OPEN SOURCE SOFTWARE
UNIT I : INTRODUCTION
1. What is Open source software?
Open Source Software is software for which the underlying programming
code is available to the users so that they may read it, make changes to it,
and build new versions of the software incorporating their changes. There
are many types of Open Source Software, mainly differing in the licensing
term under which (altered) copies of the source code may (or must be)
redistributed.
2. What is the Need of Open Source Systems?
• No initial cost
• No licensing issues
• Openness and Transparency
• Speed of Access
• Freedom of movement
• Portable
• Reliable
• Stable
• Security
3. What are the four important factors that led to the development of
open source software?
The following are the four important factors that lead to the development of
Open Source Software:
1. To diminish the high monopoly value of the Proprietary Software
2. To avoid discrimination among persons like developers of the
product and users of the product
3. To enable the user finding and fixing the bugs themselves
4. To allow customers to have control over the products they use and
to redistribute the same with or without modifications.
4. What are the advantages of open source system?
• Lesser hardware costs
• High-quality software
• No vendor lock-in
• Integrated management
• Simple license management
• Lower software costs
• Abundant support
• Scaling and consolidating.
5. Mention some Applications of Open Source Systems?
• Finance
• Educational
• Data Storage and Management
• Games
• Media
• Networking and Internet
• Graphics
6. Give some characteristics of Linux?
It is a Unix-like computer operating system.one of the most prominent
examples of free software and open source development: typically all
underlying source code can be freely modified, used, and redistributed by
anyone.The name "Linux" comes from the Linux kernel, started in 1991 by
Linus Torvalds.
Pdominantly known for its use in servers.upported by corporations
such as Dell, Hewlett-Packard, IBM, Novell, Oracle orporation, Red
Hat, and Sun Microsystems sed as an operating system for a wide variety
of computer hardware, including esktop computers, supercomputers, video
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game systems, such as the layStation 2 and PlayStation 3, several arcade
games, and embedded devices uch as mobile phones, routers, wristwatches,
and stage lighting systems
7. What are the two phases in the evolution of Linux?
A Development Phase:
Here the Kernel is not reliable and the Process is to add functionality to it,
Optimize it and to try new ideas. This Phase gives rise to odd-numbered
version
numbers, such as 1.1,1.3 etc., This is the time when the maximum amount of
work is done on the kernel
A Stabilization Phase:
where the aim is to produce as stable a kernel as possible. Only minor
adjustments and modifications are made. The version numbers of so called
Stable Kernels are even, such as 1.0,1.2 etc.,
8. What are the advantages of Linux?
• Low-Cost
• Runs on old Hardware
• Choice
• Installation and GUI
• Security
• Open source
9. List the disadvantages of Linux
• Learning
• Lack of equivalent programs
• More technical ability needed
• Not all hardware compatible
10. What are the types of system?
Operating system is a generic term which in fact describes several families
of systems
Single task system: Only one program may be run at a time, and therefore
only one person may work on a machine at one time. However, the process
may make use of the whole of the resources and power of the machine
Multi task system: Several Processes can be executed in parallel. Operating
time is cut up into small intervals and each process is executed during these
short periods.
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11. What are the roles of an operating system?
• Virtual Machine:
• Sharing the Processor:
• Memory Management:
• Resource management:
• Communication hub of the machine:
12. Define Kernel mode and user mode
The kernel is a privileged mode, in which no restriction is imposed on the
kernel of the system. The kernel may use all the instructions of the
processor, manipulate the whole of the memory, and talk directly to the
peripheral controllers. The user mode is the normal execution mode for a
process. In this mode, the process has no privilege.
13. Define Process and differentiate process and program
A process can be considered to be a program being run. A program is not a
process of itself; it is a passive entity while the process is a active entity with
a program counter specifying the next instruction to be carries out, as well as
the total associated resource.
14. What are the Process states?
During the course of execution, processes change state. The state of a
process is defined by its current activity. The different possible states of a
process are the following
In execution: the process is being executed by the processor,
Ready: the process could be executed, but another process is currently being
executed
Suspended: the process is waiting for a resource
Stopped: the process has been suspended by the external process
Zombie: the process has finished its execution but it is still referenced in the
system
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15. Draw the process state diagram
16. What are the attributes of the process?
During execution, a process is characterized by several attributes maintained
by the system:
• Its state
• Its identification
• The values of the registers, including the program counter
• The user identity whose name the process is executing
• The information used by the kernel to establish the schedule of the
processes
• Information concerning the address space of the process
• Information concerning the inputs/outputs carried out by the process
• Compatibility information summarizing the resources used by the process
17. What are the types of Process Identifiers
• Identification of the real user
• Identification of the effective user
• Identification of the real group
• Identification of the effective group
• A list of group identifiers
18. Define session
A session is a collection of one or more groups of processes. Each session is
assigned to a single control terminal. This terminal is either a peripheral
device or a pseudo-device
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19. Define Scheduler
The scheduler is the kernel function which decides which process should be
executed by the processor: the scheduler scans the list of processes in the
‘ready’ tate, and uses several criteria to choose which process to execute.
20. What are the different scheduling policies in Linux
The Linux scheduler has three different scheduling policies: one for
‘normal’ Processes, and two for ‘real time’ processes
_ SCHED_FIFO, for a unalterable ‘real time’ process.
_ SCHED_RR, for an alterable ‘real time’ process,
_ SCHED_OTHER, for a ‘classical’ process.
21. Define Personality
In order to allow programs coming from other operating system to be run in
Linux, Linux supports the idea of personalities. Each process is assigned to
an execution domain. This domain specifies the way in which system calls
are carried out, and the way in which messages are processed.
22. What a personality defines?
• System calls: Linux uses software interrupts to change into kernel mode,
whilst other Unix system use an inter- segment jump.
• Message number specified by processes: When a process specifies a
message number, for example in calling the primitive sigaction or kill, the
message number is converted by means of look-up-table
• Number of messages sent to processes: when a message is to be sent to a
Process, the message number is converted by means of look-up-table.
