Named Pipes (FIFOs - First In First Out)

Named Pipes (FIFOs - First In First Out)
Basic Concepts
A named pipe works much like a regular pipe, but does have some noticeable differences.
Named pipes exist as a device special file in the file system.
Processes of different ancestry can share data through a named pipe.
When all I/O is done by sharing processes, the named pipe remains in the file system for later use.

To create a FIFO in C, we can make use of the mknod() system call:

LIBRARY FUNCTION: mknod();

PROTOTYPE: int mknod( char *pathname, mode_t mode, dev_t dev);
RETURNS: 0 on success,
-1 on error: errno = EFAULT (pathname invalid)
EACCES (permission denied)
ENAMETOOLONG (pathname too long)
ENOENT (invalid pathname)
ENOTDIR (invalid pathname)
(see man page for mknod for others)

NOTES: Creates a filesystem node (file, device file, or FIFO)

I will leave a more detailed discussion of mknod() to the man page, but let's consider a simple example of FIFO creation from C:
mknod("/tmp/MYFIFO", S_IFIFO|0666, 0);
In this case, the file ``/tmp/MYFIFO'' is created as a FIFO file. The requested permissions are ``0666'', although they are affected by the umask setting as follows:
final_umask = requested_permissions & ~original_umask
A common trick is to use the umask() system call to temporarily zap the umask value:
umask(0);
mknod("/tmp/MYFIFO", S_IFIFO|0666, 0);
In addition, the third argument to mknod() is ignored unless we are creating a device file. In that instance, it should specify the major and minor numbers of the device file.
FIFO Operations
I/O operations on a FIFO are essentially the same as for normal pipes, with once major exception. An ``open'' system call or library function should be used to physically open up a channel to the pipe. With half-duplex pipes, this is unnecessary, since the pipe resides in the kernel and not on a physical filesystem. In our examples, we will treat the pipe as a stream, opening it up with fopen(), and closing it with fclose().
Consider a simple server process:
/*****************************************************************************

*****************************************************************************
MODULE: fifoserver.c
*****************************************************************************/

#include // here stdio.h
#include // here stdlib.h
#include // here sys/stat.h
#include // here unistd.h

#include // here linux/stat.h

#define FIFO_FILE "MYFIFO"

int main(void)
{
FILE *fp;
char readbuf[80];

/* Create the FIFO if it does not exist */
umask(0);
mknod(FIFO_FILE, S_IFIFO|0666, 0);

while(1)
{
fp = fopen(FIFO_FILE, "r");
fgets(readbuf, 80, fp);
printf("Received string: %s\n", readbuf);
fclose(fp);
}

return(0);
}
Since a FIFO blocks by default, run the server in the background after you compile it:
$ fifoserver&
We will discuss a FIFO's blocking action in a moment. First, consider the following simple client frontend to our server:

/* MODULE: fifoclient.c

*****************************************************************************/

#include // here stdio.h
#include // here stdlib.h

#define FIFO_FILE "MYFIFO"

int main(int argc, char *argv[])
{
FILE *fp;

if ( argc != 2 ) {
printf("USAGE: fifoclient [string]\n");
exit(1);
}

if((fp = fopen(FIFO_FILE, "w")) == NULL) {
perror("fopen");
exit(1);
}

fputs(argv[1], fp);

fclose(fp);
return(0);
}
Blocking Actions on a FIFO
Normally, blocking occurs on a FIFO. In other words, if the FIFO is opened for reading, the process will "block" until some other process opens it for writing. This action works vice-versa as well. If this behavior is undesirable, the O_NONBLOCK flag can be used in an open() call to disable the default blocking action.
In the case with our simple server, we just shoved it into the background, and let it do its blocking there. The alternative would be to jump to another virtual console and run the client end, switching back and forth to see the resulting action.


The Infamous SIGPIPE Signal
On a last note, pipes must have a reader and a writer. If a process tries to write to a pipe that has no reader, it will be sent the SIGPIPE signal from the kernel. This is imperative when more than two processes are involved in a pipeline.

Frequently Asked Questions In Operating System Concepts

What is MUTEX ?
What isthe difference between a 'thread' and a 'process'?
What is INODE?
Explain the working of Virtual Memory.
How does Windows NT supports Multitasking?
Explain the Unix Kernel.
What is Concurrency? Expain with example Deadlock and Starvation.
What are your solution strategies for "Dining Philosophers Problem" ?
Explain Memory Partitioning, Paging, Segmentation.
Explain Scheduling.
Operating System Security.
What is Semaphore?
Explain the following file systems : NTFS, Macintosh(HPFS), FAT .
What are the different process states?
What is Marshalling?
Define and explain COM?
What is Marshalling?
Difference - Loading and Linking ?
What are the basic functions of an operating system?
Explain briefly about, processor, assembler, compiler, loader, linker and the functions executed by them.
What are the difference phases of software development? Explain briefly?
Differentiate between RAM and ROM?
What is DRAM? In which form does it store data?
What is cache memory?
What is hard disk and what is its purpose?
Differentiate between Complier and Interpreter?
What are the different tasks of Lexical analysis?
What are the different functions of Syntax phase, Sheduler?
What are the main difference between Micro-Controller and Micro- Processor?
Describe different job scheduling in operating systems.
What is a Real-Time System ?
What is the difference between Hard and Soft real-time systems ?
What is a mission critical system ?
What is the important aspect of a real-time system ?
If two processes which shares same system memory and system clock in a distributed system, What is it called?
What is the state of the processor, when a process is waiting for some event to occur?
What do you mean by deadlock?
Explain the difference between microkernel and macro kernel.
Give an example of microkernel.
When would you choose bottom up methodology?
When would you choose top down methodology?
Write a small dc shell script to find number of FF in the design.
Why paging is used ?
Which is the best page replacement algorithm and Why? How much time is spent usually in each phases and why?
Difference between Primary storage and secondary storage?
What is multi tasking, multi programming, multi threading?
Difference between multi threading and multi tasking?
What is software life cycle?
Demand paging, page faults, replacement algorithms, thrashing, etc.
Explain about paged segmentation and segment paging
While running DOS on a PC, which command would be used to duplicate the entire diskette?

