1.What is an web application ?
Ans:
A web application is a server side application runs on a server and provides
services to unlimited clients across the internet.
(OR)
Aweb application is server side application which
process a client request and provides response in the form of a web page on the
browser.
2.What
are the types of web resources?
1.static /passive web resource
2.dynamic /active web resource
3.what
is static and dynamic web resources give examples?
Which resources are executed in browser that resources are called static web
resources EX:HTML,javaScript………
Which resources are executed under server that
resources are called dynamic web resources Ex.servlets and jsp
4.What
is directory strcture of web application
5.Why
servlet technology is intruduced?
|
Before servlet technology there was a technology
called CGI(commn gateway interface)to develope server side web application.it
has two following disadvantages
1,CGI technology is failed to provide security for
the business of the application
2.CGI technology increased burdon of a server
SERVLET
technology
To overcome the above two problems servlet
technology is developed
7.what
is a SERVLET?
Servlet is a
java class ,it runs at server and provide services to multiple number of
clients across the internet
(OR) A servlet is a java class ,which knows how to
process the request and how produce a response for a request
8.how
many ways java applets are divided?
1.client side applets
2.server side applets
·
Client side applets are used for developing
GUI application
·
Server side applets are used for
developing application logic
9.What
is the difference between APPLET and SERVLET?
APPLET
SERVLET
1.An applet runs on browser OR 1.servlet runs on server
An apletviewer
2.an applet
increases browser 2.servlet increases server functionality
Functionalities
3.an applet visiable on a brows 3.a servelet invisiable in server because
Because an applet as heigh and weidh servlet doesn’t contain heigh and
width
10.What
is servlet API? 1.javax.Servlet
2.javax,Servlet.http
11.differentv
ways of creating a servlet?
1.create a java class
by implementing servlet interface
EX;
public class MyServlet implements Servlet
2.create a java class
by extending GenericServlet
EX;
public class MyServlet
extends GenericServlet
3.create a java class
by extending HttpServlet
12.Why GenericServlet is an abstract class?
GenericServelet is an
abstract class because it has one abstract method and it is implemented from
Servlet interface .so a class contains at least one abtract method that is we
hava define abstract
Note
;an
abstract class may or may not contain abstract methods.it means an abstract
class contain concret methods or all abstract methods or mix of both
13,life
cycle methods of servlet?and non life cycle methods of servlet
Life
cycle methods
1.public void
init(ServletConfig config) throws ServletException
2.public void
service(ServletRequest req,ServletResponse res) ) throws
ServletException,IOException
3.public void destroy()
Non
life cycle methods
1.init()
2.doXXX()
methods like doGet() and doPost()………..
14.where
the life cycle methods are implemented?
·
The three life cycle methods are
provided by javax.servlet.Servlet interface
·
The life cycle methods are
implemented in Servlet interface
Note
;every servlet class is either directly or indirectly implements servlet
interface
15.how many times the init(),service(),destroy() methods called to
multiple requests?
·
Init(),destroy() methods are called only
once for multiple requests
·
Service() method called by each request
means multiple times
16. servlet is a singleton class or
not?
Servlet
is not a singleton class because it will
create more then one object .in case of singleton class only one object is
created
Note
In
a server ,for a servlet class their can be more than one object also
created.another object of a servlet is created,whenever a simultaneous thread
limlt is crossed
EX;in
tomcat server maximum of 150 threads limit.ofter this limit one more object is
created
17.when servlet object is created?
Whenever
a servlet gets first request from browser
Note
Actually
a servlet class can be created in oe way that is either by directly or
indirectly implementing servlet interface
18 what is servlet configuration?
Servlet
configuration is nothing but to manage the xml fle in web container.we use
folloing tags
1.<servlet>
2.<servlet-mapping>
Every
servlet class must be registerd with the following three names in web.xml file
1.fully
qualified class name of servlet
2
alias name of a servlet
3.url
pattern of servlet
19
what is deployeement descriptor?
Web.xml
file is called deployeement descriptor
20.what is default port number of
tomcat and hoe to change it?
Tomcat
default port number is 8080 .to change this port no go to following path
C;/program
files/apche s/w foundation/toncat7/conf/server.xml
21 what are the steps to execute a
servlet application?
