Web Application Development

How to Fix a Hacked WordPress Website

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Problem:

When you visit your WordPress website you are randomly redirected to unwanted websites.

Verification:
  • Log in your website as an Administrator.
  • Go to Appearance >> Theme File Editor.
  • Click on the Theme Functions link on the right side.
  • Verify if malicious code was injected into the functions.php file. Example of malicious code: 
    <?php @ini_set('display_errors', '0'); 
error_reporting(0); 
global $zeeta;
  • Download the wp-config.php file to your machine via FTP or SSH.
  • Verify if malicious code was injected into the wp-config.php file. Example of malicious code: 
    include_once(ABSPATH . WPINC . '/header.php');
Solution:
  • Stop the website.
  • Download the whole website to your local machine. 
    cd /var/hosting/huybien.com
ls
sudo zip -r huybien.zip /var/hosting/huybien.com/html
Configuration:
  • Log in your website as an Administrator.
  • Change your Administrator’s password.
  • Change permissions for the html folder. 
    sudo chmod -R 777 /var/hosting/huybien.com/html
  • Remove all the unused plug-ins or themes.
  • Revert permissions for the html folder and set permissions for the wp-content folder. 
    sudo chmod -R 755 /var/hosting/huybien.com/html
sudo chmod -R 775 /var/hosting/huybien.com/html/wp-content
  • Install, activate and configure a CAPTCHA plug-in to protect Login Form, Registration Form, Lost Password Form, Reset Password Form and Comment Form if there is no one.
  • Disable insecure FTP access if there is one.
  • Install and activate the Simple History plugin to review access to your website. After 1 or 2 days, review the access information, and possibly block the malicious IP addresses using the Windows Firewall.
  • Install, activate and configure Cerber Security plug-in to automatically detect and block the malicious IP addresses.
  • Back up database. 
    cd /home/ubuntu
ls
mysqldump -u root -p -h localhost huybiencomwp > huybiencomwp.sql
  • Back up files. 
    cd /home/ubuntu
ls
sudo zip -r /home/ubuntu/huybien.zip /var/hosting/huybien.com/html
  • Download database and files backup.
  • Remove the backups. 
    sudo rm -rf /home/ubuntu/huybiencomwp.sql
sudo rm -rf /home/ubuntu/huybien.zip
ls

 

 

Web Application Development

How to Manually Install PHP 7.4 for Windows Server 2019

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Motivation:

You want to understand how PHP works with IIS.

You want to prepare a PHP or WordPress development environment in Windows.

You want to update PHP to any version to address compatibility or security issues in Windows.

You may use Microsoft Web Platform Installer to install PHP for IIS. However the tool may restrict you from using only the supported versions.

Solution:

  • Install CGI for IIS on Turn Windows features on or off > Internet Information Services > World Wide Web Services > Application Development Features > CGI.
  • Download VC15 x86 Non Thread Safe package here or under PHP 7.4 section from http://windows.php.net/download/
  • Extract the ZIP file to the C:\Program Files (x86)\php-7.4.9-nts-Win32-vc15-x86 folder.
  • Rename the php-.ini-development file to php.ini.
  • Open the php.ini file and add the following line at the end of the file.
extension=php_wincache.dll
  • Uncomment the following lines
fastcgi.impersonate = 1;

cgi.fix_pathinfo=1;
cgi.force_redirect = 1 (and change the value to 0, i.e. cgi.force_redirect = 0)

extension_dir = "C:\Program Files (x86)\php-7.4.9-nts-Win32-vc15-x86\ext"

extension=php_curl.dll
extension=php_fileinfo.dll
extension=php_mbstring.dll
extension=php_exif.dll
extension=php_mysqli.dll
extension=php_pdo_mysql.dll
extension=php_openssl.dll

error_log = "C:\Program Files (x86)\php-7.4.9-nts-Win32-vc15-x86\php_errors.log"

