What is PHP and what does the acronym stand for?
PHP (Hypertext Preprocessor) is a server-side scripting language designed specifically for web development. Originally, PHP stood for Personal Home Page, but it was later renamed to PHP: Hypertext Preprocessor.
What are the different data types in PHP?
PHP has eight primitive data types: Integer (int), Float/Double, String, Boolean, Array, Object, NULL, and Resource. As of PHP 7, two additional types were added: Object and Callable.
What is type casting in PHP and how is it performed?
Type casting is converting one data type to another. In PHP, it can be done using either casting operators (int), (string), (array), etc., or functions like intval(), strval(), settype(). PHP also performs automatic type conversion.
Explain the difference between == and === operators in PHP.
The == operator checks only for equality of values, while === checks for both equality of values and equality of types. For example, '1' == 1 returns true, but '1' === 1 returns false.
What are PHP superglobals?
Superglobals are built-in variables always available in all scopes. These include: $_GET, $_POST, $_SERVER, $_FILES, $_COOKIE, $_SESSION, $_REQUEST, $_ENV, and $GLOBALS.
What is the difference between include and require in PHP?
Both include and require are used to include files, but they handle errors differently. require produces a fatal error and halts execution if the file is not found, while include only produces a warning and continues execution.
Explain variable scope in PHP.
PHP has four variable scopes: local (inside functions), global (outside functions), static (retains value between function calls), and superglobal (accessible everywhere). The 'global' keyword or $GLOBALS array is used to access global variables inside functions.
What is the difference between GET and POST methods?
GET sends data through URL parameters, visible in browser history, and has length limitations. POST sends data through HTTP request body, not visible in URL, more secure, and can handle larger data. GET is idempotent while POST is not.
What are magic constants in PHP?
Magic constants are predefined constants that change based on where they are used. Examples include __LINE__, __FILE__, __DIR__, __FUNCTION__, __CLASS__, __METHOD__, __NAMESPACE__. Their values are determined by where they are used.
What is the purpose of the final keyword in PHP?
The final keyword prevents child classes from overriding a method or prevents a class from being inherited. When used with methods, it prevents method overriding, and when used with classes, it prevents class inheritance.
What are traits in PHP?
Traits are mechanisms for code reuse in single inheritance languages like PHP. They allow you to reuse sets of methods freely in several independent classes living in different class hierarchies. They address the limitations of single inheritance.
Explain the concept of type hinting in PHP.
Type hinting enforces specified data types for function parameters and return values. It can be used with arrays, objects, interfaces, and scalar types (in PHP 7+). It helps catch type-related errors early and improves code reliability.
What is autoloading in PHP?
Autoloading automatically loads PHP classes without explicitly using require or include statements. spl_autoload_register() is commonly used to register autoloader functions. PSR-4 is the modern standard for autoloading in PHP.
What are anonymous functions in PHP?
Anonymous functions, also known as closures, are functions without a name that can access variables from the outside scope. They are often used as callback functions and can be assigned to variables.
Explain the difference between echo and print in PHP.
echo and print both output strings, but echo can take multiple parameters and is marginally faster, while print can only take one parameter and returns a value (always 1). echo is a language construct, not a function.
What is the use of the yield keyword in PHP?
yield is used to implement generators, which provide a way to iterate over a set of data without keeping the entire set in memory. It's memory-efficient for large datasets as it generates values on-the-fly.
What are magic methods in PHP?
Magic methods are special methods that override PHP's default behavior when certain actions are performed on an object. Examples include __construct(), __destruct(), __get(), __set(), __isset(), __unset(), __call(), __toString().
Explain the difference between self and $this in PHP.
self refers to the current class and is used to access static members, while $this refers to the current object instance and is used to access non-static members. self is resolved at compile time, while $this is resolved at runtime.
What is namespace in PHP?
Namespaces are a way of encapsulating related classes, interfaces, functions, and constants to avoid name collisions. They provide better organization and reusability of code. They are declared using the namespace keyword.
What are the different types of arrays in PHP?
PHP supports three types of arrays: Indexed arrays (numeric keys), Associative arrays (named keys), and Multidimensional arrays (arrays containing other arrays). Arrays in PHP are actually ordered maps.
Explain the concept of late static binding in PHP.
Late static binding refers to a way of using static keyword to reference the class that was initially called at runtime rather than the class where the method is defined. It's implemented using the static keyword instead of self.
What is the difference between unset() and null?
unset() completely removes a variable from memory, while setting a variable to null keeps the variable but sets its value to nothing. isset() returns false for both null values and unset variables.
What are PHP generators and when should they be used?
Generators provide a way to implement simple iterators without the overhead of creating a class implementing Iterator interface. They're useful when working with large datasets or infinite sequences as they save memory.
What is the difference between abstract class and interface?
Abstract classes can have properties and implemented methods, while interfaces can only have method signatures. A class can implement multiple interfaces but can extend only one abstract class. Abstract classes provide a partial implementation.
What are variadic functions in PHP?
Variadic functions can accept a variable number of arguments using the ... operator. func_get_args() can also be used to get an array of all passed arguments. They provide flexibility in function parameter handling.
Explain the concept of constructor property promotion in PHP 8.
Constructor property promotion is a shorthand syntax that allows declaring and initializing class properties directly in the constructor parameter list. It reduces boilerplate code by combining property declaration and constructor parameter definition.
What is the difference between count() and sizeof() in PHP?
count() and sizeof() are identical functions and can be used interchangeably. Both return the number of elements in an array or properties in an object. sizeof() is an alias of count(), created for C/C++ programmers' familiarity.
What is the purpose of the callable type hint in PHP?
The callable type hint ensures that a function parameter can be called as a function. It accepts regular functions, object methods, static class methods, and closure functions. It helps enforce that passed parameters are actually callable.
Explain enums in PHP 8.1 and their benefits.
Enums are a special type of class that represents a fixed set of possible values. They provide type safety, autocompletion, and prevent invalid values. Enums can have methods and implement interfaces, making them more powerful than constant arrays.
What are attributes in PHP 8 and how are they used?
Attributes (also known as annotations in other languages) provide a way to add metadata to classes, methods, properties, parameters, and constants. They are defined using #[] syntax and can be used for configuration, validation, and other metadata purposes.
What are the four fundamental principles of OOP in PHP?
The four fundamental principles are: 1) Encapsulation (bundling data and methods that operate on that data within a single unit), 2) Inheritance (creating new classes that are built upon existing classes), 3) Polymorphism (ability of objects to take on multiple forms), and 4) Abstraction (hiding complex implementation details and showing only functionality).