---> OS multiple choice questions ---->

Multiple Choice Questions On Operating System Part-6

1) The high paging activity is called ________.
1 Inter process communication
2 Thrashing
3 Context Switch
4 None of the above
Right Ans ) 2

2) The Hardware mechanism that enables a device to notify the CPU is called __________.
1 Polling
2 Interrupt
3 System Call
4 None of the above
Right Ans ) 2

3) In the running state
1 only the process which has control of the processor is found
2 all the processes waiting for I/O to be completed are found
3 all the processes waiting for the processor are found
4 none of the above
Right Ans ) 1

4) Which of the following is crucial time while accessing data on the disk?
1 Seek time
2 Rotational time
3 Transmission time
4 Waiting time
Right Ans ) 1

5) Process State is a part of
1 Process Control block
2 Inode
3 File Allocation Table
4 None of the above
Right Ans ) 1

6) Who is called a supervisor of computer acitvity ?
1 CPU
2 Operating system
3 Control unit
4 Application Program
Right Ans ) 2

7) Virtual memory is __________.
1 An extremely large main memory
2 An extremely large secondary memory
3 An illusion of extremely large main memory
4 A type of memory used in super computers.
Right Ans ) 3

8) The kernel keeps track of the state of each task by using a data structure called __
1 Process control block
2 User control block
3 Memory control block
4 None of the above
Right Ans ) 1

9) Which of the following disk scheduling techniques has a drawback of starvation ?
1 SCAN
2 SSTF
3 FCFS
4 LIFO
Right Ans ) 2

10) A binary semaphore
1 has the values one or zero
2 is essential to binary computers
3 is used only for synchronisation
4 is used only for mutual exclusion
Right Ans ) 1

11) _________ page replacement alogorithm suffers from Belady's anamoly.
1 LRU
2 MRU
3 FIFO
4 LIFO
Right Ans ) 3

12) _________ is a high speed cache used to hold recently referenced page table entries a part of paged virtual memory
1 Translation Lookaside buffer
2 Inverse page table
3 Segmented page table
4 All the above
Right Ans ) 1

13) _________ does the job of allocating a process to the processor.
1 Long term scheduler
2 Short term scheduler
3 Medium term scheduler
4 Dispatcher
Right Ans ) 4

14) In interactive environments such as time-sharing systems, the primary requirement is to provide reasonably good response time and in general, to share system resources equitably. In such situations, the scheduling algorithm that is most popularly applied is ________.
1 Shortest Remaining Time Next (SRTN) Scheduling
2 Priority Based Preemptive Scheduling
3 Round Robin Scheduling
4 None of the above
Right Ans ) 3

15) In the multi-programming environment, the main memory consisting of _________ number of process.
1 Greater than 100
2 Only one
3 Greater than 50
4 More than one
Right Ans ) 4

16) In a multithreaded environment _______.
1 Each thread is allocated with new memory from main memory.
2 Main thread terminates after the termination of child threads.
3 Every process can have only one thread.
4 None of the above
Right Ans ) 2

17) Which of the following statement is not true?
1 Multiprogramming implies multitasking
2 Multi-user does not imply multiprocessing
3 Multitasking does not imply multiprocessing
4 Multithreading implies multi-user
Right Ans ) 4

18) In one of the deadlock prevention methods, impose a total ordering of all resource types, and require that each process requests resources in an increasing order of enumeration. This voilates the _______________ condition of deadlock
1 Mutual exclusion
2 Hold and Wait
3 Circular Wait
4 No Preemption
Right Ans ) 3

19) In the ___________ method of data transfer, the participation of the processor is eliminated during data transfer.
1 Buffering
2 Caching
3 Direct Memory Access
4 Indirect Memory Access
Right Ans ) 3

20) A thread is a __________ process .
1 Heavy Weight
2 Mutliprocess
3 Inter Thread
4 Light wieght
Right Ans ) 4

21) Data reside in file on disk under DOS environment, which of the following file name is invalid ?
1 OSCONCEPTS.doc
2 RAW
3 COMPAQ.BOOK
4 JUMPSTART.BOS
Right Ans ) 3

22) In Priority Scheduling a priority number (integer) is associated with each process. The CPU is allocated to the process with the highest priority (smallest integer = highest priority). The problem of, Starvation ? low priority processes may never execute, is resolved by __________.
1 Terminating the process.
2 Aging
3 Mutual Exclusion
4 Semaphore
Right Ans ) 2

23) CPU Scheduling is the basis of _________ operating system
1 Batch
2 Real time
3 Multiprogramming
4 Monoprogramming
Right Ans ) 3

24) A major problem with priority scheduling is _________.
1 Definite blocking
2 Starvation
3 Low priority
4 None of the above
Right Ans ) 2

25) ________ scheduler selects the jobs from the pool of jobs and loads into the ready queue.
1 Long term
2 Short term
3 Medium term
4 None of the above
Right Ans ) 1

26) Which directory implementation is used in most Operating System?
1 Single level directory structure
2 Two level directory structure
3 Tree directory structure
4 Acyclic directory structure
Right Ans ) 3

27) Saving the state of the old process and loading the saved state of the new process is called ________.
1 Context Switch
2 State
3 Multi programming
4 None of the above
Right Ans ) 1

28) The term " Operating System " means ________.
1 A set of programs which controls computer working
2 The way a computer operator works
3 Conversion of high-level language in to machine level language
4 The way a floppy disk drive operates
Right Ans ) 1

29) Resource locking ________.
1 Allows multiple tasks to simultaneously use resource
2 Forces only one task to use any resource at any time
3 Can easily cause a dead lock condition
4 Is not used for disk drives
Right Ans ) 2

30) A thread
1 is a lightweight process where the context switching is low
2 is a lightweight process where the context swithching is high
3 is used to speed up paging
4 none of the above
Right Ans ) 1

----> NEXT PART ---->

Multiple Choice Questions On Operating System Part-5

1) Using Priority Scheduling algorithm, find the average waiting time for the following set of processes given with their priorities in the order: Process : Burst Time : Priority respectively . P1 : 10 : 3 , P2 : 1 : 1 , P3 : 2 : 4 , P4 : 1 : 5 , P5 : 5 : 2.
1 8 milliseconds
2 8.2 milliseconds
3 7.75 milliseconds
4 3 milliseconds
Right Ans ) 2

2) Routine is not loaded until it is called. All routines are kept on disk in a relocatable load format. The main program is loaded into memory & is executed. This type of loading is called _________
1 Static loading
2 Dynamic loading
3 Dynamic linking
4 Overlays
Right Ans ) 3

3) In the running state
1 only the process which has control of the processor is found
2 all the processes waiting for I/O to be completed are found
3 all the processes waiting for the processor are found
4 none of the above
Right Ans ) 1

4) The Purpose of Co-operating Process is __________.
1 Information Sharing
2 Convenience
3 Computation Speed-Up
4 All of the above
Right Ans ) 4

5) The kernel of the operating system remains in the primary memory because ________.
1 It is mostly called (used)
2 It manages all interrupt calls
3 It controls all operations in process
4 It is low level
Right Ans ) 1

6) The process related to process control, file management, device management, information about system and communication that is requested by any higher level language can be performed by __________.
1 Editors
2 Compilers
3 System Call
4 Caching
Right Ans ) 3

7) Which of the following disk scheduling techniques has a drawback of starvation ?
1 SCAN
2 SSTF
3 FCFS
4 LIFO
Right Ans ) 2

8) Multiprogramming systems ________.
1 Are easier to develop than single programming systems
2 Execute each job faster
3 Execute more jobs in the same time
4 Are used only on large main frame computers
Right Ans ) 3

9) Under multiprogramming, turnaround time for short jobs is usually ________ and that for long jobs is slightly ___________.
1 Lengthened; Shortened
2 Shortened; Lengthened
3 Shortened; Shortened
4 Shortened; Unchanged
Right Ans ) 2

10) Multiprocessing ________.
1 Make the operating system simpler
2 Allows multiple processes to run simultaneously
3 Is completely understood by all major computer vendors
4 Allows the same computer to have the multiple processors
Right Ans ) 4

