1. Presented by :Dr Srinivasa Gowda GK BE,Mtech,PhD, Post Doctorate ACS College of Engineering, Bangalore

2. To introduce the concept of server-side development and to explore the role of a web server in handling client requests. to take a quick tour of PHP, a powerful server- side scripting language, and to discuss program control and functions. Objectives

3. I will explore the fundamental concepts of server-side development and learn how to use PHP, a popular server-side scripting language, to build dynamic and interactive web applications. Introduction to Server-Side Development with PHP

4. Server-side development involves creating web applications that run on a server and generate dynamic content for clients. PHP is a popular server-side scripting language used for web development. PHP allows you to embed server-side logic within HTML to create dynamic and interactive web pages.

5. A web server is responsible for receiving client requests, processing them, and sending back HTTP responses containing the requested content. Server-side development involves interacting with databases, handling user authentication, and implementing security measures.

6. PHP provides program control constructs such as if statements, switch statements, and loops to make decisions and repeat actions based on conditions. Functions in PHP allow you to organize code into reusable blocks and perform specific tasks.

7. PHP has a wide range of built-in functions that can be used for various purposes. You can define your own functions in PHP to suit the specific needs of your web application. Understanding the fundamental concepts of server-side development and PHP will enable you to build dynamic and feature- rich web applications.

8. What is Server-Side Development? Server-Side Development refers to the process of creating web applications that run on a server and generate dynamic content to be sent to the client's web browser. Unlike client-side development, which focuses on the user interface and functionality within the browser, server-side development deals with processing requests, interacting with databases, and generating responses to be displayed in the browser.

9. What is Server-Side Development? Receiving client requests: The web server receives HTTP requests from clients, typically web browsers, which are sent when a user accesses a web page or performs an action on the website.

10. What is Server-Side Development? Handling routing and URL mapping: The server examines the request to determine which web page or functionality the client is requesting. This process is often based on URL routing and mapping rules defined in the server configuration.

11. What is Server-Side Development? Processing the request: Once the server identifies the requested web page or functionality, it processes the request. This may involve retrieving data from databases, interacting with external APIs, or performing other computations to generate the dynamic content.

12. What is Server-Side Development? Generating the response: After processing the request and executing the necessary server-side scripts, the server generates a response containing the dynamically generated content. The response typically includes HTML, CSS, JavaScript, and other resources needed to render the web page correctly.

13. What is Server-Side Development? Sending the response to the client: The server sends the generated response back to the client's web browser using the HTTP protocol. The client's browser then interprets the response and renders the web page accordingly. Client-side rendering: Once the client receives the response, any client-side scripts (JavaScript) embedded within the web page can execute to add interactivity and manipulate the content on the client-side. Displaying the web page: Finally, the client's web browser displays the web page with the dynamically generated content and any client-side interactivity added through JavaScript.

14. A Web Server's Responsibilities A web server plays a crucial role in server-side development. It receives HTTP requests from clients (usually web browsers), processes those requests, and sends back HTTP responses containing the requested content. The web server is responsible for hosting web applications, managing security, handling user authentication, and facilitating communication between the client and the server-side scripts.

15. A Web Server's Responsibilities Receiving and handling HTTP requests: The web server is responsible for receiving incoming HTTP requests from clients, usually web browsers. It listens for requests on a specific port (usually port 80 for HTTP) and handles them appropriately. Serving static files: The web server is responsible for delivering static files, such as HTML, CSS, JavaScript, images, and other resources, to the client's web browser. It retrieves these files from the appropriate location on the server's file system and sends them as HTTP responses.

16. A Web Server's Responsibilities Executing server-side scripts: In addition to serving static files, the web server executes server-side scripts, such as PHP files, when requested by clients. It passes the request to the appropriate server-side scripting engine, which processes the script and generates dynamic content to be sent back as the HTTP response. Managing security: Web servers play a critical role in ensuring the security of web applications. They enforce security measures such as SSL/TLS encryption for secure data transmission, authentication mechanisms to verify the identity of clients, and access control mechanisms to protect sensitive resources from unauthorized access.

17. A Web Server's Responsibilities Handling URL routing and mapping: The web server routes incoming requests to the appropriate destination within the web application. It uses URL routing and mapping rules to determine which script or handler should process the request based on the requested URL. Managing sessions and cookies: Web servers often handle session management by generating unique session identifiers for clients and maintaining session data. They also handle the storage and retrieval of cookies, which are small pieces of data sent by the server to the client's browser and then returned with subsequent requests.