error_log = syslog
  • A sample php.ini file can be download here.
  • Add C:\Program Files (x86)\php-7.4.9-nts-Win32-vc15-x86 to System Path.
  • Download x86 package of WinCache 2.0 for PHP 7.4 here or from https://sourceforge.net/projects/wincache/.
  • Extract and copy the php_wincache.dll file to C:\Program Files (x86)\php-7.4.9-nts-Win32-vc15-x86\ext
    folder.
  • Open IIS, click on Server name, double click on Handler Mappings, click on Add Module Mapping, and enter below information
Request path = *.php
Module = FastCgiModule
Executable = "C:\Program Files (x86)\php-7.4.9-nts-Win32-vc15-x86\php-cgi.exe"
Name = PHP 7.4
Request Restrictions = File or folder
php --version
    • Create phpinfo.php file with below content in the root website folder.
    <?php 
phpinfo(); 
?>

     

    Operating Systems, Web Application Development

    How to move a WordPress instance from one server to another Linux server

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    Motivation:

    You want to move a WordPress instance from one server to another to consolidate your websites to reduce cost.

    Solution:

    Install and use below Duplicator plugin to achieve your goal.

    https://wordpress.org/plugins/duplicator/

    User guide: https://snapcreek.com/duplicator/docs/quick-start/

    If everything goes well for you then congratulation!

    Otherwise, please review below possible problems and corresponding solutions.

    Problem 1:

    You don’t have a website on the new server.

    Solution 1:

    1. Create a new virtual host in the /etc/httpd/conf/httpd.conf

    <VirtualHost *:80>
ServerName example.com
ServerAlias www.example.com
DocumentRoot "/var/www/www.example.com"
</VirtualHost>

    2. Set 775 permission for /var/www/www.example.com

    3. Restart httpd service

    sudo systemctl restart httpd
    Problem 2:

    You are using Amazon Linux 2 server.

    You are logged in as ec2-user.

    You use WinSCP to upload files and edit configuration files.

    You cannot modify /etc/httpd/conf/httpd.conf and /etc/php.ini.

    Solution 2:

    1 View permission settings for the file

    ls -ld /etc/httpd/conf/httpd.conf

    The result indicates that the file owner is root user and root group, not ec2-user.

    2. View groups of a user

    groups ec2-user

    The result indicates that the ec2-user does not belong to root group.

    3. Add a user to root group

    sudo usermod -a -G root ec2-user

    4. Grant Read-Write permission against a file to root group

    sudo chmod g+rwx /etc/httpd/conf/httpd.conf
sudo chmod g+rwx /etc/php.ini

    5. Logout and login to the server again.

    Problem 3:

    You are using Amazon Linux 2 server. The ZipArchive feature is missing.

    Solution 3:

    1. Execute below commands:

    sudo amazon-linux-extras install php7.2
sudo yum install php-pear php-devel gcc libzip-devel zlib-devel
sudo pecl install zip-1.13.5 # we must specify a slightly older version due due to compatibility

    2. Add “extension=zip.so” to /etc/php.ini

    3. Restart the server

    sudo reboot
    Problem 4:

    You don’t have a WordPress database on the new Linux server.

    Solution 4:

    Execute below MySQL commands:

    CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';
CREATE DATABASE `wp_database`;
GRANT ALL PRIVILEGES ON `wp_database`.* TO "username"@"localhost";
FLUSH PRIVILEGES;
    Problem 5:

    An database error occurs while restoring a website.

    Solution 5:

    1. Execute below commands to remove the website:

    sudo chown -R ec2-user:apache /var/www/example.com
sudo chmod 2775 /var/www/example.com && find /var/www/example.com -type d -exec sudo chmod 2775 {} \;
find /var/www/example.com -type f -exec sudo chmod 0664 {} \;
rm -r /var/www/example.com

    2. Upload the Duplicator files again, and restore the website again.

    Problem 6:

    No write access against /var/www/example.com is available for Duplicator.

    Solution 6:

    1. Execute below commands:

    sudo chown -R ec2-user:apache /var/www/example.com
sudo chmod 2775 /var/www/example.com && find /var/www/example.com -type d -exec sudo chmod 2775 {} \;
find /var/www/example.com -type f -exec sudo chmod 0664 {} \;

    2. Run http://example.com/installer.php again.

    Operating Systems, Web Application Development

    How to Set File Permissions for WordPress on IIS

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    Motivation:

    • You have a WordPress instance in Windows with IIS.
    • You upload a file. Its thumbnail is not shown in Media Library.
    • You change the file permission. Its thumbnail now is shown correctly in Media Library.
    • You upload another file and have to change the file permission manually again.
    • How can we make WordPress automatically set the correct permission for new uploaded files?