What is the difference between public, private, and protected visibility modifiers?
public members are accessible from anywhere, private members are only accessible within the declaring class, and protected members are accessible within the declaring class and its child classes. This helps in implementing encapsulation and controlling access to class members.
Explain the concept of method chaining in PHP.
Method chaining is a technique where multiple methods are called on the same object in a single line. It's achieved by returning $this from methods, allowing subsequent method calls. For example: $object->method1()->method2()->method3(). This creates more readable and fluent interfaces.
What is the role of constructor and destructor in a PHP class?
A constructor (__construct) is automatically called when an object is created and is used to initialize object properties. A destructor (__destruct) is called when an object is destroyed or the script ends, used for cleanup tasks. Both are magic methods in PHP.
How does dependency injection work in PHP?
Dependency injection is a design pattern where objects are passed into a class through constructor or setter methods rather than being created inside the class. This reduces coupling, improves testability, and makes the code more maintainable by implementing inversion of control.
What is the difference between static and non-static methods?
Static methods belong to the class itself and can be called without creating an instance of the class. They cannot access non-static properties/methods using $this. Non-static methods belong to class instances and can access all class members. Static methods are called using the scope resolution operator (::).
What are magic methods in PHP and list at least five of them.
Magic methods are special methods that override PHP's default behavior. Common ones include: __construct() (constructor), __destruct() (destructor), __get() (accessing inaccessible properties), __set() (writing to inaccessible properties), __call() (calling inaccessible methods), __toString() (string representation of object).
Explain the concept of composition vs inheritance in PHP.
Composition is when a class contains instances of other classes as properties, while inheritance is when a class extends another class. Composition provides more flexibility and loose coupling ('has-a' relationship) compared to inheritance ('is-a' relationship). Composition is often preferred over inheritance for better maintainability.
What is the purpose of interfaces in PHP?
Interfaces define a contract for classes by specifying which methods must be implemented. They promote loose coupling, enable polymorphism, and allow different classes to share a common contract. A class can implement multiple interfaces, unlike inheritance where a class can only extend one class.
How do abstract classes differ from interfaces?
Abstract classes can have both abstract and concrete methods, while interfaces can only declare method signatures. A class can implement multiple interfaces but extend only one abstract class. Abstract classes can have properties and constructor, while interfaces cannot.
What are traits in PHP and when should they be used?
Traits are mechanisms for code reuse in single inheritance languages like PHP. They allow you to define methods that can be used across multiple independent classes. Traits are useful when you need to share functionality between classes that don't share a common inheritance hierarchy.
Explain late static binding in PHP.
Late static binding refers to a way of using the static keyword to reference the class that was initially called at runtime rather than the class in which the method is defined. It resolves the limitations of self:: by using static:: to refer to the runtime class.
What is method overriding in PHP?
Method overriding occurs when a child class provides a specific implementation for a method that is already defined in its parent class. The child's method must be defined with the same name and parameters. The parent method can be accessed using parent:: keyword.
What is the purpose of the final keyword in PHP classes and methods?
The final keyword prevents child classes from overriding a method when used on methods, and prevents class inheritance when used on classes. It's used when you want to prevent further modification of classes or methods for security or design reasons.
How does autoloading work in PHP?
Autoloading automatically loads PHP classes when they are used, eliminating the need for multiple include statements. It's implemented using spl_autoload_register() function. PSR-4 is the modern standard for autoloading, which maps namespace prefixes to directory structures.
What is the difference between shallow and deep cloning in PHP?
Shallow cloning (default clone keyword) creates a new object with copied scalar properties but maintains references to objects. Deep cloning involves implementing __clone() method to also clone nested objects. Deep cloning ensures complete independence between original and cloned objects.
What are anonymous classes in PHP?
Anonymous classes are classes without names, defined on-the-fly. They are useful when you need a simple, one-off object that implements an interface or extends a class. They're commonly used in testing or when you need quick object creation without formal class definition.
How does property type declaration work in PHP 7.4+?
Property type declarations allow you to specify the type of class properties. They can be scalar types, arrays, classes, interfaces, or nullable types using ?. They ensure type safety at the property level and help catch type-related errors early.
What are constructor property promotion in PHP 8?
Constructor property promotion is a shorthand syntax that allows declaring and initializing class properties directly in the constructor parameter list. It reduces boilerplate code by combining property declaration, constructor parameter, and property assignment in one line.
What is the Observer pattern in PHP and how is it implemented?
The Observer pattern is a behavioral design pattern where objects (observers) automatically notify their dependents (subscribers) about state changes. PHP provides SplSubject and SplObserver interfaces for implementation. It's commonly used for event handling and maintaining consistency between related objects.
What is method overloading in PHP and how is it achieved?
PHP doesn't support traditional method overloading, but it can be simulated using the __call() magic method. This method handles calls to inaccessible or undefined methods, allowing you to implement different behaviors based on the number or types of arguments passed.
What is the role of the instanceof operator in PHP?
The instanceof operator is used to determine if an object is an instance of a specific class, implements an interface, or is an instance of a class that extends another class. It returns true if the object is of the specified type, false otherwise.
How do you implement the Singleton pattern in PHP?
Singleton pattern ensures a class has only one instance. It's implemented by making the constructor private, creating a private static instance property, and a public static method to get the instance. The method creates the instance if it doesn't exist or returns the existing one.
What are value objects in PHP and when should they be used?
Value objects are immutable objects that represent a value rather than an entity. They are used when you need to encapsulate values that have their own business rules and validation. Common examples include Date, Money, or Email value objects.
How do you handle multiple inheritance in PHP?
PHP doesn't support multiple inheritance directly, but it can be achieved through interfaces and traits. A class can implement multiple interfaces and use multiple traits. Traits provide actual method implementations, while interfaces define contracts.
What is the difference between static binding and late static binding?
Static binding (self::) refers to the class where the method is defined, while late static binding (static::) refers to the class that was initially called at runtime. Late static binding allows for more flexible inheritance and method calls in static contexts.
What are named arguments in PHP 8 and how do they benefit OOP?
Named arguments allow you to pass values to a function by specifying the parameter name, regardless of their order. In OOP, this improves code readability, especially with multiple optional parameters, and makes constructor calls and method invocations more explicit and maintainable.
What is the role of __toString() magic method in PHP?
The __toString() magic method allows you to define how an object should be represented as a string. It's automatically called when an object is used in a string context. It must return a string and can be useful for debugging or displaying object information.
What are the different ways to connect to MySQL in PHP?
PHP offers multiple ways to connect to MySQL: 1) MySQLi (object-oriented and procedural), 2) PDO (PHP Data Objects), and 3) mysql_* functions (deprecated, shouldn't be used). PDO is preferred as it supports multiple database types and offers better security features.