18. A Web Server's Responsibilities Caching and performance optimization: Web servers can implement caching mechanisms to improve performance by storing static or frequently accessed content in memory or on disk. This reduces the need to regenerate the content for each request, resulting in faster response times. Logging and monitoring: Web servers maintain logs of incoming requests, error messages, and other relevant information. These logs can be used for troubleshooting, performance analysis, and security auditing purposes. Web servers may also provide monitoring tools to track server performance, resource usage, and traffic patterns. Overall, a web server plays a crucial role in serving web applications, managing security, handling dynamic content generation, and ensuring reliable and efficient communication between clients and the server-side scripts or resources.

19. Quick Tour of PHP PHP (Hypertext Preprocessor) is a widely-used server-side scripting language designed specifically for web development. It is known for its ease of use, flexibility, and powerful features. PHP code is embedded within HTML, allowing you to mix dynamic server-side logic with static client-side content. To get started with PHP, you need access to a web server with PHP support installed. PHP files have a.php extension and can be executed on the server when requested by a client.

20. Syntax: PHP code is embedded within HTML and is enclosed in special tags:. This allows you to mix PHP code with HTML markup, making it easy to generate dynamic content within web pages. Variables: In PHP, you can declare variables to store data. Variables in PHP start with a dollar sign ($) followed by the variable name. PHP variables are loosely typed, meaning you don't need to specify the data type explicitly. Quick Tour of PHP Data Types: PHP supports various data types, including strings, integers, floats, booleans, arrays, and more. PHP also provides type casting functions to convert values between different data types. Control Structures: PHP offers control structures like if statements, switch statements, and loops (such as for, while, and foreach) to control the flow of execution based on conditions or iterate over data. Quick Tour of PHP

21. Functions: PHP allows you to define and use functions to encapsulate reusable blocks of code. Functions can accept parameters and return values, providing modularity and code organization. Arrays: PHP provides powerful array handling capabilities. You can create indexed arrays, associative arrays, or multidimensional arrays to store and manipulate collections of data. Quick Tour of PHP Database Connectivity: PHP has built-in functions and extensions for connecting to various databases like MySQL, PostgreSQL, and SQLite. This enables you to perform database operations and interact with data seamlessly. Error Handling: PHP offers error reporting and handling mechanisms. You can set error reporting levels, handle errors gracefully, and log error messages for debugging purposes. Quick Tour of PHP

22. File Handling: PHP provides functions to read, write, and manipulate files on the server's file system. You can open files, read data, write data, and perform various file operations using PHP's file handling functions. Libraries and Frameworks: PHP has a vast ecosystem of libraries and frameworks that provide pre-built functionalities and accelerate web development. Popular PHP frameworks include Laravel, Symfony, and CodeIgniter. Quick Tour of PHP This quick tour gives you a glimpse into the core features and concepts of PHP. With these fundamentals, you can start exploring PHP further and leverage its power to create dynamic and interactive web applications Quick Tour of PHP

23. Program Control PHP provides various constructs for program control, allowing you to make decisions and repeat actions based on certain conditions. These include if statements, switch statements, loops (such as for, while, and foreach), and more. With program control, you can create intelligent and dynamic behavior in your web applications.

24. Program control in PHP allows you to make decisions, repeat actions based on conditions, and control the flow of execution in your code. Here are some key constructs for program control in PHP:

25. 1.If Statements: If statements allow you to execute a block of code based on a specified condition. You can use the if statement alone or combine it with else and elseif statements to handle multiple conditions. For example: if (condition) { // Code to execute if the condition is true } elseif (another condition) { // Code to execute if the previous condition is false and this condition is true } else { // Code to execute if none of the conditions are true }

26. 2.Switch Statements: Switch statements provide an alternative way to handle multiple conditions. It allows you to test a variable against multiple possible values and execute different blocks of code based on the matching value. For example: switch ($variable) { case value1: // Code to execute if $variable matches value1 break; case value2: // Code to execute if $variable matches value2 break; default: // Code to execute if $variable doesn't match any cases }

27. 3.Loops: Loops in PHP allow you to repeat a block of code multiple times based on a specified condition. There are several types of loops available: for loop: Executes a block of code for a specified number of iterations. while loop: Executes a block of code as long as a condition is true. do-while loop: Executes a block of code at least once, and then repeats as long as a condition is true. foreach loop: Iterates over elements in an array or collection. Here's an example of a for loop in PHP: for ($i = 0; $i < 5; $i++) { // Code to execute for each iteration }

28. 4.Break and Continue: The break statement allows you to exit a loop prematurely, stopping further iterations. The continue statement allows you to skip the current iteration and move to the next one. These statements are typically used within loops to control the flow of execution based on certain conditions. Program control constructs are essential for creating dynamic and intelligent behavior in your PHP code. They allow you to handle different scenarios, make decisions, and repeat actions as needed, enhancing the functionality and interactivity of your web applications.