11) Which is not the state of the process ?
1 Blocked
2 Running
3 Ready
4 Privileged
Right Ans ) 4

12) A set of resources' allocations such that the system can allocate resources to each process in some order, and still avoid a deadlock is called ________.
1 Unsafe state
2 Safe state
3 Starvation
4 Greeedy allocation
Right Ans ) 2

13) The principle of locality of reference justifies the use of ________.
1 Virtual Memory
2 Interrupts
3 Main memory
4 Cache memory
Right Ans ) 4

14) What is the first step in performing an operating system upgrade ?
1 Partition the drive
2 Format the drive
3 Backup critical data
4 Backup old operating system
Right Ans ) 3

15) The technique, for sharing the time of a computer among several jobs, which switches jobs so rapidly such that each job appears to have the computer to itself, is called ________.
1 Time Sharing
2 Time out
3 Time domain
4 Multitasking
Right Ans ) 1

16) In a virtural memory environment
1 segmentation and page tables are stored in the cache and do not add any substantial overhead
2 slow down the computer system considerable
3 segmentation and page tables are stored in the RAM
4 none of the above
Right Ans ) 3

17) If all page frames are initially empty, and a process is allocated 3 page frames in real memory and references its pages in the order 1 2 3 2 4 5 2 3 2 4 1 and the page replacement is FIFO, the total number of page faults caused by the process will be __________.
1 10
2 7
3 8
4 9
Right Ans ) 4

18) Situations where two or more processes are reading or writing some shared data and the final results depends on the order of usage of the shared data, are called ________.
1 Race conditions
2 Critical section
3 Mutual exclusion
4 Dead locks
Right Ans ) 1

19) When two or more processes attempt to access the same resource a _________ occurs.
1 Critical section
2 Fight
3 Communication problem
4 Race condition
Right Ans ) 4

20) Which technique was introduced because a single job could not keep both the CPU and the I/O devices busy?
1 Time-sharing
2 SPOOLing
3 Preemptive scheduling
4 Multiprogramming
Right Ans ) 4

21) _________ allocates the largest hole (free fragmant) available in the memory.
1 Best Fit
2 Worst Fit
3 First Fit
4 None of the above
Right Ans ) 2

22) A process is starved
1 if it is permanently waiting for a resource
2 if semaphores are not used
3 if a queue is not used for scheduling
4 if demand paging is not properly implemented
Right Ans ) 1

23) The degree of Multiprogramming is controlled by
1 CPU Scheduler
2 Context Switching
3 Long-term Scheduler
4 Medium term Scheduler
Right Ans ) 3

24) The time taken to bring the desired track/cylinder under the head is _________.
1 Seek time
2 Latency time
3 Transfer time
4 Read time
Right Ans ) 1

25) Replace the page that will not be used for the longest period of time. This principle is adopted by ____________.
1 FIFO Page replacement algorithm
2 Optimal Page replacement algorithm
3 Round robin scheduling algorithm
4 SCAN scheduling algorithm
Right Ans ) 3

26) Which of the following is a criterion to evaluate a scheduling algorithm?
1 CPU Utilization: Keep CPU utilization as high as possible.
2 Throughput: number of processes completed per unit time.
3 Waiting Time: Amount of time spent ready to run but not running.
4 All of the above
Right Ans ) 4

27) The operating system of a computer serves as a software interface between the user and the ________.
1 Hardware
2 Peripheral
3 Memory
4 Screen
Right Ans ) 1

28) Super computers typically employ _______.
1 Real time Operating system
2 Multiprocessors OS
3 desktop OS
4 None of the above
Right Ans ) 2

29) A process that is based on IPC mechanism which executes on different systems and can communicate with other processes using message based communication, is called ________.
1 Local Procedure Call
2 Inter Process Communication
3 Remote Procedure Call
4 Remote Machine Invocation
Right Ans ) 3

30) A process is
1 program in execution
2 a concurrent program
3 any sequential program
4 something which prevents deadlock
Right Ans ) 1

---> NEXT PART --->

Multiple Choice Questions On Operating System Part-4

1) Round robin scheduling is essentially the preemptive version of ________.
1 FIFO
2 Shortest job first
3 Shortes remaining
4 Longest time first
Right Ans ) 1

2) A page fault occurs
1 when the page is not in the memory
2 when the page is in the memory
3 when the process enters the blocked state
4 when the process is in the ready state
Right Ans ) 1

3) Which of the following will determine your choice of systems software for your computer ?
1 Is the applications software you want to use compatible with it ?
2 Is it expensive ?
3 Is it compatible with your hardware ?
4 Both 1 and 3
Right Ans ) 4

4) Let S and Q be two semaphores initialized to 1, where P0 and P1 processes the following statements wait(S);wait(Q); ---; signal(S);signal(Q) and wait(Q); wait(S);---;signal(Q);signal(S); respectively. The above situation depicts a _________ .
1 Semaphore
2 Deadlock
3 Signal
4 Interrupt
Right Ans ) 2

5) What is a shell ?
1 It is a hardware component
2 It is a command interpreter
3 It is a part in compiler
4 It is a tool in CPU scheduling
Right Ans ) 2

6) Routine is not loaded until it is called. All routines are kept on disk in a relocatable load format. The main program is loaded into memory & is executed. This type of loading is called _________
1 Static loading
2 Dynamic loading
3 Dynamic linking
4 Overlays
Right Ans ) 3

7) In the blocked state
1 the processes waiting for I/O are found
2 the process which is running is found
3 the processes waiting for the processor are found
4 none of the above
Right Ans ) 1

8) What is the memory from 1K - 640K called ?
1 Extended Memory
2 Normal Memory
3 Low Memory
4 Conventional Memory
Right Ans ) 4

9) Virtual memory is __________.
1 An extremely large main memory
2 An extremely large secondary memory
3 An illusion of extremely large main memory
4 A type of memory used in super computers.
Right Ans ) 3

10) The process related to process control, file management, device management, information about system and communication that is requested by any higher level language can be performed by __________.
1 Editors
2 Compilers
3 System Call
4 Caching
Right Ans ) 3

11) If the Disk head is located initially at 32, find the number of disk moves required with FCFS if the disk queue of I/O blocks requests are 98,37,14,124,65,67.
1 310
2 324
3 315
4 321
Right Ans ) 4

12) Multiprogramming systems ________.
1 Are easier to develop than single programming systems
2 Execute each job faster
3 Execute more jobs in the same time
4 Are used only on large main frame computers
Right Ans ) 3

13) Which is not the state of the process ?
1 Blocked
2 Running
3 Ready
4 Privileged
Right Ans ) 4

14) The solution to Critical Section Problem is : Mutual Exclusion, Progress and Bounded Waiting.
1 The statement is false
2 The statement is true.
3 The statement is contradictory.
4 None of the above
Right Ans ) 2

15) The problem of thrashing is effected scientifically by ________.
1 Program structure
2 Program size
3 Primary storage size
4 None of the above
Right Ans ) 1