What is PDO and what are its advantages?
PDO (PHP Data Objects) is a database abstraction layer providing consistent methods to work with multiple databases. Advantages include: database portability, prepared statements support, consistent error handling, and support for transactions. It provides a secure and flexible approach to database operations.
How do prepared statements help prevent SQL injection?
Prepared statements separate SQL logic from data by using placeholders for values. The database treats these values as data rather than part of the SQL command, preventing injection attacks. Values are automatically escaped, and the query structure remains constant, improving security and performance.
What is database transaction and how is it implemented in PHP?
A transaction is a sequence of operations that must be executed as a single unit. In PHP, transactions are implemented using beginTransaction(), commit(), and rollback() methods. If any operation fails, rollback() ensures all operations are undone, maintaining data integrity.
Explain the difference between mysql_real_escape_string() and prepared statements.
mysql_real_escape_string() escapes special characters in strings, but is deprecated and can be bypassed. Prepared statements are more secure as they separate SQL from data, handle different data types automatically, and are more efficient due to query preparation and caching.
What are the different fetch modes in PDO?
PDO offers several fetch modes: FETCH_ASSOC (returns associative array), FETCH_NUM (returns numeric array), FETCH_BOTH (returns both), FETCH_OBJ (returns object), FETCH_CLASS (returns instance of specified class), and FETCH_LAZY (allows property access of all three).
How do you handle database connection errors in PHP?
Database connection errors can be handled using try-catch blocks with PDOException for PDO, or mysqli_connect_errno() and mysqli_connect_error() for MySQLi. Good practice includes logging errors, displaying user-friendly messages, and implementing connection retry logic.
What is the purpose of LIMIT and OFFSET in SQL queries with PHP?
LIMIT controls the maximum number of records returned, while OFFSET specifies where to start returning records. These are commonly used for pagination. In PHP, they're often used with prepared statements: 'SELECT * FROM table LIMIT ? OFFSET ?'
How do you implement database connection pooling in PHP?
Database connection pooling can be implemented using persistent connections (PDO::ATTR_PERSISTENT), connection management libraries like PHP-CP, or external connection poolers like PgBouncer. This helps reduce connection overhead and improve application performance.
Explain database migrations and their importance.
Database migrations are version control for databases, tracking changes to database schema. They ensure consistent database structure across different environments, enable rollback of changes, and facilitate team collaboration. Tools like Phinx or Laravel Migrations help manage this process.
What are database seeders and when should they be used?
Database seeders are scripts that populate a database with initial or test data. They're useful for development environments, testing, and providing default data. Seeders help ensure consistent data across different environments and make testing more reliable.
How do you optimize database queries in PHP?
Query optimization techniques include: using indexes properly, selecting only needed columns, using EXPLAIN to analyze queries, implementing caching, using prepared statements, limiting result sets, optimizing JOIN operations, and avoiding N+1 query problems.
What is the N+1 query problem and how can it be solved?
N+1 query problem occurs when code executes N additional queries to fetch related data for N results. It can be solved using eager loading (JOIN queries), implementing proper indexing, using subqueries, or utilizing ORM features like with() in Laravel.
How do you implement database sharding in PHP?
Database sharding involves distributing data across multiple databases. Implementation includes: defining sharding key, creating routing logic, managing cross-shard queries, and handling transactions. PHP frameworks or custom implementations can manage connection routing and data distribution.
What are database indexes and when should they be used?
Indexes are data structures that improve the speed of data retrieval operations. They should be used on columns frequently used in WHERE clauses, JOIN conditions, and ORDER BY statements. However, they add overhead to write operations and consume storage space.
How do you handle database deadlocks in PHP applications?
Deadlocks can be handled by: implementing retry logic with try-catch blocks, using proper transaction isolation levels, ordering operations consistently, minimizing transaction duration, implementing timeouts, and logging deadlock incidents for analysis.
What is database normalization and why is it important?
Normalization is organizing database tables to minimize redundancy and dependency. It involves dividing large tables into smaller ones and defining relationships. This improves data integrity, reduces anomalies, and makes the database more efficient and maintainable.
How do you implement database caching in PHP?
Database caching can be implemented using: memory caching (Redis, Memcached), query caching, full-page caching, or ORM caching. Proper cache invalidation strategies, TTL settings, and cache tags help maintain data consistency while improving performance.
What are database triggers and how are they used with PHP?
Triggers are special procedures that automatically execute when certain database events occur (INSERT, UPDATE, DELETE). In PHP, triggers are defined at database level but can be created and managed through PHP code. They help maintain data integrity and automate actions.
How do you implement database replication in PHP applications?
Database replication involves configuring master-slave setup, implementing read-write splitting in code, handling replication lag, and managing failover. PHP applications can use different connections for read/write operations and implement logic to handle replication issues.
What are stored procedures and how are they called in PHP?
Stored procedures are pre-compiled SQL statements stored in the database. In PHP, they're called using CALL statement with PDO or MySQLi. They can improve performance, reduce network traffic, and encapsulate business logic at database level.
How do you handle large dataset processing in PHP?
Large datasets can be handled using: cursor-based pagination, chunked processing, generator functions, memory-efficient algorithms, background job processing, and streaming results. Proper indexing and query optimization are also crucial.
What is database connection lazy loading?
Lazy loading delays database connection initialization until it's actually needed. This saves resources by not establishing connections unnecessarily. It's implemented by wrapping connection logic in methods that are called only when database access is required.
How do you implement database versioning in PHP applications?
Database versioning can be implemented using migration tools, version control for schema files, semantic versioning for database changes, and proper documentation. This ensures consistent database state across environments and facilitates deployment.
What are database views and how are they used in PHP?
Views are virtual tables based on result sets of SQL statements. In PHP, they're queried like regular tables but provide benefits like data abstraction, security through limited access, and simplified complex queries. They help maintain clean application architecture.
How do you implement database backup and recovery in PHP?
Database backup can be implemented using PHP functions to execute system commands, dedicated backup libraries, or framework tools. Important aspects include scheduling backups, compression, secure storage, verification, and testing recovery procedures.
What is database connection pooling and its benefits?
Connection pooling maintains a cache of database connections for reuse, reducing the overhead of creating new connections. Benefits include improved performance, better resource utilization, and connection management. It's especially useful in high-traffic applications.
How do you implement multi-tenancy in PHP applications?
Multi-tenancy can be implemented through separate databases, shared database with separate schemas, or shared tables with tenant IDs. PHP code manages tenant identification, data isolation, and connection routing. Proper security measures ensure data separation.