23. What is the system call available to change the personality?
The system call personality allows a process to modify its execution domain
in order hat Linux can emulate the behavior of another operating system.
int personality(int pers);
24. Define Clone process
A clone process is created, using primitive type clone, by duplicating its
parent process. But, unlike classical processes, it may share its context with
its parent.
25. Give the system call for cloning
The standard form of the clone function is as follows:
int clone(int (*fn)(), void *child stack, int flag, int nargs,…);
The parameter fn is the pointer from the child process to the function to be
executed.The parameter child_stack is the pointer to the zone of memory
allocated for thestack of child process.
The parameter Flags defines method for cloning
The parameter Nargs defines the number of arguments to be passed to the
functionpointed by fn and is followed by these arguments
26. Define Signal
It allows processes to react to events triggered by themselves, or by other
processes.Each signal corresponds to a particular event.A signal is
represented in the system by a name of the form SIGXX.The total number of
signals existing in the system is marked by the constant NSIGdefined in the
header file <signal.h>
27. What are the ways in which signal can be generated?
A signal may be generated in several ways, such as:
The signal is the result of particular physical circumstance: When a process
writes to a non allocated zone of memory , there is an invalid access to a
page of memory, which raise a flag. This flag is recognized in the kernel,
whichgenerates a SIGSEGV signal which in turn is sent to the process at
fault. It is the result of terminal user typing CTRL-C. This generates the
signal SIGINTfor which the default action is to terminate the process in the
session foreground. It is the result of system call kill or of command of the
same name which allows the signal to be sent to a selected process.
It is the result of event under the control of the kernel.
28. What are the various actions a process may take upon receiving a
signal?
There are various actions a process may take upon receiving a signal, and
three different defaults:
ignore the signal:
terminate the program;
terminate the program and generate a file core
.
29. What are the list of signal available?
• Terminating and suspending Process
• Physical circumstances
• Available for the Programmer
• Signal Generated by system when Pipe is closed
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• Control of activity
• Linked to the resource
• Management of input and output
• Fault in power supply
30. What is the system call available to send a signal?
The system call Kill is used to send a signal to a process or a group of
processes.
int kill( pid_t pid, int sig);
This returns 0 on no error and -1 on error
Sig- signal t be sent
Pid - identity of the receiving entity
If pid=positive, the signal sig is sent to the process identified by pid
If pid=NULL, the signal sig is sent to the sender group of the sender
If pid=-1 the signal sig is sent to all process except the first
If pid<-1 the signal sig is sent to a group of process identified by pid
To sent a signal to group of processes, there is also the call killpg
int killpg(int pgrp, int sig)
This returns null if it is sent to the group
Pgrp- represents the group the signal is sent to.
To sent signal to itself
int raise(int sig);- in the event of error it sends a non zero value
31. List some of the GNU tools
• gcc ,Debugger,Strace and Make
32. What are the formats supported in Linux for executable programs
Linux supports two formats for executable programs
a.out-binary format
ELF – dynamic libraries
33. Define Library and its types
Libraries constitute a simple meaning of gathering several object files
together Static: during link editing, the library code is integrated with the
executable code Dynamic: the library code is loaded when program is
executed`
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UNIT II : OPEN SOURCE DATABASE
1. What is MySQL?
MySQL is a relational database management system which has 11 million
installations.
It can be used for both Windows and Linux. Managing database includes
adding, accessing, and processing data in a database.
2. Why do so many organizations use MySQL?
Advantages:
• Highly efficient
• Open source
• Highly secured since All password traffic is encrypted connecting to a
server.
• Offers a high scalability in terms of size and connectivity.
3. What is "mysqld"?
mysqld is a daemon server program typically used to start and stop mysql
server. It runs in the background
4. How can you connect to the MySQL Server?
In order to connect to the MySQL server, it is required to give the username
and password. So this can be done with the following
% mysql –h localhost –p –u root
-h localhost to connect to the MySQL server running on the local host
-p to tell mysql to prompt for a password
-u root to connect as the MySQL root user
5. How can you Start MySQL Server?
To start the mysql program type its name in the command- line prompt.
After starting themysql program just display a welcome message using the
following Syntax:
% mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 18427 to server version: 3.23.51-log
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql>
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6. How can you terminate the MySQL Server?
Typing the following in Command prompt will shut down the server
completely as root
user
% mysqladmin -u root -p shutdown
7. Explain the tools that are available for managing MySQL Server.
Following are the tools to manage MySQL server:
• mysqld - MySQL server daemon. It is used to start the mysql server.
• mysqladmin – Used to perform administrative tasks.
• mysql - A command-line interface for end users to manage user data
objects.
• mysqlcheck - A command-line interface for administrators to check and
repair tables.
• mysqlshow - A command-line interface for end users to see information
on tables and columns.
• mysqldump - A command-line interface for administrators or end users to
export data from the server to files.
• mysqlimport - A command-line interface for administrators or end users
to load data files into tables program tool to load data into tables.
8. What are the capabilities provided by MySQL client APIs?
• Connecting to the MySQL server; selecting a database; disconnecting
from the server.
• Checking for errors.
• Issuing queries and retrieving results.
• Using prepared statements and placeholders in queries.
• Including special characters and NULL values in queries.
• Handling NULL values in result sets.
9. What are the three fundamental operations that are common to
MySQLPrograms?
• Establishing a connection to the MySQL server.
• Selecting a database.
• Disconnecting from the server
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10. What is difference between mysql_connect and mysql_pconnect?
Mysql_connect() opens a new connection to the database while
mysql_pconnect() opens a persistent connection to the database. This means
that each time the page is loaded
mysql_pconnect() does not open the database. Mysql_close() cannot be used
to close the persistent connection. Though it can be used to close
mysql_connect().
11. What are the two ways in which Warnings can be suppressed in
PHP?
• First, to prevent an individual function call from producing an error
message, put the @ warning suppression operator in front of its name.