1.create
a web application directory strcture
2.develope
a servlet java program
3.configure
a servlet using web.xml file
4.compaile
the servlet java program
5
deployee the web application in to web
apps folder in server
6
start the server
7open
the browser type the request
22
why second request response is faster
than first request response to a servler?
When
first request is made then a web
container do’s the following
1creates
the object
2.intilize
the object
3.provide
a service to object
This
above steps takes some time
When
the second request is made then already container object is available in the
server so directly provides service to request
it will take less time so second request gets faster response then first
request
23 why every servlet class must be
public?
In
a server a container is creates an objects of a servlet class by calling newi]
Instance()
New
Instance() can create an object for a class,if that class is public class so
every servlet class must be a public
class
24 what are the kind of
deployeements in web application?
We
have three kinds of deployeements in web application
1
hard deployeement
2.console
deployeement
3
tool-based deployeement
25 HTML to servlet communication?
1
communicating through an hyperlink(staic input values)
2
communicating through submit button(dynamic
input values)
3communiating
through java script code(asynchronous communication)
26 can you configure more then one
url pattern for a servlet in web.xml (or) not?
Yes,we
have following two approaches
1.<servlet-mapping>
<servlet-name>sone</servlet-name>
<url-pattern>/srv1</url-pattern>
<url-pattern>/srv2</url-pattern>
.</servlet-mapping>
2 nd way
.<servlet-mapping>
<servlet-name>sone</servlet-name>
<url-pattern>/srv1</url-pattern>
.</servlet-mapping>
.<servlet-mapping>
<servlet-name>sone</servlet-name>
<url-pattern>/srv2</url-pattern>
.</servlet-mapping>
27 can
you add any new sub tag in a <servlet-mapping> tag (or) not?
No,the
only tags allowed into <servlet
-mapping >is
<servlet-name>and<url-pattern> tags
28 why <load –on-stratup>
tag?
This
tag is inform to container to create my servlet object immediately without
waiting for request
29 where will you placed
<load-on-startup> in web.xml?
Under
the <servlet>tag we placed this tag in web.xml
30 when we will give
,<load-on-startup> tag value is negative then container throws an
exception or not?
Will
not thrown exception,but it will ignores(waiting) to create object
Waits
for first request
What method is used to specify a containers Layout? setLayout()
31
how to read environment variables from a servlet?
Servletconfig.getparameter(string
pram-name)
32
what is the difference between http Get method and post method?
Get
method Post
method
1 .By using Get method
we can 1.By using post method we
can
Send limited amount of data from send any size of data at a time
Browser to server. This method from browser to server.it is
Canot send more then one 1KB suitable for sending more amounts
Of data at a time of data to
server
2.this method appends the data 2.this method doesn’t append the
Entered in a form to the url of form data the url in address bar
Address bar .it will show the secrect so
this method is secured then
Data like password also so this Get method
Method is not a secured method
3. this method is
doesn’t support 3.this method supports file
File uploading uploading
4.Get method request is 4.post method
request is called
Called idempotent request an non-idempotent
request
33
what is idempotent request and non idempotent
request?
1.An idempotent request
means ,a request sent to server to get a
File or page from
server
2.Non-idempotent
request mens,a request given to server for doing
Some
processing(calculations)at server side
33
what are the archive files in jdk?
We have three archive
files in jdk
1.jar(java archive)
2.war(web archive)
3.ear(enterprise
archive)=jar+ war
34.what
is default servlet?
If a servlet is
configured in web.xml with url pattern
as /(forward slash)then that servlet is called default servlet
In web.xml only one
servlet is act as a default servlet
35.when container calls default servlet?
For a given request if
no servlet is matched then the containe calls
Default servlet
36.where
servlet is configured and who wiil take care about servlet?
Servlet is configured
in web.xml file.
The web container take
care about of servlet
37
can you use same url patterns in web.xml file or not?
No,because url patterns
are uniqe In web.xml file
38 what
are the types of url-patterns ?
Ø Exact match(means
typed url-pattern and in web.xml url-pattern must be same)
Ø Directory match(starts
with \ and ends with*)
Ø Extension match(starts
with * .any name)
Ø
39 What many methods to read
request parameters?