What are database events and how are they handled in PHP?
Database events are notifications of database changes that can trigger PHP code execution. They can be handled using event listeners, message queues, or polling mechanisms. This enables real-time updates and maintaining data consistency across systems.
How do you implement database connection retry logic in PHP?
Connection retry logic involves implementing exponential backoff, maximum retry attempts, proper error handling, and logging. It helps handle temporary connection issues and improves application reliability. Implementation typically uses try-catch blocks with sleep intervals.
What are the different ways to connect to MySQL in PHP?
PHP offers multiple ways to connect to MySQL: 1) MySQLi (object-oriented and procedural), 2) PDO (PHP Data Objects), and 3) mysql_* functions (deprecated, shouldn't be used). PDO is preferred as it supports multiple database types and offers better security features.
What is PDO and what are its advantages?
PDO (PHP Data Objects) is a database abstraction layer providing consistent methods to work with multiple databases. Advantages include: database portability, prepared statements support, consistent error handling, and support for transactions. It provides a secure and flexible approach to database operations.
How do prepared statements help prevent SQL injection?
Prepared statements separate SQL logic from data by using placeholders for values. The database treats these values as data rather than part of the SQL command, preventing injection attacks. Values are automatically escaped, and the query structure remains constant, improving security and performance.
What is database transaction and how is it implemented in PHP?
A transaction is a sequence of operations that must be executed as a single unit. In PHP, transactions are implemented using beginTransaction(), commit(), and rollback() methods. If any operation fails, rollback() ensures all operations are undone, maintaining data integrity.
Explain the difference between mysql_real_escape_string() and prepared statements.
mysql_real_escape_string() escapes special characters in strings, but is deprecated and can be bypassed. Prepared statements are more secure as they separate SQL from data, handle different data types automatically, and are more efficient due to query preparation and caching.
What are the different fetch modes in PDO?
PDO offers several fetch modes: FETCH_ASSOC (returns associative array), FETCH_NUM (returns numeric array), FETCH_BOTH (returns both), FETCH_OBJ (returns object), FETCH_CLASS (returns instance of specified class), and FETCH_LAZY (allows property access of all three).
How do you handle database connection errors in PHP?
Database connection errors can be handled using try-catch blocks with PDOException for PDO, or mysqli_connect_errno() and mysqli_connect_error() for MySQLi. Good practice includes logging errors, displaying user-friendly messages, and implementing connection retry logic.
What is the purpose of LIMIT and OFFSET in SQL queries with PHP?
LIMIT controls the maximum number of records returned, while OFFSET specifies where to start returning records. These are commonly used for pagination. In PHP, they're often used with prepared statements: 'SELECT * FROM table LIMIT ? OFFSET ?'
How do you implement database connection pooling in PHP?
Database connection pooling can be implemented using persistent connections (PDO::ATTR_PERSISTENT), connection management libraries like PHP-CP, or external connection poolers like PgBouncer. This helps reduce connection overhead and improve application performance.
Explain database migrations and their importance.
Database migrations are version control for databases, tracking changes to database schema. They ensure consistent database structure across different environments, enable rollback of changes, and facilitate team collaboration. Tools like Phinx or Laravel Migrations help manage this process.
What are database seeders and when should they be used?
Database seeders are scripts that populate a database with initial or test data. They're useful for development environments, testing, and providing default data. Seeders help ensure consistent data across different environments and make testing more reliable.
How do you optimize database queries in PHP?
Query optimization techniques include: using indexes properly, selecting only needed columns, using EXPLAIN to analyze queries, implementing caching, using prepared statements, limiting result sets, optimizing JOIN operations, and avoiding N+1 query problems.
What is the N+1 query problem and how can it be solved?
N+1 query problem occurs when code executes N additional queries to fetch related data for N results. It can be solved using eager loading (JOIN queries), implementing proper indexing, using subqueries, or utilizing ORM features like with() in Laravel.
How do you implement database sharding in PHP?
Database sharding involves distributing data across multiple databases. Implementation includes: defining sharding key, creating routing logic, managing cross-shard queries, and handling transactions. PHP frameworks or custom implementations can manage connection routing and data distribution.
What are database indexes and when should they be used?
Indexes are data structures that improve the speed of data retrieval operations. They should be used on columns frequently used in WHERE clauses, JOIN conditions, and ORDER BY statements. However, they add overhead to write operations and consume storage space.
How do you handle database deadlocks in PHP applications?
Deadlocks can be handled by: implementing retry logic with try-catch blocks, using proper transaction isolation levels, ordering operations consistently, minimizing transaction duration, implementing timeouts, and logging deadlock incidents for analysis.
What is database normalization and why is it important?
Normalization is organizing database tables to minimize redundancy and dependency. It involves dividing large tables into smaller ones and defining relationships. This improves data integrity, reduces anomalies, and makes the database more efficient and maintainable.
How do you implement database caching in PHP?
Database caching can be implemented using: memory caching (Redis, Memcached), query caching, full-page caching, or ORM caching. Proper cache invalidation strategies, TTL settings, and cache tags help maintain data consistency while improving performance.
What are database triggers and how are they used with PHP?
Triggers are special procedures that automatically execute when certain database events occur (INSERT, UPDATE, DELETE). In PHP, triggers are defined at database level but can be created and managed through PHP code. They help maintain data integrity and automate actions.
How do you implement database replication in PHP applications?
Database replication involves configuring master-slave setup, implementing read-write splitting in code, handling replication lag, and managing failover. PHP applications can use different connections for read/write operations and implement logic to handle replication issues.
What are stored procedures and how are they called in PHP?
Stored procedures are pre-compiled SQL statements stored in the database. In PHP, they're called using CALL statement with PDO or MySQLi. They can improve performance, reduce network traffic, and encapsulate business logic at database level.
How do you handle large dataset processing in PHP?
Large datasets can be handled using: cursor-based pagination, chunked processing, generator functions, memory-efficient algorithms, background job processing, and streaming results. Proper indexing and query optimization are also crucial.
What is database connection lazy loading?
Lazy loading delays database connection initialization until it's actually needed. This saves resources by not establishing connections unnecessarily. It's implemented by wrapping connection logic in methods that are called only when database access is required.
How do you implement database versioning in PHP applications?
Database versioning can be implemented using migration tools, version control for schema files, semantic versioning for database changes, and proper documentation. This ensures consistent database state across environments and facilitates deployment.
What are database views and how are they used in PHP?
Views are virtual tables based on result sets of SQL statements. In PHP, they're queried like regular tables but provide benefits like data abstraction, security through limited access, and simplified complex queries. They help maintain clean application architecture.