16) The state of a process after it encounters an I/O instruction is __________.
1 Ready
2 Blocked/Waiting
3 Idle
4 Running
Right Ans ) 2

17) The number of processes completed per unit time is known as __________.
1 Output
2 Throughput
3 Efficiency
4 Capacity
Right Ans ) 2

18) _________ is the situation in which a process is waiting on another process,which is also waiting on another process ... which is waiting on the first process. None of the processes involved in this circular wait are making progress.
1 Deadlock
2 Starvation
3 Dormant
4 None of the above
Right Ans ) 1

19) Which of the following file name extension suggests that the file is Backup copy of another file ?
1 TXT
2 COM
3 BAS
4 BAK
Right Ans ) 4

20) Which technique was introduced because a single job could not keep both the CPU and the I/O devices busy?
1 Time-sharing
2 SPOOLing
3 Preemptive scheduling
4 Multiprogramming
Right Ans ) 4

21) A critical region
1 is a piece of code which only one process executes at a time
2 is a region prone to deadlock
3 is a piece of code which only a finite number of processes execute
4 is found only in Windows NT operation system
Right Ans ) 1

22) The mechanism that bring a page into memory only when it is needed is called _____________
1 Segmentation
2 Fragmentation
3 Demand Paging
4 Page Replacement
Right Ans ) 3

23) PCB =
1 Program Control Block
2 Process Control Block
3 Process Communication Block
4 None of the above
Right Ans ) 2

24) FIFO scheduling is ________.
1 Preemptive Scheduling
2 Non Preemptive Scheduling
3 Deadline Scheduling
4 Fair share scheduling
Right Ans ) 2

25) Switching the CPU to another Process requires to save state of the old process and loading new process state is called as __________.
1 Process Blocking
2 Context Switch
3 Time Sharing
4 None of the above
Right Ans ) 2

26) Which directory implementation is used in most Operating System?
1 Single level directory structure
2 Two level directory structure
3 Tree directory structure
4 Acyclic directory structure
Right Ans ) 3

27) The Banker¿s algorithm is used
1 to prevent deadlock in operating systems
2 to detect deadlock in operating systems
3 to rectify a deadlocked state
4 none of the above
Right Ans ) 1

28) A thread
1 is a lightweight process where the context switching is low
2 is a lightweight process where the context swithching is high
3 is used to speed up paging
4 none of the above
Right Ans ) 1

29) ______ is a high level abstraction over Semaphore.
1 Shared memory
2 Message passing
3 Monitor
4 Mutual exclusion
Right Ans ) 3

30) A tree sturctured file directory system
1 allows easy storage and retrieval of file names
2 is a much debated unecessary feature
3 is not essential when we have millions of files
4 none of the above
Right Ans ) 1

---> NEXT PART --->

Multiple Choice Questions On Operating System Part-3

1) Routine is not loaded until it is called. All routines are kept on disk in a relocatable load format. The main program is loaded into memory & is executed. This type of loading is called _________
1 Static loading
2 Dynamic loading
3 Dynamic linking
4 Overlays
Ans ) 3

2) Which of the following is crucial time while accessing data on the disk?
1 Seek time
2 Rotational time
3 Transmission time
4 Waiting time
Ans ) 1

3) The host repeatedly checks if the controller is busy until it is not. It is in a loop that status register's busy bit becomes clear. This is called _____________ and a mechanism for the hardware controller to notify the CPU that it is ready is called ___________.
1 Interrupt and Polling
2 Polling and Spooling
3 Polling and Interrupt
4 Deadlock and Starvation
Ans ) 3

4) Unix Operating System is an __________.
1 Time Sharing Operating System
2 Multi-User Operating System
3 Multi-tasking Operating System
4 All the Above
Ans ) 4

5) Which of the following memory allocation scheme suffers from External fragmentation?
1 Segmentation
2 Pure demand paging
3 Swapping
4 Paging
Ans ) 1

6) Information about a process is maintained in a _________.
1 Stack
2 Translation Lookaside Buffer
3 Process Control Block
4 Program Control Block
Ans ) 3

7) Distributed OS works on the ________ principle.
1 File Foundation
2 Single system image
3 Multi system image
4 Networking image
Ans ) 2

8) The problem of fragmentation arises in ________.
1 Static storage allocation
2 Stack allocation storage
3 Stack allocation with dynamic binding
4 Heap allocation
Ans ) 4

9) Which file system does DOS typically use ?
1 FAT16
2 FAT32
3 NTFS
4 WNFS
Ans ) 1

10) The program is known as _________ which interacts with the inner part of called kernel.
1 Compiler
2 Device Driver
3 Protocol
4 Shell
Ans ) 4

11) The time taken by the disk arm to locate the specific address of a sector for getting information is called __________.
1 Rotational Latency
2 Seek Time
3 Search Time
4 Response Time
Ans ) 2

12) Which file system does Windows 95 typically use ?
1 FAT16
2 FAT32
3 NTFS
4 LMFS
Ans ) 2

13) Identify the odd thing in the services of operating system.
1 Accounting
2 Protection
3 Error detection and correction
4 Dead lock handling
Ans ) 3

14) Cryptography technique is used in ________.
1 Polling
2 Job Scheduling
3 Protection
4 File Management
Ans ) 3

15) Which of the following is not advantage of multiprogramming?
1 Increased throughput
2 Shorter response time
3 Decreased operating system overhead
4 Ability to assign priorities to jobs
Ans ) 3

16) In ______ OS, the response time is very critical.
1 Multitasking
2 Batch
3 Online
4 Real-time
Ans ) 4

17) An optimal scheduling algorithm in terms of minimizing the average waiting time of a given set of processes is ________.
1 FCFS scheduling algorithm
2 Round robin scheduling algorithm
3 Shorest job - first scheduling algorithm
4 None of the above
Ans ) 3

18) Real time systems are ________.
1 Primarily used on mainframe computers
2 Used for monitoring events as they occur
3 Used for program development
4 Used for real time interactive users
Ans ) 2

19) Which technique was introduced because a single job could not keep both the CPU and the I/O devices busy?
1 Time-sharing
2 SPOOLing
3 Preemptive scheduling
4 Multiprogramming
Ans ) 4

20) Inter process communication can be done through __________.
1 Mails
2 Messages
3 System calls
4 Traps
Ans ) 2

21) In Priority Scheduling a priority number (integer) is associated with each process. The CPU is allocated to the process with the highest priority (smallest integer = highest priority). The problem of, Starvation ? low priority processes may never execute, is resolved by __________.
1 Terminating the process.
2 Aging
3 Mutual Exclusion
4 Semaphore
Ans ) 2

22) CPU performance is measured through ________.
1 Throughput
2 MHz
3 Flaps
4 None of the above
Ans ) 1

23) PCB =
1 Program Control Block
2 Process Control Block
3 Process Communication Block
4 None of the above
Ans ) 2

24) Software is a program that directs the overall operation of the computer, facilitates its use and interacts with the user. What are the different types of this software ?
1 Operating system
2 Language Compiler
3 Utilities
4 All of the above
Ans ) 4