• Disable these warnings globally by using the error_reporting( ) function to
set the PHP error level to zero: error_reporting(0)
12. What are the categories of SQL Statements?
• Statements that do not return a result set. This statement category includes
INSERT, DELETE, and UPDATE.
• Statements that return a result set, such as SELECT, SHOW, EXPLAIN,
and DESCRIBE.
13. What are the differences between MySQL_fetch_array(),
MySQL_fetch_object(), MySQL_fetch_row()?
Mysql_fetch_object returns the result from the database as objects while
mysql_fetch_array returns result as an array. This will allow access to the
data by the field names. E.g. using mysql_fetch_object field can be accessed
as $result->name and using mysql_fetch_array field can be accessed as
$result->[name].
mysql_fetch_row($result):- where $result is the result resource returned
from a successful query executed using the mysql_query() function.
Example:
$result = mysql_query(―SELECT * from students);
while($row = mysql_fetch_row($result))
{
Some statement;
}
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14. What are the two types of methods for retrieving rows in Python?
• Fetchone()- Returns the next row as a sequence
• Fetchall()- Returns the entire result set as a sequence of sequences
15. What are the benefits of prepared statements and placeholders
Parameter binding operations automatically handle escaping of characters
Encourage Statement reuse
Easier to read
16. What are the ways of obtaining the connection parameters?
• Hardwire the parameters into the program.
• Ask for the parameters interactively.
• Get the parameters from the command line.
• Get the parameters from the execution environment.
• Get the parameters from a separate file.
• Use a combination of methods.
17. What are the various ways in which SELECT statement can be used
for record selection Technology?
SELECT gives you control over several aspects of record retrieval:
• Which table to use
• Which columns to display from the table
• What names to give the columns
• Which rows to retrieve from the table
• How to sort the rows
18. What is the keyword which can be used to combine column values?
Give Eg.
Column values may be combined to produce composite output values using
the CONCAT () Keyword.
19. How can you map NULL values to other values while display?
IF( ) and IFNULL( ) keywords are used to do so. They are especially useful
for catching divide-by-zero operations and mapping them onto something
else.
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20. When the LIMIT clause will be used?
LIMIT is used for the following kinds of problems:
1)Answering questions about first or last, largest or smallest
2) Splitting a result set into sections so that you can process it one piece at a
time.
21. What are the advantages of copying records from one table to
another?
1.When an algorithm that modifies a table is used then it is safer to work
with the copy
2.When the original table is large then it takes large time to work with so it
is better to work with the which takes less time
3.The data-loading operations that may be malformed when used with
original table can go with the copy to ensure safety
4.The summary operations when repeatedly done over the original table are
expensive so copy can be used to print the summary which is not
expensive as original table
22. What is the use of creating such tables? How can you create
temporary tables?
When you need a table only for a short time, then you want it to disappear
Automatically you can go to create a temporary table. This is extremely
useful behavior because you need not remember to remove the table
The Temporary tables can be created using the keyword CREATE
TEMPORARY TABLE
23. What are the disadvantages of creating a temporary table?
• If you've already created a temporary table with a given name, attempting
to create a second one with that name results in an error.
• persistent connections – may tend not to drop the temporary table
because the connection is let open for the use of next script
• If a client program automatically reconnects after a dropped connection,
you'll be modifying the original table after the reconnect
24. What are the properties of Strings?
• Strings can be case sensitive (or not), which can affect the outcome of
string operations.
• You can compare entire strings, or just parts of them by extracting
substrings.
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• You can apply pattern-matching operations to look for strings that have a
certain structure.
25. What are the types of Strings?
• A binary string in MySQL is one that MySQL treats as case sensitive in
comparisons.
• A non binary string in MySQL is one that MySQL does not treats as case
sensitive in comparisons.
• For binary strings, the characters A and a are considered different. For
non-binary strings, they're considered the same.
26. Does the MID() acts the same way as SUBSTRING() ? Justify
MID() acts the same way as the SUBSTRING() if the third argument of the
MID() is omitted.
27. What are the ways provided by MySQL for Pattern Matching?
MySQL provides two kinds of pattern matching.
1) One is based on SQL patterns
2) regular expressions.
28. What are the data types supported by MySQL for Date and Time
formats?
MySQL supports a number of date and time column formats: Some of
them are
DATE
DATETIME
TIMESTAMP
29. Give Examples of various type of Date and Time formats.
It is most common to store dates using a dash (-) as the delimiter and a colon
(:)
as the time delimiter. The Following formats can also be used.
2008-10-23 10:37:22
20081023103722
2008/10/23 10.37.22
2008*10*23*10*37*22
30. Why do you go for sorting your query results?
SQL SELECT command to fetch data from MySQL table. When you select
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rows, the MySQL server is free to return them in any order, unless you
instruct it otherwise by saying how to sort the result. But you sort a result set
by adding an ORDER BY clause that names the column or columns you
want to sort by.
31. Define Aggregate functions and what are aggregate functions
supported by the MySQL
To compute a summary value from a set of individual values, use one of the
functions known as aggregate functions. These are so called because they
operate on aggregates (groups) of values.
Aggregate functions include COUNT( ), which counts records or values in a
query result; MIN( ) and MAX( ), which find smallest and largest values;
and SUM( ) and AVG( ), which produce sums and means of values.
32. What are the types of information available in MySQL?
Information about the result of queries: This includes number of records
effected by any SELECT, UPDATE or DELETE statement.
Information about tables and databases: This includes information
pertaining to the structure of tables and databases.
Information about the MySQL server: This includes current status of
database server, version number etc
33. Define Sequence
A sequence is a set of integers 1, 2, 3, ... that are generated in order on
demand. Sequences are frequently used in databases because many
applications require each row in a table to contain a unique value, and
sequences provide an easy way to generate them
UNIT III : OPEN SOURCE PROGRAMMING LANGUAGES
1. What is PHP?
_ PHP stands for Hypertext Preprocessor and is a server-side language.