How do you implement database backup and recovery in PHP?
Database backup can be implemented using PHP functions to execute system commands, dedicated backup libraries, or framework tools. Important aspects include scheduling backups, compression, secure storage, verification, and testing recovery procedures.
What is database connection pooling and its benefits?
Connection pooling maintains a cache of database connections for reuse, reducing the overhead of creating new connections. Benefits include improved performance, better resource utilization, and connection management. It's especially useful in high-traffic applications.
How do you implement multi-tenancy in PHP applications?
Multi-tenancy can be implemented through separate databases, shared database with separate schemas, or shared tables with tenant IDs. PHP code manages tenant identification, data isolation, and connection routing. Proper security measures ensure data separation.
What are database events and how are they handled in PHP?
Database events are notifications of database changes that can trigger PHP code execution. They can be handled using event listeners, message queues, or polling mechanisms. This enables real-time updates and maintaining data consistency across systems.
How do you implement database connection retry logic in PHP?
Connection retry logic involves implementing exponential backoff, maximum retry attempts, proper error handling, and logging. It helps handle temporary connection issues and improves application reliability. Implementation typically uses try-catch blocks with sleep intervals.
What is the difference between sessions and cookies in PHP?
Sessions store data on the server with a unique session ID sent to client via cookie, while cookies store data directly on the client's browser. Sessions are more secure for sensitive data and expire when browser closes by default, while cookies can persist for specified durations.
How do you start a session in PHP and what does session_start() do?
session_start() initiates or resumes a session. It must be called before any output is sent to browser. It generates a unique session ID, creates/loads the session file on server, and sets a session cookie. It also loads existing session data into $_SESSION superglobal.
How do you set and retrieve cookies in PHP?
Cookies are set using setcookie() function: setcookie(name, value, expire, path, domain, secure, httponly). They can be retrieved using $_COOKIE superglobal array. Parameters control cookie lifetime, visibility, and security settings.
What are the security considerations when working with sessions?
Key security considerations include: using session_regenerate_id() to prevent session fixation, setting secure and httponly flags, implementing session timeout, validating session data, proper session destruction, and securing session storage location.
How do you implement session timeout in PHP?
Session timeout can be implemented by: setting session.gc_maxlifetime in php.ini, storing last activity timestamp in session, checking elapsed time on each request, and destroying session if timeout exceeded. Also consider implementing sliding expiration.
What is session hijacking and how can it be prevented?
Session hijacking occurs when attacker steals session ID to impersonate user. Prevention includes: using HTTPS, setting secure/httponly flags, regenerating session IDs, implementing IP validation, using token-based authentication, and proper session timeout.
How do you destroy a session in PHP?
Complete session destruction requires: session_unset() to clear variables, session_destroy() to destroy session data, clearing session cookie using setcookie(), and unset($_SESSION) array. Best practice includes clearing all related cookies and session data.
What are the different session storage handlers in PHP?
PHP supports various session handlers: files (default), database, memcached, redis. Custom handlers can be implemented using SessionHandler interface. Each has advantages for different scenarios (scalability, persistence, performance).
How do you implement remember me functionality using cookies?
Remember me involves: generating secure token, storing hashed token in database, setting long-lived cookie with token, validating token on subsequent visits. Implementation should include token rotation, secure storage, and proper expiration handling.
What is session fixation and how to prevent it?
Session fixation occurs when attacker sets victim's session ID. Prevention includes: regenerating session ID on login/privilege change using session_regenerate_id(true), validating session data, and implementing proper session security measures.
How do you handle session data in distributed environments?
Distributed sessions require: centralized storage (Redis/Memcached), consistent session handling across servers, proper load balancing configuration, implementing sticky sessions or session replication, and handling failover scenarios.
What are the limitations of cookies and how to work around them?
Cookie limitations include: size (4KB), number per domain, browser settings blocking cookies. Workarounds include: using local storage for larger data, implementing fallback mechanisms, splitting data across multiple cookies, server-side storage alternatives.
How do you implement secure session validation?
Secure session validation includes: checking user agent consistency, validating IP address (with caution), implementing CSRF tokens, validating session age, checking session data integrity, and implementing proper authentication checks.
What is the purpose of session_cache_limiter() and its options?
session_cache_limiter() controls HTTP caching of pages with sessions. Options include: nocache, private, public, private_no_expire. Affects how browsers and proxies cache session pages. Important for security and proper page caching.
How do SameSite cookies work and why are they important?
SameSite cookie attribute controls how cookie is sent with cross-site requests. Values: Strict, Lax, None. Helps prevent CSRF attacks and protects against cross-site request attacks. Important for modern web security compliance.
What are session configuration options in php.ini?
Key options include: session.save_handler, session.save_path, session.gc_maxlifetime, session.cookie_lifetime, session.cookie_secure, session.cookie_httponly. These control session behavior, storage, lifetime, and security settings.
How do you implement custom session handling?
Custom session handling requires implementing SessionHandlerInterface with methods: open, close, read, write, destroy, gc. Used for custom storage solutions or specific session management requirements. Must handle all session operations properly.
What is session garbage collection and how does it work?
Garbage collection removes expired session data. Controlled by session.gc_probability, session.gc_divisor, and session.gc_maxlifetime settings. Process runs randomly based on probability settings. Important for server resource management.
How do you handle session expiration in AJAX applications?
AJAX session handling includes: implementing session checks in AJAX calls, handling session timeout responses, providing user feedback, implementing automatic logout, and managing session refresh mechanisms. Consider implementing keepalive requests.
What are HTTP-only cookies and their importance?
HTTP-only cookies cannot be accessed by JavaScript, protecting against XSS attacks. Set using httponly parameter in setcookie() or session configuration. Important security measure for sensitive cookies like session IDs.
How do you implement session-based authentication?
Session authentication involves: validating credentials, storing user data in session, implementing session security measures, handling remember me functionality, implementing proper logout, and managing session expiration.
What is flash session data and how is it implemented?
Flash data persists for only one request cycle, commonly used for temporary messages. Implementation involves storing data in session, checking for data existence, displaying data, and removing after use. Often used for success/error messages.
How do you handle concurrent session access?
Concurrent access handling includes: implementing session locking mechanisms, using database transactions for session storage, handling race conditions, implementing proper session state management, and considering distributed session storage.
What are secure cookies and when should they be used?
Secure cookies are only transmitted over HTTPS. Set using secure parameter in setcookie() or session configuration. Should be used for all sensitive data and session cookies when site uses HTTPS. Essential for maintaining transport security.
How do you implement session persistence across subdomains?