    Procedure:

    1. Ensure that the the Identity of Application pool that the website is running under is ApplicationPoolIdentity.
    2. Execute below commands as Administrator
    icacls "C:\inetpub\wwwroot\domain.com" /grant "IUSR":(OI)(CI)F /T 
icacls "C:\inetpub\wwwroot\domain.com" /grant "IIS_IUSRS":(OI)(CI)F /T

    3. Open IIS Manager, click on your website, click Authentication, click Anonymous Authentication (which should be the only one enabled), click Edit, select Application pool identity if it is not selected, click OK.

     

     

    Web Application Development

    How to Manually Install PHP 8.1 for Windows 10

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    Motivation:

    You want to understand how PHP works with IIS.

    You want to prepare a PHP or WordPress development environment in Windows.

    You want to update PHP to any version to address compatibility or security issues in Windows.

    You may use Microsoft Web Platform Installer to install PHP for IIS. However the tool may restrict you from using only the supported versions.

    Solution:

    • Install CGI for IIS on Turn Windows features on or off > Internet Information Services > World Wide Web Services > Application Development Features > CGI.
    • Download VS16 x64 Non Thread Safe package under PHP 8.1 section on https://windows.php.net/download/.
    • Extract the ZIP file to C:\Program Files\php-8.1.10-nts-Win32-vs16-x64 folder.
    • Download the cacert.pem file and move it to the C:\Program Files\php-8.1.10-nts-Win32-vs16-x64\extras\ssl folder.
    • Copy the php-.ini-development file to php.ini.
    • Open the php.ini file and uncomment the following lines
    fastcgi.impersonate = 1;

cgi.fix_pathinfo=1;
cgi.force_redirect = 1 (and change the value to 0, i.e. cgi.force_redirect = 0)

extension_dir = "C:\Program Files\php-8.1.10-nts-Win32-vs16-x64\ext"

extension=curl
extension=fileinfo
extension=gd
extension=gettext
extension=mbstring
extension=exif ; Must be after mbstring as it depends on it
extension=mysqli
extension=openssl
extension=pdo_mysql

error_log = "C:\Program Files\php-8.1.10-nts-Win32-vs16-x64\php_errors.log"

error_log = syslog

curl.cainfo = "C:\Program Files\php-8.1.10-nts-Win32-vs16-x64\extras\ssl\cacert.pem"

openssl.capath="C:\Program Files\php-8.1.10-nts-Win32-vs16-x64\extras\ssl\cacert.pem"
    • Add C:\Program Files\php-8.1.10-nts-Win32-vs16-x64 to SYSTEM PATH.
    • Restart your machine.
    • Open cmd and execute the command below to ensure that the PHP file can be found in the SYSTEM PATH.
    php --version
    • Open IIS, click on Server name, double click on Handler Mappings > Add Module Mapping with below information
    Request path = *.php
Module = FastCgiModule
Executable = "C:\Program Files\php-8.1.10-nts-Win32-vs16-x64\php-cgi.exe"
Name = PHP 8.1
Request Restrictions = File or folder
    • Create phpinfo.php file with below content in the root website folder.
    <?php 
phpinfo(); 
?>

     

     

    Web Application Development

    How to Use Let’s Encrypt

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    Motivation:

    Why use an SSL/TLS certificate to secure your website?

    – To protect your website users from man-in-the-middle attacks.

    – To ensure the integrity of the data being sent to your website.

    Why use Let’s Encrypt SSL/TLS certificate?

    – Because it is FREE.