_ This means that when a visitor opens the page, the server processes the
PHP commands and then sends the results to the visitor's browser, just as
with ASP.
_ A typical PHP files will content commands to be executed in the server in
addition to the usual mixture of text and HTML (Hypertext Markup
Language)tags. However, PHP is Open Source and cross-platform.
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2. What can PHP do for you?
PHP offers plenty of possibilities:
_ PHP is appropriate whenever you want your pages to be created
dynamically when the browser requests the page. For example, you can
display date, time, and other information in different ways. PHP will make
your website more dynamic in content and a heck of a lot easier to update.
_ PHP makes it easy to customize a Web page to make it more useful for
individual users.
_ With PHP you can set cookies, manage authentication, and redirect users.
_ One of PHP most powerful features is database access. With PHP it is
possible to access over 19 different types of databases and manipulate data
within those databases based on input from the user via a web page.
_ PHP makes it easy to send e-mail, work with newsgroups, and actually
open a connection to another web site -- and get or send data with it. If you
are already familiar with ASP development, PHP can also communicate with
other serverside languages such as Java and use COM interfaces.
3. Define Variable.
_ A variable is a holder for a type of data. So, based on its type, a variable
can hold numbers, strings, booleans, objects, resources or it can be NULL.
_ In PHP all the variables begin with a dollar sign "$" and the value can be
assignes using the "=" operator.
_ The dollar sign is not technically part of the variable name, but it is
required as the first character for the PHP parser to recognize the variable as
such.
4. What are the variable naming conventions in PHP?
_ There are a few rules that you need to follow when choosing a name for
your PHP variables.
_ PHP variables must start with a letter or underscore "_".
_ PHP variables may only be comprised of alpha-numeric characters and
underscores. a-z, A-Z, 0-9, or _ .
_ Variables with more than one word should be separated with underscores:
$my_variable.
_ Variables with more than one word can also be distinguished with
capitalization:
$myVariable.
_ One important thing to note if you are coming from another programming
language there is no size limit for variables.
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5. What are the scope of variables in PHP?
_ The scope of a variable, which is controlled by the location of the
variable’s declaration, determines those parts of the program that can access
it. There are four types of variable scope in PHP:
_ Local - A variable declared in a function is local to that function.
_ global - Variables declared outside a function are global. That is, they can
be accessed from any part of the program.
_ Static - A static variable retains its value between calls to a function but is
visible only within that function.
_ function parameters - Function parameters are local, meaning that they
are available only inside their functions.
6. Define constant and what is the main difference between the variable
and the constant
_ Constants just as variables are used to store information.
_ The main difference between constants and variables is that constant value
can not be changed in the process of running program.
7. What are the data types available in PHP?
_ PHP provides eight types of values, or data types.
_ Four are scalar (single-value) types:
• integers,
• floating-point numbers,
• strings, and
• booleans.
_ Two are compound (collection) types:
• arrays and
• objects.
_ The remaining two are special types:
• resource and
• NULL.
8. Define expressions and operators.
_ An expression is a bit of PHP that can be evaluated to produce a value.
The simplest expressions are literal values and variables.
_ A literal value evaluates to itself, while a variable evaluates to the value
stored in the variable. More complex expressions can be formed using
simple expressions and operators.
_ An operator takes some values (the operands) and does something (for
instance, adds them together).
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9. What are the different types of Operators based on the number of
operands it takes?
_ Most operators in PHP are binary operators; they combine two operands
(or expressions) into a single, more complex expression.
_ PHP also supports a number of unary operators, which convert a single
expression into a more complex expression.
_ Finally, PHP supports a single ternary operator that combines three
expressions into a single expression.
10. Define Operator Precedence ,operator associativity and casting
_ The order in which operators in an expression are evaluated depends on
their relative precedence.
_ Associativity defines the order in which operators with the same order of
precedence are evaluated.
_ The conversion of a value from one type to another is called casting.
11. What are the types of operators available in PHP?
_ The conversion of a value from one type to another is called casting.
• Arithmetic Operators
• String Concatenation Operator
• Auto increment and Auto decrement Operators
• Comparison Operators
• Bitwise Operators
• Logical Operators
• Casting Operators
• Assignment Operators and some miscellaneous Operators
12. What are the flow control statements available in PHP and give the
syntax of each statement?
if
if (expression)
statement
if else
if (expression)
statement
else
statement
switch
switch($name) {
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case 'ktatroe':
// do something
break;
case 'rasmus':
// do something
break;}
while
while (expression)
statement
do/while
do
statement
while (expression)
for
for (start; condition; increment)
statement
foreach
foreach ($array as $current) {
// ...
}
declare
declare (directive)
statement
exit and return
13. Define Function
_ A function is a named block of code that performs a specific task, possibly
acting upon a set of values given to it, or parameters, and possibly returning
a single value.
14. Give the syntax to call a function
_ $some_value = function_name( [ parameter, ... ] );
_
15. Give the syntax to define a function
_ To define a function, use the following syntax:
function [&] function_name ( [ parameter [, ... ] ] )
{
statement list
}
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16. What are the types to pass parameters to the function?
There are two different ways of passing parameters to a function.
– The first, and more common, is by value.
– The other is by reference.
17. Define Passing parameters by values and reference
_ When a parameter is passed by value, the compiler passes the actual value
to the called procedure. When a parameter is passed by value, the called
program or procedure can change the value of the parameter, but the caller
will never see the changed value
_ Passing parameters by reference to a procedure allows the callee to modify
the field passed.
18. What is the Drawback of returning the reference?
_ The drawback of returning the reference is that it is slower than returning
the value and relying on the shallow-copy mechanism to ensure that a copy
of that data is not made unless it is changed.
19. Define array in PHP
_ An array is a special variable, which can store multiple values in one
single variable.
_ Arrays can be used in many ways to store and organize data quickly and
efficiently. It is one of the more useful data types available to any
programming language.
_ Arrays can most easily be described as an ordered list of elements.