Cross-subdomain sessions require: setting session cookie domain to main domain, configuring session handler for shared access, managing session security across subdomains, and handling domain-specific session data appropriately.
What are the best practices for session security in PHP?
Best practices include: using HTTPS, setting secure/httponly flags, implementing proper session timeout, regenerating session IDs, validating session data, secure storage, proper destruction, and implementing CSRF protection.
How do you implement session migration?
Session migration involves: copying session data to new storage, updating session handler configuration, managing transition period, handling failover scenarios, and ensuring data consistency. Important for system upgrades or architecture changes.
What are domain cookies and their use cases?
Domain cookies are accessible across subdomains. Set using domain parameter in setcookie(). Used for maintaining user state across subdomains, implementing single sign-on, sharing necessary data between related sites. Requires careful security consideration.
How do you handle session synchronization in multi-server environments?
Multi-server synchronization requires: centralized session storage, consistent configuration across servers, handling race conditions, implementing proper locking mechanisms, and managing session replication or shared storage.
What is session adoption and its security implications?
Session adoption occurs when taking over existing session. Security implications include: potential session fixation attacks, need for proper validation, importance of session regeneration, and implementing proper authentication checks. Requires careful implementation.
What are the basic file operations available in PHP?
PHP provides several basic file operations: fopen() for opening files, fread()/fwrite() for reading/writing, file_get_contents()/file_put_contents() for simple operations, fclose() for closing files, and unlink() for deletion. Additional functions include copy(), rename(), and file_exists().
How do you handle file uploads securely in PHP?
Secure file uploads require: validating file types, checking MIME types, setting upload size limits, using move_uploaded_file(), scanning for malware, storing files outside web root, using random filenames, setting proper permissions, and validating file contents.
What are the different file opening modes in PHP?
PHP supports several file modes: 'r' (read-only), 'w' (write, truncate), 'a' (append), 'r+' (read and write), 'w+' (read and write, truncate), 'a+' (read and append). Adding 'b' for binary mode. Each mode affects file pointer position and file handling behavior.
How do you handle large file operations efficiently in PHP?
Large file handling techniques include: using fgets() for line-by-line reading, implementing chunked reading/writing, using generators, setting proper memory limits, implementing progress tracking, and using stream functions for memory efficiency.
What are PHP streams and how are they used?
Streams provide a unified way to handle file, network, and compression operations. Used with stream_get_contents(), fopen() with stream wrappers (file://, http://, ftp://, etc.). Support filters and contexts for advanced operations.
How do you manage file permissions in PHP?
File permissions are managed using chmod() function, umask() for default permissions. Functions like is_readable(), is_writable() check permissions. Important for security. Permissions should follow principle of least privilege.
What are directory operations available in PHP?
Directory operations include: mkdir() for creation, rmdir() for deletion, opendir()/readdir()/closedir() for reading, scandir() for listing contents, dirname()/basename() for path manipulation, and is_dir() for checking directory existence.
How do you implement file download functionality securely?
Secure file downloads require: validating file paths, checking permissions, setting proper headers (Content-Type, Content-Disposition), implementing rate limiting, scanning files, and using readfile() or fpassthru() for streaming.
What are the common file system security vulnerabilities?
Common vulnerabilities include: directory traversal, file inclusion attacks, insufficient permissions, insecure file uploads, path manipulation, and race conditions. Prevention requires proper validation, sanitization, and secure coding practices.
How do you handle temporary files in PHP?
Temporary files managed using tmpfile() for automatic cleanup, tempnam() for custom temp files. Important to implement proper cleanup, set secure permissions, use system temp directory, and handle concurrent access properly.
What are file locking mechanisms in PHP?
File locking uses flock() function with LOCK_SH (shared), LOCK_EX (exclusive), LOCK_UN (release). Important for preventing race conditions in concurrent access. Should implement proper error handling and timeout mechanisms.
How do you handle CSV file operations in PHP?
CSV operations use fgetcsv()/fputcsv() for reading/writing, handling different delimiters and enclosures. Consider character encoding, handling large files, validating data, and implementing proper error handling.
What are symbolic links and how are they handled in PHP?
Symbolic links managed with symlink(), readlink(), and is_link() functions. Security considerations include proper validation, handling recursive links, and implementing access controls. Important for file system organization.
How do you implement file caching mechanisms?
File caching involves: implementing cache directory structure, managing cache lifetime, handling cache invalidation, implementing file locking for concurrent access, and proper error handling. Consider using existing caching libraries.
What are memory-mapped files and their usage in PHP?
Memory-mapped files accessed using php-io extension, providing efficient access to large files. Benefits include faster access and shared memory capabilities. Consider memory limitations and proper resource management.
How do you handle file compression in PHP?
File compression using zlib functions (gzopen, gzwrite, gzread) or ZIP extension. Important considerations include compression ratio, memory usage, handling large files, and proper error handling.
What are file metadata operations in PHP?
Metadata operations include: stat(), filemtime(), filesize(), filetype(). Provide information about file properties, modification times, and attributes. Important for file management and caching implementations.
How do you implement file backup functionality?
File backup implementation includes: copying files with versioning, implementing rotation system, handling large files, compression, secure storage, verification, and proper error handling. Consider automated backup scheduling.
What is the difference between include and require in PHP?
include produces warning on failure, require produces fatal error. require_once and include_once prevent multiple inclusions. Choose based on dependency criticality. Important for modular code organization.
How do you handle file type detection in PHP?
File type detection using: finfo_file(), mime_content_type(), pathinfo(), checking file extensions. Important for security in file uploads. Should not rely solely on file extensions for validation.
What are atomic file operations and their importance?
Atomic operations ensure file operation completeness without interruption. Use rename() for atomic writes, implement proper locking, handle temporary files correctly. Important for data integrity and concurrent access.
How do you handle file path manipulation securely?
Secure path manipulation using realpath(), basename(), dirname(). Prevent directory traversal, validate paths against whitelist, use proper encoding, and implement access controls. Important for security.
What are file streams filters and their usage?
Stream filters modify data as it's read/written. Used with stream_filter_append(), stream_filter_register(). Common for encryption, compression, character encoding. Consider performance impact and proper error handling.
How do you implement file monitoring functionality?
File monitoring involves checking file changes using filemtime(), implementing polling or inotify extension, handling multiple files, logging changes, and proper resource management. Consider performance impact.
What are memory considerations in file operations?
Memory considerations include: using streaming for large files, proper chunk sizes, clearing file handles, implementing garbage collection, monitoring memory usage, and setting appropriate memory limits. Important for performance.
How do you handle file encoding issues?