29. Program control in PHP allows you to make decisions, repeat actions based on conditions, and control the flow of execution in your code. Here are some key constructs for program control in PHP: If Statements: If statements allow you to execute a block of code based on a specified condition. You can use the if statement alone or combine it with else and elseif statements to handle multiple conditions. For example: php Copy code if (condition) { // Code to execute if the condition is true } elseif (another condition) { // Code to execute if the previous condition is false and this condition is true } else { // Code to execute if none of the conditions are true } Switch Statements: Switch statements provide an alternative way to handle multiple conditions. It allows you to test a variable against multiple possible values and execute different blocks of code based on the matching value. For example: php Copy code switch ($variable) { case value1: // Code to execute if $variable matches value1 break; case value2: // Code to execute if $variable matches value2 break; default: // Code to execute if $variable doesn't match any cases } Loops: Loops in PHP allow you to repeat a block of code multiple times based on a specified condition. There are several types of loops available: for loop: Executes a block of code for a specified number of iterations. while loop: Executes a block of code as long as a condition is true. do-while loop: Executes a block of code at least once, and then repeats as long as a condition is true. foreach loop: Iterates over elements in an array or collection. Here's an example of a for loop in PHP: php Copy code for ($i = 0; $i < 5; $i++) { // Code to execute for each iteration } Break and Continue: The break statement allows you to exit a loop prematurely, stopping further iterations. The continue statement allows you to skip the current iteration and move to the next one. These statements are typically used within loops to control the flow of execution based on certain conditions. Program control constructs are essential for creating dynamic and intelligent behavior in your PHP code. They allow you to handle different scenarios, make decisions, and repeat actions as needed, enhancing the functionality and interactivity of your web applications.

30. Functions Functions in PHP are reusable blocks of code that perform specific tasks. They allow you to organize your code into smaller, more manageable chunks and make it easier to maintain and reuse. Functions can accept parameters, perform operations, and return values. PHP provides built-in functions, and you can also define your own functions to suit your application's needs.

31. Functions in PHP allow you to encapsulate reusable blocks of code and perform specific tasks. They provide modularity and code organization, making it easier to maintain and reuse code. Here are some key aspects of functions in PHP:

32. Defining Functions: You can define your own functions in PHP using the function keyword, followed by the function name, a set of parentheses for parameters (if any), and curly braces to enclose the function body. Here's an example of a function definition: function greet($name) { echo "Hello, $name!"; }

33. 2.Calling Functions: Once a function is defined, you can call it by using its name followed by parentheses. If the function accepts parameters, you can pass values within the parentheses. Here's an example of calling the greet function defined above: greet("John");

34. 3.Function Parameters: Functions can accept parameters, which are variables that hold values passed to the function during the function call. You can define parameters in the function declaration within the parentheses. Parameters can have default values, making them optional. Here's an example: function add($num1, $num2 = 0) { return $num1 + $num2; } $result = add(5, 3); // Returns 8

35. 4.Return Values: Functions can return values using the return statement. The returned value can be assigned to a variable or used directly. If a function doesn't explicitly return a value, it returns NULL by default. Here's an example: function multiply($num1, $num2) { return $num1 * $num2; } $product = multiply(4, 2); // Returns 8

36. 3.Function Parameters: Functions can accept parameters, which are variables that hold values passed to the function during the function call. You can define parameters in the function declaration within the parentheses. Parameters can have default values, making them optional. Here's an example: function add($num1, $num2 = 0) { return $num1 + $num2; } $result = add(5, 3); // Returns 8

37. 5.Function Scope: Variables defined inside a function have local scope, which means they are accessible only within that function. Variables defined outside functions have global scope and can be accessed from anywhere in the PHP script. It's generally considered good practice to minimize the use of global variables and prefer passing values through function parameters and returning results.

38. 5.Built-in Functions: PHP provides a wide range of built-in functions that perform common tasks, such as manipulating strings, working with arrays, handling dates and times, and interacting with databases. These functions save development time by providing pre-defined functionality that you can use directly in your code.

39. By utilizing functions effectively, you can break down your code into smaller, more manageable units, promote reusability, and improve the overall structure and readability of your PHP programs.

40. Conclusion In this tutorial, we introduced the concept of server-side development and explored the role of a web server in handling client requests. We also took a quick tour of PHP, a powerful server-side scripting language, and discussed program control and functions. Armed with this knowledge, you are now ready to dive deeper into server-side development with PHP and build dynamic web applications.