Question:Write down  CodeIgniter  features? 

CodeIgniter's main features are:

 Model-View-Controller Based System
 Extremely Light Weight
 Full Featured database classes with support for several platforms.
 Active Record Database Support
 Form and Data Validation
 Security and XSS Filtering
 Session Management
 Email Sending Class. Supports Attachments, HTML/Text email, multiple protocols (sendmail, SMTP, and Mail) and more.
 Image Manipulation Library (cropping, resizing, rotating, etc.). Supports GD, ImageMagick, and NetPBM
 File Uploading Class
 FTP Class
 Localization
 Pagination
 Data Encryption
 Benchmarking
 Full Page Caching
 Error Logging
 Application Profiling
 Calendaring Class
 User Agent Class
 Zip Encoding Class
 Template Engine Class
 Trackback Class
 XML-RPC Library
 Unit Testing Class
 Search-engine Friendly URLs
 Flexible URI Routing
 Support for Hooks and Class Extensions
 Large library of "helper" functions

Question:What do you mean by web service? How many ways we build webservice? 

 Webservice:A software system designed to support interoperable machine-to-machine interaction over a network. 

There are a number of ways in which we can bulid a web service:
a.      Remote Procedure call with XML-RPC
b.     Representational State Transfer with RESTful method

Question:What are bottlenecks and what are the types of bottlenecks? 

A bottleneck is part of application that is slower than the other parts, and that is slowing down the application as a whole. Here are a number of different types of bottlenecks:
 Database
API
Bandwidth
Static
Code

Question:What do you mean by benchmarks? 

Benchmarks let us log the time it takes for a part, or multiple parts, of our application to run. Once we have benchmarked our application, we can generate a report to see the timings of our application wherever we set a benchmark. We can then seek out any bottlenecks in our application, and rectify them.

Question:How does security can be provided in CodeIgniter? 

CodeIginter provides a number of security options to handle to our applications:
a. URL security
b, Global security
c. Filtering data
d. Password salting
e. Database security
f. Cross-site scripting

Question:Write the functions of Email class. 

There is a number of email class functions available in CodeIginter:
$this->email->from()
$this->email->reply_to()
$this->email->to() 
$this->email->cc() 
$this->email->bcc()
$this->email->subject()
$this->email->message() 
$this->email->set_alt_message() 
$this->email->clear() 
$this->email->send() 
$this->email->attach() 
$this->email->print_debugger()

Question:What is a library? 

A CodeIgniter library is simply a class file that abstracts functionality into easy-to-use functions tha take much of the strain off the developer. The term "class" and "library" are used interchangeably in CodeIgniter.

Question:What is stored in a session when you use session class? 

A codeIgniter session is simply an array containing the following data:

1. The user's unique Session ID
2. The use's IP address
3. The user's User Agent string
4. The "Last activity" timestamp

Question:Define the term "Session ID". 

Session ID: This is a randomly-generated number, which is hashed with MD5 for portability, and is regenerated every five minutes.

Question:What is the purpose of Flash data? 

CodeIgniter supports flashdata - data that is only available for one server request, and then removed. Flash data is very useful, and is usually used for informational messages such as "You hava been logged out" or "Removed user account". Flash variable are prefixed with flash_.