Encoding issues handled using mb_* functions, setting proper encoding in fopen(), handling BOM, implementing conversion functions. Important for international character support and data integrity.
What are file ownership operations in PHP?
File ownership managed using chown(), chgrp() functions. Important for security and permissions management. Consider system-level permissions, proper error handling, and security implications.
How do you implement file cleanup routines?
File cleanup includes: implementing age-based deletion, handling temporary files, proper permission checking, implementing logging, and error handling. Consider automated scheduling and resource management.
What are best practices for file system security?
Best practices include: proper permissions, input validation, path sanitization, secure file operations, implementing access controls, proper error handling, and following principle of least privilege. Regular security audits recommended.
How do you handle file system errors and exceptions?
Error handling includes: try-catch blocks, checking return values, implementing logging, proper user feedback, and recovery mechanisms. Consider different error types and appropriate response strategies.
What are the advantages of using PHP frameworks?
PHP frameworks provide: structured development patterns, built-in security features, database abstraction, code reusability, MVC architecture, robust routing systems, template engines, built-in tools for testing, and faster development cycles. They also enforce consistent coding standards.
What is Laravel and what are its key features?
Laravel is a popular PHP framework featuring: Eloquent ORM, Blade templating, Artisan CLI, built-in security, database migrations, authentication system, task scheduling, queue management, real-time events, and extensive package ecosystem via Composer.
Explain Dependency Injection in modern PHP frameworks.
Dependency Injection is a design pattern where dependencies are 'injected' into objects rather than created inside them. Frameworks use DI containers to manage object creation and lifecycle. This promotes loose coupling, testability, and maintainable code.
What is the MVC pattern and how is it implemented in PHP frameworks?
MVC (Model-View-Controller) separates application logic: Models handle data/business logic, Views handle presentation, Controllers handle request flow. Frameworks provide structure and base classes for each component, promoting organized and maintainable code.
How does routing work in modern PHP frameworks?
Routing maps URLs to controller actions. Features include: route parameters, middleware, route groups, named routes, resource routing. Frameworks handle request parsing, parameter binding, and response generation. Supports RESTful routing patterns.
What is Symfony and its component-based architecture?
Symfony is a framework and component library. Key features: reusable components, dependency injection, event dispatcher, console tools, security system. Components can be used independently in other projects. Follows SOLID principles.
Explain middleware in PHP frameworks.
Middleware processes HTTP requests/responses before reaching controllers. Used for: authentication, CSRF protection, logging, request modification. Can be global or route-specific. Implements pipeline pattern for request handling.
What are ORMs and how are they used in PHP frameworks?
Object-Relational Mappers (ORMs) like Eloquent or Doctrine map database tables to objects. Features: relationship handling, query building, migrations, model events. Simplifies database operations and provides abstraction layer.
How do template engines work in PHP frameworks?
Template engines (Blade, Twig) provide syntax for views. Features: template inheritance, sections, partials, escaping, custom directives. Compiles templates to plain PHP for performance. Separates logic from presentation.
What is service container/IoC container in PHP frameworks?
Service containers manage class dependencies and instantiation. Features: automatic resolution, binding interfaces to implementations, singleton patterns, contextual binding. Core to dependency injection implementation.
Explain event handling in PHP frameworks.
Events allow decoupled communication between components. Features: event dispatchers, listeners, broadcasters, queued events. Used for logging, notifications, cache clearing, etc. Supports synchronous and asynchronous processing.
What are migrations and seeders in PHP frameworks?
Migrations version control database schema changes. Seeders populate databases with test/initial data. Features: rollback capability, timestamps, factory patterns. Essential for database version control and testing.
How is authentication handled in PHP frameworks?
Frameworks provide authentication systems with: user providers, guards, middleware, password hashing, remember me functionality, OAuth support. Includes session management, token authentication, and multiple authentication schemes.
What is CodeIgniter and its key features?
CodeIgniter is lightweight framework featuring: small footprint, simple configuration, built-in security, database abstraction, form/data validation, session handling. Known for simplicity, performance, and minimal configuration.
How do PHP frameworks handle caching?
Frameworks provide caching systems supporting: file, database, memory (Redis/Memcached) caching. Features include: cache tags, atomic locks, cache drivers, automatic cache clearing. Important for performance optimization.
Explain queue systems in PHP frameworks.
Queues handle asynchronous task processing. Features: multiple drivers (database, Redis, etc.), job retries, rate limiting, scheduled jobs. Used for emails, notifications, and resource-intensive tasks.
What are service providers in PHP frameworks?
Service providers bootstrap application services. Handle: service registration, boot operations, package configuration, event registration. Core to framework initialization and package integration.
How do PHP frameworks handle form validation?
Frameworks provide validation systems with: built-in rules, custom validators, error messaging, form requests, CSRF protection. Supports client and server-side validation, file validation, and complex validation scenarios.
What are facades in Laravel and similar patterns in other frameworks?
Facades provide static interface to underlying classes. Offer convenient syntax for common services. Implementation varies: Laravel uses facade pattern, others use static proxies or service locators.
How do PHP frameworks implement security features?
Security features include: CSRF protection, XSS prevention, SQL injection protection, authentication, authorization, encryption, password hashing. Frameworks provide middleware and helpers for common security needs.
What are artisan commands in Laravel and similar CLI tools?
CLI tools provide commands for common tasks: generating code, running migrations, clearing cache, scheduling tasks. Support custom commands, interactive mode. Essential for development and deployment workflows.
How do PHP frameworks handle API development?
Frameworks provide API tools: resource controllers, API authentication, rate limiting, response formatting, versioning support. Include features for RESTful APIs, API documentation, and testing.
Explain testing features in PHP frameworks.
Frameworks include testing tools: unit testing, feature testing, browser testing, mocking, assertions. Support PHPUnit integration, database testing, HTTP testing. Essential for maintaining code quality.
What is Lumen and when should it be used?
Lumen is Laravel's micro-framework for microservices and APIs. Features: fast routing, basic Laravel features, minimal overhead. Best for simple applications, APIs where full framework unnecessary.
How do PHP frameworks handle localization?
Localization features include: language files, translation helpers, plural forms, date/number formatting. Support multiple languages, language switching, fallback locales. Important for international applications.
What are observers and model events in PHP frameworks?
Observers/events handle model lifecycle events (create, update, delete). Used for: maintaining related data, sending notifications, logging changes. Helps separate concerns and maintain clean models.
How do PHP frameworks implement authorization?
Authorization systems include: roles, permissions, policies, gates. Features ACL management, policy-based authorization, role hierarchies. Integrates with authentication and middleware systems.
What are contracts/interfaces in PHP frameworks?