25) A __________ is a software that manages the time of a microprocessor to ensure that all time critical events are processed as efficiently as possible. This software allows the system activities to be divided into multiple independent elements called tasks.
1 Kernel
2 Shell
3 Processor
4 Device Driver
Ans ) 1

26) The primary job of the operating system of a computer is to ________.
1 Command Resources
2 Manage Resources
3 Provide Utilities
4 Be user friendly
Ans ) 2

27) With the round robin CPU scheduling in a time-shared system ________.
1 Using very large time slice degenerates in to first come first served algorithm
2 Using extremely small time slices improve performance
3 Using extremely small time slices degenerate in to last in first out algorithm
4 Using medium sized time slices leads to shortest request time first algorithm
Ans ) 1

28) Which of the following is a criterion to evaluate a scheduling algorithm?
1 CPU Utilization: Keep CPU utilization as high as possible.
2 Throughput: number of processes completed per unit time.
3 Waiting Time: Amount of time spent ready to run but not running.
4 All of the above
Ans ) 4

29) Which of the following is contained in Process Control Block (PCB)?
1 Process Number
2 List of Open files
3 Memory Limits
4 All of the Above
Ans ) 4

30) Super computers typically employ _______.
1 Real time Operating system
2 Multiprocessors OS
3 desktop OS
4 None of the above
Ans ) 2

---> NEXT PART --->

Multiple Choice Questions On Operating System Part-2

1) Consider the two statements.
(A) A network operating system, the users access remote resources in the same manner as local resource.
(B) In a distributed operating system, the user can access remote resources either by logging into the appropriate remote machine or transferring data from the remote machine to their own machine. Which of the statement is true?
1 A true, B false
2 B true, A false
3 Both A and B false
4 Both A and B true
Ans ) 3

2) Using Priority Scheduling algorithm, find the average waiting time for the following set of processes given with their priorities in the order: Process : Burst Time : Priority respectively .
P1 : 10 : 3 ,
P2 : 1 : 1 ,
P3 : 2 : 4 ,
P4 : 1 : 5 ,
P5 : 5 : 2.
1 8 milliseconds
2 8.2 milliseconds
3 7.75 milliseconds
4 3 milliseconds
Ans ) 2

3) Which of the following will determine your choice of systems software for your computer ?
1 Is the applications software you want to use compatible with it ?
2 Is it expensive ?
3 Is it compatible with your hardware ?
4 Both 1 and 3
Right Ans ) 4
Associate Ans) 4

4) What is a shell ?
1 It is a hardware component
2 It is a command interpreter
3 It is a part in compiler
4 It is a tool in CPU scheduling
Ans ) 2

5) The operating system manages ________.
1 Memory
2 Processor
3 Disk and I/O devices
4 All of the above
Ans ) 4

6) The Hardware mechanism that enables a device to notify the CPU is called __________.
1 Polling
2 Interrupt
3 System Call
4 None of the above
Ans ) 2

7) ___________ begins at the root and follows a path down to the specified file
1 Relative path name
2 Absolute path name
3 Standalone name
4 All of the above
Ans ) 2

8) Process State is a part of
1 Process Control block
2 Inode
3 File Allocation Table
4 None of the above
Ans ) 1

9) Virtual Memory is commonly implemented by __________.
1 Segmentation
2 Swapping
3 Demand Paging
4 None of the above
Ans ) 3

10) Virtual memory is __________.
1 An extremely large main memory
2 An extremely large secondary memory
3 An illusion of extremely large main memory
4 A type of memory used in super computers.
Ans ) 3

11) The kernel keeps track of the state of each task by using a data structure called __
1 Process control block
2 User control block
3 Memory control block
4 None of the above
Ans ) 1

12) A binary semaphore
1 has the values one or zero
2 is essential to binary computers
3 is used only for synchronisation
4 is used only for mutual exclusion
Ans ) 1

13) _________ page replacement alogorithm suffers from Belady's anamoly.
1 LRU
2 MRU
3 FIFO
4 LIFO
Ans ) 3

14) A program at the time of executing is called ________.
1 Dynamic program
2 Static program
3 Binded Program p
4 A Process
Ans ) 4

15) _________ is a high speed cache used to hold recently referenced page table entries a part of paged virtual memory
1 Translation Lookaside buffer
2 Inverse page table
3 Segmented page table
4 All the above
Ans ) 1

16) If you don¿t know which version of MS-DOS you are working with, which command will you use after booting your operating system ?
1 Format command
2 FAT command
3 VER command
4 DISK command
Ans ) 3

17) _______ OS pays more attention on the meeting of the time limits.
1 Distributed
2 Network
3 Real time
4 Online
Ans ) 3

18) A process said to be in ___________ state if it was waiting for an event that will never occur.
1 Safe
2 Unsafe
3 Starvation
4 Dead lock
Ans ) 4

19) The removal of process from active contention of CPU and reintroduce them into memory later is known as ____________.
1 Interrupt
2 Swapping
3 Signal
4 Thread
Ans ) 2

20) The problem of thrashing is effected scientifically by ________.
1 Program structure
2 Program size
3 Primary storage size
4 None of the above
Ans ) 1

21) Paging _________.
1 solves the memory fragmentation problem
2 allows modular programming
3 allows structured programming
4 avoids deadlock
Ans ) 1

22) Real time systems are ________.
1 Primarily used on mainframe computers
2 Used for monitoring events as they occur
3 Used for program development
4 Used for real time interactive users
Ans ) 2

23) A thread is a __________ process .
1 Heavy Weight
2 Mutliprocess
3 Inter Thread
4 Light wieght
Ans ) 4

24) _________ allocates the largest hole (free fragmant) available in the memory.
1 Best Fit
2 Worst Fit
3 First Fit
4 None of the above
Ans ) 2

25) Number of CPU registers in a system depends on ____________.
1 Operating system
2 Computer Architecture
3 Computer Organization
4 None of the above
Ans ) 2

26) A major problem with priority scheduling is _________.
1 Definite blocking
2 Starvation
3 Low priority
4 None of the above
Ans ) 2

27) A ___________ contains information about the file, including ownership, permissions, and location of the file contents.
1 File Control Block (FCB)
2 File
3 Device drivers
4 File system
Ans ) 1

28) Which directory implementation is used in most Operating System?
1 Single level directory structure
2 Two level directory structure
3 Tree directory structure
4 Acyclic directory structure
Ans ) 3

29) The term " Operating System " means ________.
1 A set of programs which controls computer working
2 The way a computer operator works
3 Conversion of high-level language in to machine level language
4 The way a floppy disk drive operates
Ans ) 1

30) The operating system of a computer serves as a software interface between the user and the ________.
1 Hardware
2 Peripheral
3 Memory
4 Screen
Ans ) 1

--> NEXT PART -->

Multiple Choice Questions On Operating System Part-1

30 Objective questions based on OS:-

1) Routine is not loaded until it is called. All routines are kept on disk in a relocatable load format. The main program is loaded into memory & is executed. This type of loading is called _________
1 Static loading
2 Dynamic loading
3 Dynamic linking
4 Overlays
Ans ) 3