    Tested environment:

    1. Windows Server 2016/IIS 10
    2. win-acme.v2.1.10.896.x64.pluggable
    3. Ubuntu 18.04
    4. certbot 0.27.0

    For Windows and IIS:

    1. Log in a Windows server.
    2. Download win-acme.v2.1.10.896.x64.pluggable here or from https://github.com/win-acme/win-acme/releases.
    3. Unzip the files to C:\inetpub\win-acme.v2.1.10.896.x64.pluggable.
    4. Open cmd.exe as Administrator and cd to C:\inetpub\win-acme.v2.1.10.896.x64.pluggable
    5. Type wacs.exe and press Enter
    6. Follow the instructions.
    7. Open Task Scheduler and ensure that a task with description “Check for renewal of ACME certificates.” has been created.
    8. Open Firewall port 443 if needed.
    9. Open the selected website using HTTPS protocol.
    10. Update emails to which notifications will be sent: Open wacs.exe, type O, then A, then y, and enter an email.
    11. Remove website from automatic renewal: 
      wacs.exe --list
// Copy the exact name between ": " and " - renewed" without quotes.
// Example: [IISBinding] huybien.com
wacs.exe --cancel --friendlyname "[IISBinding] huybien.com"

    Redirecting HTTP to HTTPS in IIS7:

    1. Install the Microsoft URL Rewrite Module if needed.
    2. Make sure Require SSL is NOT checked under SSL Settings for your website.
    3. Copy and paste the following code between the <rules> and </rules> tags in your web.config file in your website root directory.
    <rule name="HTTP to HTTPS redirect" stopProcessing="true">
  <match url="(.*)" />
    <conditions>
      <add input="{HTTPS}" pattern="off" ignoreCase="true" />
    </conditions>
  <action type="Redirect" redirectType="Found" url="https://{HTTP_HOST}/{R:1}" />
</rule>

    4. Open your site using HTTP protocol and ensure that you are redirected to the HTTPS site.

    Multiple SSL Certificates per IP Address

    1. You have to use Server 2012 IIS to support Server Name Indication (SNI) which allows you to bind multiple SSL certificates to a single IP Address.
    2. Please repeat the Procedure for each site, then go to the IIS site, Bindings and ensure that the check box Require Server Name Indication is selected and the corresponding SSL Certificate is selected.
    3. Please be noted that SNI does not work with Windows XP clients.

    For Ubuntu and nginx

    1. Login as root via SSH to a Ubuntu server.
    2. Execute 3 commands below.
    sudo apt install python-certbot-nginx
sudo certbot --nginx -d huybien.com -d www.huybien.com -d example.com -d www.example.com
sudo certbot renew --dry-run

    3. Remove a certificate:

    sudo certbot delete

    4. Update emails to which notifications will be sent:

    sudo certbot register --update-registration --email info@huybien.com

    5. Review Let’s Encrypt’s log file:

    sudo nano /var/log/letsencrypt/letsencrypt.log

    Press Ctrl+W, then enter a string to be found. Press Alt+W to find a next match.

     

     

    Software Engineering Curriculum, Web Application Development

    Topic 7 – Introduction to Web Application Development

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    Why do I need to learn about web application development?

    Desktop applications are very powerful and convenient but their development, deployment and maintenance are daunting.

    The reason is that the platform dependency makes it very expensive to create a desktop application working on different versions of different operating systems, such as Windows, Linux and Mac OSX.

    Deployment and updates of desktop application typically require high privileges access to a computer machine, causing a problem for companies requiring high security.

    Fortunately, you can overcome these limitations by creating a web application running on a browser. To create a web application you need to learn about web application development.

    What can I do after finishing learning web application development?

    You will be able to create web applications like The BBC News, The WordPress Blog or The White House Website.

    This is exactly what I want to learn! What should I do now?

    Web application development requires a lot of reading. You have to master networking concepts, HTML, CSS, JavaScript, a programming language and a database management system for web. Please read
    – this Semmy Purewal (2014). Learning Web App Development. O’Reilly Media book, and
    – this Jon Duckett (2011). HTML & CSS – Design and Build Websites. John Wiley & Sons book first to get familiar with web application development.

    After that please read
    – this Stephen Greig (2013). CSS3 – Pushing the Limits. John Wiley & Sons book and
    – this Anne Boehm and Zak Ruvalcaba (2018). Murach’s HTML5 and CSS3. Mike Murach and Associates book to learn in-depth about HTML and CSS.