Contracts define framework component interfaces. Enable loose coupling, easy testing, component replacement. Core to framework extensibility and maintainability. Follow interface segregation principle.
How do PHP frameworks handle file storage?
File storage abstraction supports: local storage, cloud storage (S3, etc.), FTP. Features include: file uploads, storage drivers, file operations, URL generation. Provides consistent interface across storage systems.
What are collections in PHP frameworks?
Collections provide fluent interface for array operations. Features: mapping, filtering, reducing, sorting, grouping. Extends array functionality with object-oriented interface. Important for data manipulation.
What is REST API and its core principles?
REST (Representational State Transfer) is an architectural style with principles: statelessness, client-server separation, cacheable resources, uniform interface, layered system. Uses HTTP methods (GET, POST, PUT, DELETE) for CRUD operations.
How do you implement API authentication in PHP?
API authentication methods include: JWT tokens, OAuth 2.0, API keys, Basic Auth, Bearer tokens. Implementation involves token generation, validation, middleware for protection, and proper error handling. Consider security best practices like token expiration.
What are the best practices for API response formatting?
Best practices include: consistent response structure, proper HTTP status codes, clear error messages, pagination metadata, proper content type headers. Use envelope pattern when needed, handle nested resources, implement proper serialization.
How do you implement API versioning?
Versioning strategies include: URI versioning (v1/api), header versioning (Accept header), query parameter versioning. Consider backward compatibility, deprecation policies, documentation. Choose strategy based on client needs.
What is rate limiting and how is it implemented?
Rate limiting controls request frequency. Implementation includes: tracking requests per client, setting time windows, using tokens/keys, implementing cooldown periods. Use Redis/cache for distributed systems. Return proper headers for limit status.
How do you handle CORS in PHP APIs?
CORS (Cross-Origin Resource Sharing) handled through proper headers: Access-Control-Allow-Origin, Allow-Methods, Allow-Headers. Implementation includes preflight requests handling, proper middleware configuration, security considerations.
What are API resources and transformers?
Resources/transformers format API responses: converting models to JSON/arrays, handling relationships, hiding sensitive data. Features include conditional attributes, nested resources, custom transformations. Important for consistent response formatting.
How do you implement API caching?
API caching strategies include: HTTP cache headers, response caching, query result caching. Use ETags, Cache-Control headers, implement cache invalidation. Consider cache layers (client, CDN, server) and cache lifetime.
What is GraphQL and how does it compare to REST?
GraphQL is query language for APIs. Features: single endpoint, client-specified data, strong typing, real-time with subscriptions. Differs from REST in data fetching, versioning approach, and response structure. Consider use case for implementation.
How do you handle file uploads in APIs?
File upload handling includes: multipart form data, proper validation, secure storage, progress tracking. Consider chunked uploads for large files, implement proper error handling, use secure file operations.
What are webhooks and how are they implemented?
Webhooks are HTTP callbacks for real-time notifications. Implementation includes: endpoint registration, payload signing, retry logic, event queuing. Consider security, validation, and proper error handling.
How do you implement API documentation?
API documentation tools include: Swagger/OpenAPI, API Blueprint, automated documentation generation. Include: endpoints, parameters, responses, examples. Keep documentation updated, consider interactive documentation.
What are the common API security threats?
Common threats include: injection attacks, unauthorized access, MITM attacks, DoS/DDoS, data exposure. Implement: authentication, rate limiting, input validation, proper encryption, secure headers.
How do you implement API testing?
API testing includes: unit tests, integration tests, end-to-end tests. Use tools like PHPUnit, Postman, automated testing. Test authentication, validation, error cases, performance. Implement CI/CD pipeline.
What is API throttling and its implementation?
Throttling controls API usage by limiting request rate/volume. Implementation includes: token bucket algorithm, sliding window, concurrent request limiting. Consider user tiers, custom limits, proper error responses.
How do you handle API errors and exceptions?
Error handling includes: proper HTTP status codes, consistent error format, detailed messages, error logging. Implement global exception handler, format exceptions properly, consider security in error messages.
What is OAuth 2.0 and its implementation?
OAuth 2.0 is authorization framework. Implementation includes: authorization flows, token management, scope handling, refresh tokens. Consider security best practices, proper flow selection, token storage.
How do you implement API pagination?
Pagination methods include: offset/limit, cursor-based, page-based. Include metadata (total, next/prev links), handle large datasets, implement proper caching. Consider performance and use case requirements.
What are JSON Web Tokens (JWT)?
JWTs are encoded tokens containing claims. Structure: header, payload, signature. Used for authentication/authorization. Implementation includes token generation, validation, refresh mechanisms. Consider security implications.
How do you handle API logging and monitoring?
Logging/monitoring includes: request/response logging, error tracking, performance metrics, usage analytics. Implement proper log levels, monitoring tools integration, alerting systems. Consider privacy and security.
What is API gateway and its benefits?
API gateway provides single entry point for multiple services. Features: request routing, authentication, rate limiting, caching, monitoring. Benefits include centralized control, security, scalability.
How do you implement API request validation?
Request validation includes: input sanitization, schema validation, type checking, business rule validation. Implement validation middleware, proper error responses, custom validation rules. Consider performance impact.
What are microservices and their implementation?
Microservices are small, independent services. Implementation includes: service communication, data consistency, deployment strategies, service discovery. Consider scalability, monitoring, error handling.
How do you handle API performance optimization?
Optimization includes: response caching, query optimization, proper indexing, compression, connection pooling. Consider bottlenecks, monitoring, scaling strategies. Implement proper profiling.
What is API composition and aggregation?
Composition combines multiple API calls into single endpoint. Aggregation combines data from multiple services. Consider performance, error handling, data consistency. Implement proper caching strategies.
How do you implement API search functionality?
Search implementation includes: query parameters, filtering, sorting, full-text search. Consider search engines integration, performance optimization, proper indexing. Implement relevance scoring.
What are API design patterns?
Common patterns include: Repository, Factory, Strategy, Observer, Adapter. Used for code organization, maintainability, scalability. Consider use case requirements, team familiarity, implementation complexity.
How do you handle API deprecation?
Deprecation strategy includes: versioning, notification period, documentation updates, migration guides. Implement warning headers, monitoring deprecated usage, proper communication. Consider client impact.
What is API orchestration?
Orchestration coordinates multiple API calls/services. Includes: workflow management, error handling, rollback mechanisms. Consider transaction management, service dependencies, monitoring. Implement proper logging.
How do you implement API analytics?
Analytics implementation includes: usage tracking, performance metrics, error rates, user behavior. Consider data collection, storage, visualization tools. Implement proper privacy measures.
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