20. How can you assign a range of values to the array?
_ The range( ) function creates an array of consecutive integer or character
values between the two values you pass to it as arguments.
For example:
$numbers = range(2, 5); // $numbers = array(2, 3, 4, 5);
$letters = range('a', 'z'); // $letters holds the alphabet
$reversed_numbers = range(5, 2); // $reversed_numbers = array(5, 4, 3, 2);
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21. How can you get the size of the array?
_ The count( ) and sizeof( ) functions are identical in use and effect. They
return the number of elements in the array. There is no stylistic preference
about which function you use.
$family = array('Fred', 'Wilma', 'Pebbles');
$size = count($family); // $size is 3
22. What are the functions available to sort an array?
Sorting numerically indexed arrays
_ The sort() function orders the array element in ascending order.
Sorting associative arrays
_ The asort() function orders the array according to the value of each
element in ascending order.
_ we use ksort() function to sort an associative array according to the key in
ascending order.
Sorting arrays in the reverse order
_ Rsort() function sorts one-dimensional numerically indexed array by the
values in reverse order.
_ Arsort() function sorts one-dimensional associative array by the values in
reverse order.
_ Krsort() function sorts one-dimensional associative array by the keys in
reverse order.
23. What is OOP?
_ OOP stands for Object Oriented Programming. OOP is a programming
paradigm wherein you create "objects" to work with. These objects can then
be tailored to your specific needs, to serve different types of applications
while maintaining the same code base. Quite useful indeed.
24. What is an object and class?
_ An object is simply a copy or instance of a "class".
_ A class can be defined as a "black box" from where we create our objects
and access its attributes (variables) and methods (functions).
25. Define Polymorphism
_ Polymorphism is an OOP characteristic that allows the programmer to
assign a different meaning or usage to something in different contexts -
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specifically, to allow a class member to perform different tasks depending
on the context it was used.
26. Define Inheritance
_ The basic idea behind inheritance is that similar objects share common
properties. So by creating a "generic" class, we can have a blueprint to build
our subsequent classes on.
27. What are the levels of visibility?
_ Public: means that a class member is visible and usable / modifiable by
everyone
_ Private: means that a class member is only usable / modifiable by the
class itself
_ Protected: means that a class member is only usable / modifiable by the
class itself and eventual sub-classes
28. What are the functions available to search a string?
_ strpos() - The way strpos works is it takes some string you want to search
in as its first argument and another string, which is what you are actually
searching for, as the second argument.
$pos = strpos($mystring, $findme);
_ str_replace() - The str_replace function is similar to a word processor's
"Replace All" command
str_replace(search, replace, originalString).
_ substr_replace() - The function substr_replace introduces some additional
functionality to compliment str_replace. substr_replace is a more
mathematically based replace function, which relies on starting points and
lengths to replace parts of strings, as opposed to searching and replacing.
substr_replace(original string, replacement string, starting
point)
29. What are the capitalization functions available in PHP?
_ PHP has three primary capitalization related functions:
• strtoupper
• strtolower and
• ucwords.
_ The function names are pretty self-explanatory
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30. Define Regular Expression and what are the regular expressions
supported by PHP
_ A regular expression is a string that represents a pattern. The regular
expression functions compare that pattern to another string and see if any of
the string matches the pattern.
_ PHP provides support for two different types of regular expressions:
• POSIX
• Perl compatible.
31. What are the three uses of regular expressions
• matching, which can also be used to extract information from a string;
• substituting new text for matching text;
• splitting a string into an array of smaller chunks.
32. What are the three basic types of abstract patterns in a regular
expression?
_ A set of acceptable characters that can appear in the string (e.g.,
alphabetic characters, numeric characters, specific punctuation characters)
_ A set of alternatives for the string (e.g., "com", "edu", "net", or "org")
_ A repeating sequence in the string (e.g., at least one but no more than five
numeric characters)
_ A set of acceptable characters that can appear in the string (e.g.,
alphabetic characters, numeric characters, specific punctuation characters)
_ A set of alternatives for the string (e.g., "com", "edu", "net", or "org")
_ A repeating sequence in the string (e.g., at least one but no more than five
numeric characters)
33. Define anchor and Quantifier
_ An anchor limits a match to a particular location in the string (anchors do
not match actual characters in the target string).
_ The quantifier goes after the pattern that’s repeated and says how many
times to repeat that pattern.
34. Define Greedy and Non greedy quantifier
_ when faced with a quantifier, the engine matches as much as it can while
still satisfying the rest of the pattern.-Greedy
_ Quantifiers that match as few times as possible to satisfy the rest of the
pattern- Non Greedy
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35. What is a file?
_ A file is a sequence of bytes stored persistently on a physical medium like
a hard disk. Each file is uniquely identified by its absolute path.
36. Mention the advantages of simple text file system
1) Minimization of cost. Cost of maintaining databases like Oracle are huge,
thus files are low cost answer to these databases.
2) Taking back Up of your database is very easy. All you have to do is to
copy the file.
3) It much easier to transfer a text file from one OS to another.
37. Mention the disadvantages of simple text file system
1) Text files do not support SQL Query languages. Thus you will have to
code your data retrieval and updation algorithms yourself.
2) It does not use any indexing mechanism , thus searching mechanism is
much slower.
3) You cannot use triggers, define primary keys , Foreign Keys etc.
38. How can you open a file?
_ The fopen() function can be used to open any file in the server's file
system.
int fopen(string filename, string mode [, string use_include_path])
39. How can you close a file?
int fclose(int fp)
_ The fclose() function is used to close an opened file. The argument fp is
the file pointer of the file to be closed.
40. What are the functions available to read a file?
_ string fread(int fp, int length)
_ string fgetc(int fp)
_ string fgets(int fp, int length)
_ string fgetss(int fp, int length [,string allowable_tags])
_ array file(string filename [,int use_include_path])
41. What are the functions available to write contents to a file?
_ int fputs(int fp, string stringtoWrite [,int length]);
_ int fwrite(int fp, string stringtoWrite [,int length]);
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42. What are the functions available to display a file?