2) Which of the following is crucial time while accessing data on the disk?
1 Seek time
2 Rotational time
3 Transmission time
4 Waiting time
Ans ) 1

3) The host repeatedly checks if the controller is busy until it is not. It is in a loop that status register's busy bit becomes clear. This is called _____________ and a mechanism for the hardware controller to notify the CPU that it is ready is called ___________.
1 Interrupt and Polling
2 Polling and Spooling
3 Polling and Interrupt
4 Deadlock and Starvation
Ans ) 3

4) Unix Operating System is an __________.
1 Time Sharing Operating System
2 Multi-User Operating System
3 Multi-tasking Operating System
4 All the Above
Ans ) 4

5) Which of the following memory allocation scheme suffers from External fragmentation?
1 Segmentation
2 Pure demand paging
3 Swapping
4 Paging
Ans ) 1

6) Information about a process is maintained in a _________.
1 Stack
2 Translation Lookaside Buffer
3 Process Control Block
4 Program Control Block
Ans ) 3

7) Distributed OS works on the ________ principle.
1 File Foundation
2 Single system image
3 Multi system image
4 Networking image
Ans ) 2

8) The problem of fragmentation arises in ________.
1 Static storage allocation
2 Stack allocation storage
3 Stack allocation with dynamic binding
4 Heap allocation
Ans ) 4

9) Which file system does DOS typically use ?
1 FAT16
2 FAT32
3 NTFS
4 WNFS
Ans ) 1

10) The program is known as _________ which interacts with the inner part of called kernel.
1 Compiler
2 Device Driver
3 Protocol
4 Shell
Ans ) 4

11) The time taken by the disk arm to locate the specific address of a sector for getting information is called __________.
1 Rotational Latency
2 Seek Time
3 Search Time
4 Response Time
Ans ) 2

12) Which file system does Windows 95 typically use ?
1 FAT16
2 FAT32
3 NTFS
4 LMFS
Ans ) 2

13) Identify the odd thing in the services of operating system.
1 Accounting
2 Protection
3 Error detection and correction
4 Dead lock handling
Ans ) 3

14) Cryptography technique is used in ________.
1 Polling
2 Job Scheduling
3 Protection
4 File Management
Ans ) 3

15) Which of the following is not advantage of multiprogramming?
1 Increased throughput
2 Shorter response time
3 Decreased operating system overhead
4 Ability to assign priorities to jobs
Ans ) 3

16) In ______ OS, the response time is very critical.
1 Multitasking
2 Batch
3 Online
4 Real-time
Ans ) 4

17) An optimal scheduling algorithm in terms of minimizing the average waiting time of a given set of processes is ________.
1 FCFS scheduling algorithm
2 Round robin scheduling algorithm
3 Shorest job - first scheduling algorithm
4 None of the above
Ans ) 3

18) Real time systems are ________.
1 Primarily used on mainframe computers
2 Used for monitoring events as they occur
3 Used for program development
4 Used for real time interactive users
Ans ) 2

19) Which technique was introduced because a single job could not keep both the CPU and the I/O devices busy?
1 Time-sharing
2 SPOOLing
3 Preemptive scheduling
4 Multiprogramming
Ans ) 4

20) Inter process communication can be done through __________.
1 Mails
2 Messages
3 System calls
4 Traps
Ans ) 2

21) In Priority Scheduling a priority number (integer) is associated with each process. The CPU is allocated to the process with the highest priority (smallest integer = highest priority). The problem of, Starvation ? low priority processes may never execute, is resolved by __________.
1 Terminating the process.
2 Aging
3 Mutual Exclusion
4 Semaphore
Ans ) 2

22) CPU performance is measured through ________.
1 Throughput
2 MHz
3 Flaps
4 None of the above
Ans ) 1

23) PCB =
1 Program Control Block
2 Process Control Block
3 Process Communication Block
4 None of the above
Ans ) 2

24) Software is a program that directs the overall operation of the computer, facilitates its use and interacts with the user. What are the different types of this software ?
1 Operating system
2 Language Compiler
3 Utilities
4 All of the above
Ans ) 4

25) A __________ is a software that manages the time of a microprocessor to ensure that all time critical events are processed as efficiently as possible. This software allows the system activities to be divided into multiple independent elements called tasks.
1 Kernel
2 Shell
3 Processor
4 Device Driver
Ans ) 1

26) The primary job of the operating system of a computer is to ________.
1 Command Resources
2 Manage Resources
3 Provide Utilities
4 Be user friendly
Ans ) 2

27) With the round robin CPU scheduling in a time-shared system ________.
1 Using very large time slice degenerates in to first come first served algorithm
2 Using extremely small time slices improve performance
3 Using extremely small time slices degenerate in to last in first out algorithm
4 Using medium sized time slices leads to shortest request time first algorithm
Ans ) 1

28) Which of the following is a criterion to evaluate a scheduling algorithm?
1 CPU Utilization: Keep CPU utilization as high as possible.
2 Throughput: number of processes completed per unit time.
3 Waiting Time: Amount of time spent ready to run but not running.
4 All of the above
Ans ) 4

29) Which of the following is contained in Process Control Block (PCB)?
1 Process Number
2 List of Open files
3 Memory Limits
4 All of the Above
Ans ) 4

30) Super computers typically employ _______.
1 Real time Operating system
2 Multiprocessors OS
3 desktop OS
4 None of the above
Ans ) 2

--> NEXT Part -->

Role of India's youth

• Introduction
• Power of youth
• Role of youth
• Problem
• Conclusion
Introduction
In words of James” Youth is the joy, the little bird that has broken out of the eggs and is eagerly waiting to spread out its wings in the open sky of freedom and hope.”

Power of Youth

Youth is the spring of Life. It is the age of discovery and dreams. India is of largest youth population in the world today. The entire world is eyeing India as a source of technical manpower. They are looking at our youth as a source of talents at low costs for their future super profits. If Indian youth make up their mind and work in close unity with working class people, they can hold the political power in their hands. Indian youth has the power to make our country from developing nation to a developed nation. Is it a dream? No, their dreams take them to stars and galaxies to the far corners of the unknown and some of them like our own Kalpana Chawla pursue their dream, till they realize it and die for it in process.
hopes of youth
The youth hopes for a world free of poverty, unemployment, inequality and exploitation of man by man. A world free of discrimination on the grounds of race, colour, language and gender. A world full of creative challenges and opportunities to conquer them. But let us convert these hopes in reality.

Role of Youth:

The role of youth is of most importance in today’s time. It has underplayed itself in field of politics. It should become aspiring entrepreneur rather than mere workers. It can play a vital role in elimination of terrorism. Young participation is important because youth are the country’s power. Youth recognize problems and can solve them. Youth are strong forces in social movements. They educate children about their rights. They help other young people attain a higher level of Intellectual ability and to become qualified adults.

Problems

Unfortunately no one is bothered to dream any s vision. Martin Luther has said, "I have a Dream" and the dream come largely true. If he had not thought of that dream he would have accomplished nothing in his life. Another problem is its indifferent attitude towards things, situation and politics .The new cool formula of “let the things be “is proving fatal to India’s development .Lack of unity and spirit is the major set back . Its time The youth, the students have to realize their power , their role, their duties and their responsibility and stand up for their rights. Now its time that instead of brain drain we should act like magnets and attract world to India.

