What do you mean by design patterns (php) ?

Questions on OOP concepts 1. What are the access specifiers available in php ? Explain 2. What is object cloning ? 3. What are the differences between interface and abstract class ? 4. What is overloading ? 5. What is overriding ? 6. How to prevent function overriding ? 7. What is the use of "final" keyword ? 8. What is static variable ? How will access a static variable ? What is static class ?

What is happening in the following code $objA = new A(); // A is a class $objB = $objA;

What do you mean by MVC ?

Design a class that should always return a single object ?

What is mem_cache ? How do you put a database query into that ?

Dear Sir, i am a frasher and now i got a job offer from AentteQ Software Technologies for PHP developer.. so i am in confusion that is PHP correct for my carrer or i shud choose other then php for my carrer...plz suggest me

4 down vote favorite share [g+] share [fb] share [tw] I am developing my site using server side sessions using redis as backend for saving the session. Now the issue which is bothering me is of user leaving the website without logging out. I mean user simply closes the browser which causes the cookie to be deleted. Now session of that user still exists on the server and will not be used again as new login requires creating a new session due to security reasons. To avoid the case where hacker steals the old cookie and use it after user login again with same old session id. In essence user leaves the website without explicitly logging out and his session will be deleted after certain time limit of inaccessibility. I am thinking time limit of 30-60 minutes. Also with every new request from user his cookie will also be updated to keep track of when the user last time accessed the site. But nowadays, people let site remain open for long time without accessing it. For example users open facebook and gmail in new tabs and forget about them for 2-3 hours and still they are not asked to login again. Is letting a 2-3 hours old cooke access the session secure? My concern is someone steals user cookie and use it 2-3 hours later. Thinking on this topic has also forced me to question how facebook manages security if user can use a session where they are not accessing it for long periods of time and still they remain logged in. Or is it not secure for me to keep logged in when am not accessing the site session for longer period of time? It can be the case also there is some pinging mechanism using which sites keep track of user having their site open in a browser and when browser closes they are notified and can work accordingly. My website is a social network and needs all those security and usage features which a social network may need. I am new to web security and web development in general and may be the case where my above questions may seem a little basic. If you feel that is the case kindly point to some good reference where I can read and find answers to my question.