_ int fpassthru(int fp)
_ int readfile(string filename)
43. What are the functions available to navigate within a file?
_ int rewind(int fp)
_ int fseek(int fp, int offset [, int whence])
_ int ftell(int fp)
_ int feof(int fp)
44. What are the functions available to copy , rename and delete a file?
_ int copy(string source, string destination)
_ int rename(string oldname, string newname)
_ int unlink(string filename)
45. What are the functions available to determine the attributes of a
file?
_ int file_exists(string filename)
_ int fileatime(string filename)
_ int filectime(string filename)
_ int filemtime(string filename)
_ int filesize(string filename)
_ string filetype(string filename)
46. What are the three places where the data can be stored in PHP?
• flat file
• session variables
• cookies.
47. Define flat files and mention its advantages over databases
_ Flat files are text files stored in the computer file system. Humans can read
flat files by using the operating system commands that display files, such as
cat in Linux and Unix.
_ Flat files have some advantages over databases:
• Available and versatile: You can create and save data in any operating
system's file system. You don't need to install any extra software.
Additionally, text data stored in flat files can be read by a variety of
software programs, such as word processors or spreadsheets.
• Easy to use: You don't need to do any extra preparation, such as install
database software, design a database, create a database, and so on. Just
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create the file and store the data with statements in your PHP script.
• Smaller: Flat files store data by using less disk space than databases.
48. What are the components of LDAP?
_ LDAP data organization, defines how the data is formatted while in
storage and exchange with respect to the communicating LDAP entities, that
is, client-server and server-server
_ LDAP server is the server that LDAP clients interact with to obtain
directory information.
_ LDAP protocol, is the common language spoken by clients and servers
when the clients access the directory
_ LDAP clients implemented using different vendor APIs and tools on
different platforms are able to connect to the LDAP server, as long as they
speak the LDAP protocol and handle data in the particular format required
by LDAP.
49. List out the characteristics of LDAP
_ Global Directory Service
_ Open Standard Interconnectivity
_ Customizability and Extensibility
_ Heterogeneous Data Store
_ Secure and Access Controlled Protocol
50. List out the various models of LDAP
_ Information model
_ Naming model
_ Functional model
_ Security model
51. What are the various PHP's LDAP client functions?
The various PHP's LDAP client functions:
_ Connection and control functions
_ Search functions
_ Modification functions
_ Error functions
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52.What are the different error handling methods in PHP?
The different error handling methods:
• Simple "die()" statements
• Custom errors and error triggers, Error reporting
53. Give the Importance of PHP Seurity
_ PHP is widely used language for web applications
_ PHP is making headway into enterprise as well as corporate markets
_ Most effective and often overlooked measure to prevent malicious users
_ PHP applications often end up working with sensitive data
54. What are the concerns of PHP security?
_ Register Globals
_ SQL Injection
_ Cross Site Scripting
_ User login systems
55. Define Template
A template is an HTML-like document that defines the presentation of a
web page, while a PHP script supplies the content. The separation of content
and presentation is at the heart of any GUI paradigm.
UNIT IV : PYTHON
1. Give some of the rules and certain symbols used with regard to
statements
in Python
Hash mark ( # ) indicates Python comments
NEWLINE ( \n ) is the standard line separator (one statement per line)
Backslash ( \ ) continues a line
Semicolon ( ; ) joins two statements on a line
Colon ( : ) separates a header line from its suite
Statements (code blocks) grouped as suites
Suites delimited via indentation
Python files organized as "modules"
2. Give the module structure and layout of python programming
# (1) startup line (Unix)
# (2) module documentation
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# (3) module imports
# (4) variable declarations
# (5) class declarations
# (6) function declarations
# (7) "main" body
3. Give the characteristics of Python objects
Identity
Unique identifier that differentiates an object from all others.
Type
An object's type indicates
what kind of values an object can hold,
what operations can be applied to such objects, and
what behavioral rules these objects are subject to.
Value
Data item that is represented by an object.
4. What are the standard types present in python programming
Numbers (four separate sub-types)
Regular or "Plain" Integer
Boolean
Long Integer
Floating Point Real Number
Complex Number
String
List
Tuple
Dictionary
5. What are the built in types present in python programming
Some other built in types are
Type
Null object(None)
File
Set/Frozenset
Function/Method
Module
Class
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6. What are the internal types present in python programming
The following internal types are in python programming
Code
Frame
Traceback
Slice
Ellipsis
Xrange
7. What are the types of numbers present in python
Python has four types of numbers:
"plain" integers,
long integers,
floating point real numbers, and
complex numbers.
8. How to Create and Assign Numbers (Number Objects)
Creating numbers is as simple as assigning a value to a variable:
anInt = 1
aLong = -9999999999999999L
aFloat = 3.1415926535897932384626433832795
aComplex = 1.23 + 4.56J
9. How to Update Numbers
You can "update" an existing number by (re)assigning a variable to another
number. The new value can be related to its previous value or to a
completely different number altogether.
anInt = anInt + 1
aFloat = 2.718281828
10. How to Remove Numbers
Under normal circumstances, you do not really "remove" a number; you just
stop using it! If you really want to delete a reference to a number object, just
use the del statement
del anInt
del aLong, aFloat, aComplex
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11. Define sequence
Sequence types all share the same access model: ordered set with
sequentially indexed offsets to get to each element.
The numbering scheme used starts from zero (0) and ends with one less the
length of the sequence.
12. How can you access elements using slice operator?
The syntax for accessing an individual element is:
sequence[index]
The syntax for accessing a group of elements is:
sequence [ [starting_index]: [ending_index]]
13. How to Create and Assign Strings
Creating strings is as simple as assigning a value to a variable:
>>> aString = 'Hello World!'
>>> print aString
Hello World!