Conclusion

India can become a developed nation only if everyone contributes to the best of his or her capacity and ability. Youth is wholly experimental and with the full utilization of the talents of the Youth, India will become a complete Nation. Let us hope for the same.‘Youth is like a fire
It crept forward.
A Spark at first
Growing into a flame
The brightening into a Blaze’.

Alphabetical Paging in Gridview

Alphabetical Paging in Gridview

Mayur

GridView paging feature allow us to display fixed number of records on the page and browse to the next page of records. Although paging is a great feature but sometimes we need to view all the items alphabetically. The idea behind this article is to provide a user with a list of all the alphabets and when the user clicks on a certain alphabet then all the records starting with that alphabet will be populated in the GridView control.

using System;

using System.Data;

using System.Data.SqlClient;

using System.Configuration;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

public partial class _Default : System.Web.UI.Page

{

string constr;

protected void Page_Load(object sender, EventArgs e)

{

if (IsPostBack == false)

{

constr = "SELECT * from emp";

binddata(constr);

}

}

public void binddata(string s)

{

string connectionString = "server=TECH-DA98E1DFBA\\SQLEXPRESS;user id=raji;password=chekuri;database=raji";

SqlConnection con = new SqlConnection(connectionString);

SqlDataAdapter da = new SqlDataAdapter(constr , con);

DataSet ds = new DataSet();

da.Fill(ds);

GridView1.DataSource = ds;

GridView1.DataBind();

}

//The RowCreated event is used to create the list.

// In the event first I check for the footer row.

// Once, the footer row is found I run a loop from 65 to 92 and convert each number into the character representation.

// The number 65 stands for “A”, 66 for “B” and so on till 92 for “Z”. Inside the loop I created LinkButton and set the Text property to the alphabet. Finally, the control is added to the cell collection.

//Creating the Alphabetical List:

//The next task is to create an alphabetical list and display it in the GridView control.

//The best place to display the list is the GridView footer. Let’s check out the code which is used to create the list.

protected void GridView1_RowCreated(object sender, GridViewRowEventArgs e)

{

if (e.Row.RowType == DataControlRowType.Footer)

{

TableCell cell = e.Row.Cells[0];

cell.ColumnSpan = 3;

for (int i = 65; i <= (65 + 25); i++)

{

LinkButton lb = new LinkButton();

lb.Text = Char.ConvertFromUtf32(i) + " ";

lb.CommandArgument = Char.ConvertFromUtf32(i);

lb.CommandName = "AlphaPaging";

cell.Controls.Add(lb);

}

}

}

//Fetching the Records Based on the Alphabet:

//In the last section we created the alphabets and displayed them in the footer of the GridView control.

//The next task is to capture the event generated by the alphabets when we click on them and fetch the results based on the alphabet. The RowCommand event is fired whenever you click on any alphabet.

// Take a look at the RowCommand event below:

protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)

{

if (e.CommandName.Equals("AlphaPaging"))

{

constr = "select * from emp WHERE ename LIKE '" + e.CommandArgument + "%'";

binddata(constr);

}

}

}

 

Android Interview Question and answers

Introduction Android:

Android is an operating system for mobile devices that includes middleware and key applications, and uses a modified version of the Linux kernel. It was initially developed by Android Inc..It allows developers to write managed code in the Java language, controlling the device via Google-developed Java libraries…..
The Android SDK includes a comprehensive set of development tools . These include a debugger, libraries, a handset emulator (based on QEMU), documentation, sample code, and tutorials. Currently supported development platforms include x86-architecture computers running Linux (any modern desktop Linux distribution), Mac OS X 10.4.8 or later, Windows XP or Vista.

Android does not use established Java standards, i.e. Java SE and ME. This prevents compatibility among Java applications written for those platforms and those for the Android platform. Android only reuses the Java language syntax, but does not provide the full-class libraries and APIs bundled with Java SE or ME

What is android?
Android is a stack of software for mobile devices which has Operating System, middleware and some key applications. The application executes within its own process and its own instance of Dalvik Virtual Machine. Many Virtual Machines run efficiently by a DVM device. DVM executes Java language?s byte code which later transforms into .dex format files.

What are the advantages of Android?
The following are the advantages of Android:

* The customer will be benefited from wide range of mobile applications to choose, since the monopoly of wireless carriers like AT&T and Orange will be broken by Google Android.
* Features like weather details, live RSS feeds, opening screen, icon on the opening screen can be customized
* Innovative products like the location-aware services, location of a nearby convenience store etc., are some of the additive facilities in Android.
Components can be reused and replaced by the application framework.
*Optimized DVM for mobile devices
*SQLite enables to store the data in a structured manner.
*Supports GSM telephone and Bluetooth, WiFi, 3G and EDGE technologies
*The development is a combination of a device emulator, debugging tools, memory profiling and plug-in for Eclipse IDE.

Features of Android
 Application framework enabling reuse and replacement of components
 Dalvik virtual machine optimized for mobile devices
 Integrated browser based on the open source WebKit engine
 Optimized graphics powered by a custom 2D graphics library; 3D graphics based on the OpenGL ES 1.0 specification (hardware acceleration optional)
 SQLite for structured data storage
 Media support for common audio, video, and still image formats (MPEG4, H.264, MP3, AAC, AMR, JPG, PNG, GIF)
 GSM Telephony (hardware dependent)
 Bluetooth, EDGE, 3G, and WiFi (hardware dependent)
 Camera, GPS, compass, and accelerometer (hardware dependent)
 Rich development environment including a device emulator, tools for debugging, memory and performance profiling, and a plugin for the Eclipse IDE.

Explain about the exceptions of Android?

The following are the exceptions that are supported by Android
* InflateException : When an error conditions are occurred, this exception is thrown
* Surface.OutOfResourceException: When a surface is not created or resized, this exception is thrown
* SurfaceHolder.BadSurfaceTypeException: This exception is thrown from the lockCanvas() method, when invoked on a Surface whose is SURFACE_TYPE_PUSH_BUFFERS
* WindowManager.BadTokenException: This exception is thrown at the time of trying to add view an invalid WindowManager.LayoutParamstoken.

Describe the APK format.
The APK file is compressed the AndroidManifest.xml file, application code (.dex files), resource files, and other files. A project is compiled into a single .apk file.

What is .apk extension? 
The extension for an Android package file, which typically contains all of the files related to a single Android application. The file itself is a compressed collection of an AndroidManifest.xml file, application code (.dex files), resource files, and other files. A project is compiled into a single .apk file.

What is .dex extension 
Android programs are compiled into .dex (Dalvik Executable) files, which are in turn zipped into a single .apk file on the device. .dex files can be created by automatically translating compiled applications written in the Java programming language

What is an adb ?
Android Debug Bridge, a command-line debugging application shipped with the SDK. It provides tools to browse the device, copy tools on the device, and forward ports for debugging.