1.getParameter()
It is used to read only
one request parameter at a time
Syntax:
public String getParameter(paramname)
2.getParameterValues()
It is used to read
single and multiple values at a time
Syntax:public
String[] getParameterValues(paramname)
3.getParameterNames()
It is used to read all
parameters names of a servlet request
Syntax:public
Enumaration getParameterNames()
4. GetParameterMap ()
It is used to store all
request parameters keys, and their values into a
Collection of type Map
Syntax:
public Map getParameterMap ()
40
can we write a parameterized constructer in a served class or not?
Sometimes yes and some
time no.
1.every servlet class
must be a public zero argument constructer
2.if we explicitly add
a zero argument constructer then we can also add a paramterized constructer to
a servlet class but without writing zero argument constructer we cant write
parameterized constructer in a servlet class
41
can we write main() method in a servlet class or not?
Yes,but main() method
is not called by the container.becoz it is not a life cycle method of
servlet.the container only calls life cycles methods of servlet
42.can
we write any user defined methods in a servlet class or not?
Yes,but user defined
methods will not called by the container.becoz those are not a life cycle
methods of servlet
42
what is life cycle init method and non life cycle init method?
Life cycle init method
contains a parameter init(ServletConfig comfit).it is given by Servlet
interface.non life cycle init method contains no parameter like init().it is
given by GenericServlet.
43.
why HttpServlet made as abstract
class without abstract methods?
If Httpservlet is not
made as abstract then a servlet programmer can create any number of objects it
increases the burdon of server so,in order to restrict programmers from
creating objects ,servlet technology developers made as HttpServlet as an
abstract class.
44.If
a servlet doesn’t contain doGet() method for a get request or doPost() method
for a post request then what happens?
If there is no suitable
method in our class then container indirectly calls base class doGet(0 or
doPost() methods.the base class doGet() or doPost()methods raises Http status
405 error message on browser.
45
In HttpServlet how many init() and service() methods are there?
Two init () and two service
() methods are there in HttpServlet class
46.Is
HttpServletRequest, HttpServletResponse are classes OR interfaces?
These are interfaces of
javax.servlet.* package
47.Is
there any relationship between ServletRequest and HttpServletRequest?
Yes,HttpServletRequest
is derived from ServletRequest.similarlly HttpServletResponse is derived from
ServletResponse
48.In
service(request,response) life cycle method req and res are objects OR
references?
R
eferences.
Internally a container
creates objects of implementation classess of ServletRequest and ServletResponse
interfaces ofter that a container passes those objects to service
method.service method receives into req and res references
49.In
java can we find an implementation class
name by using an interface reference OR not?
EX:String
str=request.getClass().getName();
50.what
is diference between web server and
application server?
Web
server Application
server
>It is a
small server >It is a big
server
>It provides only
web container.so >It provides
both web and ejb
It supports only
servlets and jsp containers so
it supports
Tehnologies
servlets,jsp and ejbs
>It has no
managed servers >it
has managed servers
>It as less
resources and services >it as
more resources and services
>It allows
war files has deployable >It
allows war ,er and jar files as deployable
51.what
is the deference between constructer and life cycle init() method of a servlet?
ServletConfig object is
not accessable in constructer but aceessable to init() method.in a servlet to
inilized an objet init method is better then contructer
52.when
overriding a base class method in
derived class we can add a checked exception for throws statement or
not?
No.We canot add checked
exception,but we can a unchecked exception
53
what is the difference b/w init parameters and context parameters?
b)init parameters are
configured inside the servlet tag but context parameters are configured outside
of a servlet tag
a)init parameters are
local to a servlet but context parameters are global to a servlet
54.what
are the different types of parameters are configured in web.xml?
1.init parameters
2.context parameters
55.what are the different types of parameters in
servlet?
1.request parameters
2.init parameters
3.context parameters
56.
what are the differences b/w ServletConfig and ServletContext objects?
ServletConfig
ServletContext
1.config object is
local object 1.context
object is global
to a servlet
object to a servlet
2.the ratio b/w config
object 2.the ratio b/w
context
and servlet object is
1:1 object
and servlet object
3.config object doesnot
exists is 1:n
Without a servlet object 3.context object exist
without
4.config objects
doesn’t a
servlet object
Store attributes 4.context
object stores both
Parameters and attributes
57.