>>> aBlankString = ''
>>> print aBlankString
''
14. How to Access Values(Characters and Substrings) in Strings
Python does not support a character type; these are treated as strings of
length one, thus also considered a substring. To access substrings, use the
square brackets for slicing along with the index or indices to obtain your
substring:
>>> aString = 'Hello World!'
>>> aString[0]
'H'
>>> aString[1:5]
'ello'
>>> aString[6:]
'World!'
15. How to Update Strings
You can "update" an existing string by (re)assigning a variable to another
string. The new Value can be related to its previous value or to a completely
different string altogether.
>>> aString = aString[:6] + 'Python!'
>>> aString
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'Hello Python!'
Like numbers, strings are not mutable, so you cannot change an existing
string without creating a new one from scratch. That means that you cannot
update individual characters or substrings in a string.
16. How to Remove Characters and Strings
To repeat what we just said, strings are immutable, so you cannot remove
individual characters from an existing string. What you can do, however, is
to empty the string, or to put together another string which drops the pieces
you were not interested in.
>>> aString = 'Hello World!'
>>> aString = aString[:3] + aString[4:]
>>> aString
'Helo World!'
To clear or remove a string, you assign an empty string or use the del
statement, respectively:
>>> aString = ''
>>> aString
''
>>> del aString
In most applications, strings do not need to be explicitly deleted. Rather, the
code defining the string eventually terminates, and the string is automatically
garbage collected.
17. Define raw string operator
The purpose of raw strings, introduced to Python in version 1.5, is to
counteract the behavior of the special escape characters that occur in strings.
In raw strings, all characters are taken verbatim with no translation to special
or non-printed characters. This feature makes raw strings absolutely
convenient when such behavior is desired, such as when composing regular
expressions
18. How to Create and Assign Lists
Creating lists is as simple as assigning a value to a variable. You handcraft a
list (empty or with elements) and perform the assignment. Lists are
delimited by surrounding square brackets ( [ ] ).
>>> aList = [123, 'abc', 4.56, ['inner', 'list'], 7-9j]
>>> print aList
[123, 'abc', 4.56, ['inner', 'list'], (7-9j)]
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19. How to Access Values in Lists
Slicing works similar to strings; use the square bracket slice operator ( [ ] )
along with the index or indices.
>>> aList[0]
123
>>> aList[:3]
[123, 'abc', 4.56]
>>> aList[3][1]
'list'
20. How to Update Lists
You can update single or multiple elements of lists by giving the slice on the
left-hand side of the assignment operator, and you can add to elements in a
list with the append() method:
>>> aList
[123, 'abc', 4.56, ['inner', 'list'], (7-9j)]
>>> aList[2]
4.56
>>> aList[2] = 'float replacer'
>>> aList
[123, 'abc', 'float replacer', ['inner', 'list'], (7-9j)]
>>>
21. How to Remove List Elements and Lists
To remove a list element, you can use either the del statement if you know
exactly which element(s) you are deleting or the remove() method if you do
not know.
>>> aList
[123, 'abc', 'float replacer', ['inner', 'list'], (7-9j)]
>>> del aList[1]
>>> aList
[123, 'float replacer', ['inner', 'list'], (7-9j)]
>>> aList.remove(123)
>>> aList
22. How to Create and Assign Tuples
Creating and assigning lists are practically identical to lists, with the
exception of empty tuples. These require a trailing comma ( , ) enclosed in
the tuple delimiting parentheses ( ( ) ).
>>> aTuple = (123, 'abc', 4.56, ['inner', 'tuple'], 7-9j)
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>>> print aTuple
(123, 'abc', 4.56, ['inner', 'tuple'], (7-9j))
23. How to Access Values in Tuples
Slicing works similar to lists: Use the square bracket slice operator ([ ])
along with the
index or indices.
>>> aTuple>>> aList[1:4]
('abc', 4.56, ['inner', 'tuple'])
>>> aTuple[:3]
(123, 'abc', 4.56)
>>> aTuple[3][1]
'tuple'
24. How to Update Tuples
Like numbers and strings, tuples are immutable which means you cannot
update them or change values of tuple elements. In Sections 6.2 and 6.3.2,
we were able to take portions of an existing string to create a new string. The
same applies for tuples.
>>> aTuple = aTuple[0], aTuple[1], aTuple[-1]
>>> aTuple
(123, 'abc', (7-9j))
>>> tup1 = (12, 34.56)
>>> tup2 = ('abc', 'xyz')
>>> tup3 = tup1 + tup2
>>> tup3
(12, 34.56, 'abc', 'xyz')
25. How to Remove Tuple Elements and Tuples
Removing individual tuple elements is not possible. There is, of course,
nothing wrong with putting together another tuple with the undesired
elements discarded. To explicitly remove an entire list, just use the del
statement:
del aTuple
26. How to Create and Assign Dictionaries
Creating dictionaries simply involves assigning a dictionary to a variable,
regardless of whether the dictionary has elements or not:
>>> dict1 = {}
>>> dict2 = {'name': 'earth', 'port': 80}
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>>> dict1, dict2
({}, {'port': 80, 'name': 'earth'})
27. How to Access Values in Dictionaries
To access dictionary elements, you use the familiar square brackets along
with the key to obtain its value:
>>> dict2['name']
'earth'
>>>
>>> print 'host %s is running on port %d' % \
... (dict2['name'], dict2['port'])
host earth is running on port 80
28. How to Update Dictionaries
You can update a dictionary by adding a new entry or element (i.e., a key-
value pair), modifying an existing entry, or deleting an existing entry (see
below for more details on removing an entry).
>>> dict2['name'] = 'venus' # update existing entry
>>> dict2['port'] = 6969 # update existing entry
>>> dict2['arch'] = 'sunos5' # add new entry
>>>
>>> print 'host %(name)s is running on port %(port)d' % dict2
host venus is running on port 6969
29. How to Remove Dictionary Elements and Dictionaries
del dict1['name'] # remove entry with key 'name'
dict1.clear() # remove all entries in dict1
del dict1 # delete entire dictionary
30. Define dictionary key look up operator
The only operator specific to dictionaries is the key-lookup operator, which
works very similar to the single element slice operator for sequence types.