What is an Application ?
A collection of one or more activities, services, listeners, and intent receivers. An application has a single manifest, and is compiled into a single .apk file on the device.

What is a Content Provider ?
A class built on ContentProvider that handles content query strings of a specific format to return data in a specific format. See Reading and writing data to a content provider for information on using content providers.

What is a Dalvik ?
The name of Android’s virtual machine. The Dalvik VM is an interpreter-only virtual machine that executes files in the Dalvik Executable (.dex) format, a format that is optimized for efficient storage and memory-mappable execution. The virtual machine is register-based, and it can run classes compiled by a Java language compiler that have been transformed into its native format using the included “dx” tool. The VM runs on top of Posix-compliant operating systems, which it relies on for underlying functionality (such as threading and low level memory management). The Dalvik core class library is intended to provide a familiar development base for those used to programming with Java Standard Edition, but it is geared specifically to the needs of a small mobile device.

What is an DDMS 
Dalvik Debug Monitor Service, a GUI debugging application shipped with the SDK. It provides screen capture, log dump, and process examination capabilities.

What is Drawable? 
A compiled visual resource that can be used as a background, title, or other part of the screen. It is compiled into an android.graphics.drawable subclass.

What is an Intent?
A class (Intent) that contains several fields describing what a caller would like to do. The caller sends this intent to Android’s intent resolver, which looks through the intent filters of all applications to find the activity most suited to handle this intent. Intent fields include the desired action, a category, a data string, the MIME type of the data, a handling class, and other restrictions.

What is an Intent Filter ?
Activities and intent receivers include one or more filters in their manifest to describe what kinds of intents or messages they can handle or want to receive. An intent filter lists a set of requirements, such as data type, action requested, and URI format, that the Intent or message must fulfill. For Activities, Android searches for the Activity with the most closely matching valid match between the Intent and the activity filter. For messages, Android will forward a message to all receivers with matching intent filters.

What is an Intent Receiver? 
An application class that listens for messages broadcast by calling Context.broadcastIntent

What is a Layout resource?
An XML file that describes the layout of an Activity screen.

What is a Manifest ?
An XML file associated with each Application that describes the various activies, intent filters, services, and other items that it exposes.

What is a Resource 
A user-supplied XML, bitmap, or other file, entered into an application build process, which can later be loaded from code. Android can accept resources of many types; see Resources for a full description. Application-defined resources should be stored in the res/ subfolders.

What is a Service ?
A class that runs in the background to perform various persistent actions, such as playing music or monitoring network activity.

What is a Theme ?
A set of properties (text size, background color, and so on) bundled together to define various default display settings. Android provides a few standard themes, listed in R.style (starting with “Theme_”).

What is an URIs? 
Android uses URI strings both for requesting data (e.g., a list of contacts) and for requesting actions (e.g., opening a Web page in a browser). Both are valid URI strings, but have different values. All requests for data must start with the string “content://”. Action strings are valid URIs that can be handled appropriately by applications on the device; for example, a URI starting with “http://” will be handled by the browser.

Can I write code for Android using C/C++?
Yes, but need to use NDK
Android applications are written using the Java programming language. Android includes a set of core libraries that provides most of the functionality available in the core libraries of the Java programming language.
Every Android application runs in its own process, with its own instance of the Dalvik virtual machine. Dalvik has been written so that a device can run multiple VMs efficiently. The Dalvik VM executes files in the Dalvik Executable (.dex) format which is optimized for minimal memory footprint. The VM is register-based, and runs classes compiled by a Java language compiler that have been transformed into the .dex format by the included “dx” tool.
Android only supports applications written using the Java programming language at this time.

What is an action?
A description of something that an Intent sender desires.

What is activity?
A single screen in an application, with supporting Java code.

What is intent?
A class (Intent) describes what a caller desires to do. The caller sends this intent to Android’s intent resolver, which finds the most suitable activity for the intent. E.g. opening a PDF file is an intent, and the Adobe Reader is the suitable activity for this intent.

How is nine-patch image different from a regular bitmap?
It is a resizable bitmap resource that can be used for backgrounds or other images on the device. The NinePatch class permits drawing a bitmap in nine sections. The four corners are unscaled; the four edges are scaled in one axis, and the middle is scaled in both axes.

What languages does Android support for application development?
Android applications are written using the Java programming language.

What is a resource?
A user-supplied XML, bitmap, or other file, injected into the application build process, which can later be loaded from code.

How will you record a phone call in Android? How to get a handle on Audio Stream for a call in Android?
Permissions.PROCESS_OUTGOING_CALLS: Allows an application to monitor, modify, or abort outgoing calls.

What’s the difference between file, class and activity in android? 
File – It is a block of arbitrary information, or resource for storing information. It can be of any type.
Class – Its a compiled form of .Java file . Android finally used this .class files to produce an executable apk
Activity – An activity is the equivalent of a Frame/Window in GUI toolkits. It is not a file or a file type it is just a class that can be extended in Android for loading UI elements on view.

What is a Sticky Intent?
sendStickyBroadcast() performs a sendBroadcast (Intent) that is “sticky,” i.e. the Intent you are sending stays around after the broadcast is complete, so that others can quickly retrieve that data through the return value of registerReceiver (BroadcastReceiver, IntentFilter). In all other ways, this behaves the same as sendBroadcast(Intent).

One example of a sticky broadcast sent via the operating system is ACTION_BATTERY_CHANGED. When you call registerReceiver() for that action — even with a null BroadcastReceiver — you get the Intent that was last broadcast for that action. Hence, you can use this to find the state of the battery without necessarily registering for all future state changes in the battery.

Does Android support the Bluetooth serial port profile?
Yes.

Can an application be started on powerup?
Yes.

How to Remove Desktop icons and Widgets
A. Press and Hold the icon or widget. The phone will vibrate and on the bottom of the phone you will see anoption to remove. While still holding the icon or widget drag it to the remove button. Once remove turns red drop the item and it is gone

Describe a real time scenario where android can be used?
Imagine a situation that you are in a country where no one understands the language you speak and you can not read or write. However, you have mobile phone with you.

With a mobile phone with android, the Google translator translates the data of one language into another language by using XMPP to transmit data. You can type the message in English and select the language which is understood by the citizens of the country in order to reach the message to the citizens.

How to select more than one option from list in android xml file? 
Give an example.
Specify android id, layout height and width as depicted in the following example.

What languages does Android support for application development?
Android applications are written using the Java programming language.

Describe Android Application Architecture.
Android Application Architecture has the following components:
• Services – like Network Operation
• Intent – To perform inter-communication between activities or services
• Resource Externalization – such as strings and graphics
• Notification signaling users – light, sound, icon, notification, dialog etc.
• Content Providers – They share data between applications

Common Tricky questions
 Remember that the GUI layer doesn’t request data directly from the web; data is always loaded from a local database.
 The service layer periodically updates the local database.
 What is the risk in blocking the Main thread when performing a lengthy operation such as web access or heavy computation? Application_Not_Responding exception will be thrown which will crash and restart the application.
 Why is List View not recommended to have active components? Clicking on the active text box will pop up the software keyboard but this will resize the list, removing focus from the clicked element.