    JavaScript is the language for web development because it is implemented in most of the web browsers.
    Please read
    – this David Flanagan (2020). JavaScript: The Definitive Guide. O’Reilly Media book, and
    – this Kyle Simpson (2015). You Don’t Know JS. O’Reilly Media book, and
    – this Jon Duckett (2014). JavaScript and JQuery. Interactive Front-End Web Development. John Wiley & Sons book to master it.
    Strong knowledge of JavaScript will ease your web development learning very much.

    Single page application is the default front-end choice for most of new web development projects.
    Please read
    – this Kirupa Chinnathambi (2018). Learning React. Addison-Wesley Professional book, and
    – this Alex Banks and Eve Porcello (2020). Learning React Modern Patterns for Developing React Apps. O’Reilly book to learn how to create a single page application (SPA).

    After that you will have 4 main options. You can choose one of them. We STRONGLY recommend that you choose only ONE option.

    You should NOT learn all of them at the beginning. You could save your time by digging into only one option. After mastering the selected technology, you will realize that all of them are very similar in the sense of use.

    One note is that although their concepts are similar to one another but it still takes us much time to learn how to apply an approach to real world web application.

    When developing a real world web application, you often use only one or two of these 4 approaches. If you cannot make your own selection then we recommend you
    – a combination of the first and second option, or
    – a combination of the first and third option, or
    – a combination of the first and fourth option.

    The first option is PHP world.  Please read
    – this Luke Welling and Laura Thomson (2016). PHP and MySQL Web Development. Addison-Wesley Professional book or
    – this Robin Nixon (2021). Learning PHP, MySQL & JavaScript. O’Reilly book.
    After that depending on your projects you may need to read the books below
    – Brad Williams et al. (2015). Professional WordPress: Design and Development. Wrox.

    The second option is ASP.NET.
    Please read
    – this Adam Freeman (2020). Pro ASP.NET Core 3: Develop Cloud-Ready Web Applications Using MVC, Blazor, and Razor Pages. Apress book and
    – this Andrew Lock (2021). ASP.NET Core in Action. Manning book.

    A complementary part for this option is ASP.NET Web Forms that is a technology that you need to master if you are maintaining a legacy project.
    Please read this Imar Spaanjaars (2014). Beginning ASP.NET 4.5.1 in C# and VB. Wrox book to learn about ASP.NET Web Forms.

    The third option is Java world.
    If you are not familiar with Java language then please read
    – this Cay S. Horstmann (2019). Core Java. Volume I – Fundamentals. Pearson book, and
    – this Cay S. Horstmann (2019). Core Java. Volume II – Advanced Features. Pearson book first.

    Then please read
    – this Tim Downey (2021). Guide to Web Development with Java – Understanding Website Creation. Springer book or
    – this Nicholas S. Williams (2014). Professional Java for Web Applications. John Wiley & Sons book.

    After that please read this Mark Heckler (2021). Spring Boot – Up and Running – Building Cloud Native Java and Kotlin Applications. O’Reilly Media book.

    The 4th option is Node.js world.
    Please read
    – this Jonathan Wexler (2019). Get Programming with Node.js. Manning Publications book, and
    – this Bruno Joseph D’mello et al. (2017). Web Development with MongoDB and Node. Packt Publishing book.

    There are also several other options that you may consider if you are required to learn them for a maintenance project.
    These options include
    – Ruby on Rails, please read this Michael Hartl (2020). The Ruby on Rails Tutorial. Addison-Wesley Professional book,
    – Flask, please read this Miguel Grinberg (2018). Flask Web Development: Developing Web Applications with Python. O’Reilly Media book, and
    – Django    .

    If you need to convert a web application from one platform to another or create a web application framework then please read
    – this Leon Shklar and Richard Rosen (2009). Web Application Architecture. John Wiley & Sons book, and
    – this Leonard Richardson and Mike Amundsen (2013). RESTful Web APIs. O’Reilly Media book.

    After finishing the books please click Topic 8 – Introduction to Mobile Application Development to continue.