For a dictionary, lookups are by key, so that is the argument rather than an
index. The key- lookup operator is used for both assigning values to and
retrieving values from a dictionary:
dict[k] = v # set value 'v' in dictionary with key 'k'
dict[k] # lookup value in dictionary with key 'k'
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31. Define pass statement
One Python statement not found in C is the pass statement.
Because Python does not use curly braces to delimit blocks of code, there
are places where code is syntactically required.
We do not have the equivalent empty braces or single semicolon the way C
has to indicate "do nothing."
If you use a Python statement that expects a sub-block of code or suite, and
one is not present, you will get a syntax error condition.
For this reason, we have pass, a statement that does absolutely nothing—it is
a true NOP, to steal the "No OPeration" assembly code jargon
32. List the file built in methods
File methods come in four different categories:
input
output
movement within a file("intra-file motion") and
miscellaneous
33. DefineCommand line arguments
Command-line arguments are those arguments given to the program in
addition to the script name on invocation. Historically, of course, these
arguments are so named because they are given on the command-line along
with the program name in a textbased environment like a Unix- or DOS-
shell.
34. Define Pickling or flattening or serializing or marshelling
Pickling is the process whereby objects more complex than primitive types
can be converted to a binary set of bytes that can be stored or transmitted
across the network, then be converted back to their original object forms.
Pickling is also known as flattening, serializing, or marshalling.
35. What is the function of DBM- Style module and shelve module
The *db* series of modules writes data in the traditional DBM format
The shelve module uses the anydbm module to find a suitable DBM module,
then uses cPickle to perform the pickling process. The shelve module
permits concurrent read access to the database file, but not shared
read/write access.
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36. Define exception
Exceptions can best be described as action that is taken outside of the normal
flow of control because of errors. This action comes in two distinct phases,
the first being the error which causes an exception to occur, and the second
being the detection (and possible resolution) phase.
37. What are the various types of errors in python
NameError: attempt to access an undeclared variable
ZeroDivisionError: division by any numeric zero
SyntaxError: invalid syntax
IndexError: request for an out-of-range index for sequence
KeyError: request for a non-existent dictionary key
IOError: input/output error
AttributeError: attempt to access an unknown object attribute
38. How to detect and handle errors in python
Exceptions can be detected by incorporating them as part of a try statement.
Any code suite of a try statement will be monitored for exceptions.
There are two main forms of the try statement: try-except and try-finally.
try-except statements allow one to detect and handle exceptions.
try-finally statements allow only for detection and processing of any
obligatory clean-up
39. Differentiate function and procedure
Functions are often compared to procedures. Both are entities which can be
invoked, but the traditional function or "black box," perhaps taking some or
no input parameters, performs some amount of processing and concludes by
sending back a return value to the caller. Some functions are Boolean in
nature, returning a "yes" or "no" answer, or, more appropriately, a non-zero
or zero value, respectively. Procedures, often compared to functions, are
simply special cases, functions which do not return a value. Python
procedures are implied functions because the interpreter implicitly returns a
default value of None
40. Define Function Operator
Functions are called using the same pair of parentheses that you are used to.
In fact, some consider ( ( ) ) to be a two-character operator, the function
operator. Any input parameters or arguments must be placed between these
calling parentheses. Parentheses are also used as part of function
declarations to define those arguments.
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41. How function Declaration and Definition are different from other
programming languages
Some programming languages differentiate between function declarations
and function definitions. A function declaration consists of providing the
parser with the function name, and the names (and traditionally the types) of
its arguments, without necessarily giving any lines of code for the function,
which is usually referred to as the function definition.
In languages where there is a distinction, it is usually because the function
definition may belong in a physically different location in the code from the
function declaration. Python does not make a distinction between the two, as
a function clause is made up of a declarative header line which is
immediately followed by its defining suite
42. Define Recursion
A function is recursive if it contains a call to itself. A procedure is recursive
if a new activation can begin before an earlier activation of the same
procedure has ended. In other words, a new invocation of the same function
occurs within that function before it finished. Recursion is used extensively
in language recognition as well as in mathematical applications that use
recursive functions.
43. Define Module
A Module allows you to logically organize your pythin code. When code
gets to be large the tendency is to break it up into organized pieces that can
still interact with one another at a functioning level
44. Define importing
The process of associating attributes from other modules with your module
is called importing
45. Define namespace
A namespace is a mapping of names to objects. The process of adding a
name to namespace consists of binding the identifier to the object.
46. Define Rebinding and Unbinding
The process of changing the mapping of a name is called rebinding and the
process of removing a name is called unbinding
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47. What is name look up
When accessing an attribute, the interpreter must find it in any one of the
three namespaces (local, global and built in). This is called name look up.
48. What are the features of module import
Modules ―executed not loaded
Importing versus loading
Names imported into current namespace
Names imported into importer’s scope
49. What are the built in functions present in python for modules
_import_( )
Globals and locals
Reload_( )
50. Give the syntax for creating a class
class
ClassName:
'class documentation string"
class_suite
51. Give the syntax for creating the instance for the class
>>> class MyClass: # define class
... pass
>>> myInstance = MyClass() # instantiate class
52. How to Create a Subclasses
Derived classes are declared much like their parent class; however, a list of
base classes o inherit from are given after the
class name:
class SubClassName (ParentClass1[, ParentClass2, ...]):
'optional class documentation string'
class_suite
53. Define callable object
Any object that can be invoked with the function () operator. The function
operator is placed immediately following the name of the callable to invoke
it
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54. Define code object
There are other executable objects in python that do not have the ability to
be invoked like callable. These objects are the smaller pieces of the puzzles
that make up executable blocks of code called code object.
55. Define restricted execution and terminating execution
Restricted execution can be facilitated by rexec which can modify the
objects and bastion module which acts as a attribute filter.
A clean execution occurs only when a program runs to completion. The
execution is terminated either by exception handling or cleaner.
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