How can we create ServletContext object?
1 ServletContext
ctx=getServletContext();
2 ServletContext ctx=config.getServletContext
();(if we write life cycle init method use this otherwise go for one)
58
How can we get ServletConfig object ?
1.super.init(cg);
2.ServletConfig
cg=getServletConfig();
59.what
are the different MIME types in servlet?
1.text/html --------àhtml
document(default mime type)
2.text/xml-----------àxml
document
3 text.xhtml----------àxhtml
4.image/gif-----------àgif
image file
5.application/jar----àjar
file
6 application/pdf-----àpdf
file
7 application/und.ms-excel----àms
excel
8.application/octet.stream-----à(common
mime type for all types responses)
60
. What are the different types of communication in servlets?
We have 4 types of communication in servlet
1.
Browser to servlet communi……
2. Html to servlet communi…………
3. Applet to servlet communi……..
4. Servlet to sevlet communi………
61.
What is servlet collaboration? OR how many ways two servlets can communicate?
Communication between
two servlets is servlet collaboration.two servlets can communicate in three
ways
1. RequestDispatcher forward () and
include() methods
2. using sendRedirect() method of Response
object
62.How many ways to get Request
Dispatcher object ?
We have three ways to
get RequestDispatcher,
1.by
using Request interface
RequestDispatcher rd
=request.getRequestDispatcher(“request relative path”);
2.by using Context interface
RequestDispatcher rd=context.get
RequestDispatcher(“/context releative path”);
3.by using Context
interface method of getNamedDispatcher
RequestDispatcher
rd=context.getNamedDispatcher(“alias name of servlet”);
63.
What is the diff b/w request based getRequestDispatcher () and context based getRequestDispatcher()?
In request based method
we pass request relative path as parameter but in context based we pass context
relative path as a parameter
64.
what is the diff b/w forwarding and redirecting?
Forwarding
1.In this ,client
doesn’t no About forwarding
2.in this only one pair
of (req,res) objects are created shared by source and destination servlets
3.in this along with
the request ,paraneters also qutomatically forwards to destination
4.In this to forward
any req the source and destination servlets must be in same server
5.In this the
deatination should be a java type(servlet,jsp ,html)
redirecting
1.In this ,client knows
about redirecting
2.in this separate pair
of req and res objects are created by the container for a source and
destination servlets
3.in this req is
redirected from a source to destination
,but the parameters will not be redirected
4.to redirect a req,
source and destination servlets in same
server or different server
5.In this the
deatination should be a java type(servlet,jsp ,html) or non java type
65.can
we redirect along with the request or not?
Yes.the parameters are
not automatically redirected but we can explicitly attach the parameters ,in
the form of a queay string
Ex:reponse.sendRedirect(“srv2?p1=100&p1=200”);
66.How
to refresh the webpage generated by
servlet automatically at regular intervals?
Response.setHeader(“Refresh”,”5”);
The
above statement refreshes the browser every 5 seconds
67
can you give me some list of HttpRequestHeader and HttpResponseHeaders
httpRequestHeader
1.
cookie
2.host
3.referer
4.accept
5.
accept-language
6.accept-encoding
7.user-agent
8connection
9.keep-alive
10.if-modified-since
httpResponseHeaders
are
1.Location
2.Refresh
3.set-cookie
4content-type
5.content-length
6.content-encoding
7.last-modified
8.cache-control/param
68.how
many no of sessions objects are created at server side?
It depends on the no of
clients,always the no of clients and no of session objects are equal
69.can
one client share the data of a session
object of another client or not?
NO.
It is possible to share
the data of context object by the entire client
70.How
can we find a web-site is using url-rewriting technique for session tracking or
not?
We can find by
observing sessionId in the url of
Address bar
71.Why
all real time applications prefer url-rewriting?
A web-sit developer is
unknown about whether a client is accepting or rejecting the cookies
Eventhough a browser
reject cookies but still session tracking to be executed in a realtime project
for this url-rewriting is used
72.What
are the scopes in servlets?
1.request
2.session
3.context(also
called as application scope)
Request is least scope
and context is highest scopes
73.
How can u create multiple tomcat insatances?
Copy and past the
existing installed tomcat rename to some name
then go to server config file increment port number by one where u have port
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