http session event
Hi,
I am going thorugh below example
http://www.javatpoint.com/HttpSessionEvent
I wonder when below method getting called
public void sessionDestroyed(HttpSessi
21. current--;
22. ctx.setAttribute("currentu
23. }
please advise
Any links resources ideas highly appreciated. Thanks in advance
I am going thorugh below example
http://www.javatpoint.com/HttpSessionEvent
I wonder when below method getting called
public void sessionDestroyed(HttpSessi
21. current--;
22. ctx.setAttribute("currentu
23. }
please advise
Any links resources ideas highly appreciated. Thanks in advance
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>I am not clear how session can be maintained across multiple connections .
The Servlet container uses an id to identify the user's session. When a request is received by the container, it checks for a session id. If the container finds a session id in the request, then it checks to see if there is a valid session associated with that id. Let's suppose that you browsed to a site and have created a session. You can use that same browser to open a second window(tab in browser) and make a new request to the same site. If you are using cookies, then the browser will send the session cookie that was made for the first window. Both windows will be in the same session but will have made separate connections.
You can use the following demonstration JSP.
You can use that code to see how the session tracking mechanisms work. If you have questions about it,then ask us here.
As for your question at the top, the sessionDestroyed method is called when the session is timed out or when you use
The Servlet container uses an id to identify the user's session. When a request is received by the container, it checks for a session id. If the container finds a session id in the request, then it checks to see if there is a valid session associated with that id. Let's suppose that you browsed to a site and have created a session. You can use that same browser to open a second window(tab in browser) and make a new request to the same site. If you are using cookies, then the browser will send the session cookie that was made for the first window. Both windows will be in the same session but will have made separate connections.
You can use the following demonstration JSP.
<%
String path = request.getServletPath() + request.getContextPath();
String encodedPath = response.encodeURL(path);
Integer count = (Integer)session.getAttribute("count");
if(count==null)count = new Integer(0);
session.setAttribute("count",new Integer(count.intValue() + 1));
%>
The session id is ${pageContext.session.id}<br/>
Is the session new? ${pageContext.session['new']}<br/>
Did the client send the session id in the url? ${pageContext.request.requestedSessionIdFromURL}<br/>
Did the client send the session id in a cookie? ${pageContext.request.requestedSessionIdFromCookie}<br/>
path is <%=path%><br/>
encodedPath is <%=encodedPath%> <br/>
count=<%=count%><br/><br/>
<a href="<%=path%>">Not encoded request</a><br/><br/>
<a href="<%=encodedPath%>">Encoded request</a><br/>You can use that code to see how the session tracking mechanisms work. If you have questions about it,then ask us here.
As for your question at the top, the sessionDestroyed method is called when the session is timed out or when you use
session.invalidate();ASKER
You can use that same browser to open a second window(tab in browser) and make a new request to the same site. If you are using cookies, then the browser will send the session cookie that was made for the first window. Both windows will be in the same session but will have made separate connections.
I opened my bank account in one tab of chrome browser and it asked me to login. I gave usernmae and password and logged in. I opened other tab in same chrome browser. It is again asking me to enter user name and password. If i enter then it will link to old session object that i logged earlier. please advise
>I opened other tab in same chrome browser. It is again asking me to enter user name and password.
What page did you browse to ? What did you type(or paste) into the address bar?
Did you go to login page? The log-in page doesn't look for the cookie. Or did you copy the address from the first tab after you were logged in? That second thing is what I would try. The browser should send the cookie that you already obtained in first tab.
What page did you browse to ? What did you type(or paste) into the address bar?
Did you go to login page? The log-in page doesn't look for the cookie. Or did you copy the address from the first tab after you were logged in? That second thing is what I would try. The browser should send the cookie that you already obtained in first tab.
ASKER
i typed
https://www.bankofamerica.com/
It said welcome back, xyz
then xy*** with sign In button. I clicked sign in buttom.
It went to next page where there is Your SiteKey with password. I entered my password. i successfully logged in and lead to next page with account details etc.
I copied the url at this instace like
https://secure.bankofamerica.com/myaccounts/signin/signIn.go?isSecureMobile=false&returnSiteIndicator=GC&langPref=en-us&request_locale=en-us&capturemode=N&newuser=false&callOM=Y&bP=F
Opened new chrome browser tab and pasted above url
It said welcome back, xyz
then xy*** with sign In button. I clicked sign in buttom.
It went to next page where there is Your SiteKey with password. I re-entered my password. successfully logged in and lead to next page with account details etc.
I tried pasting url===>https://www.bankofamerica.com/ again in other tab that also
It said welcome back, xyz
then xy*** with sign In button. I clicked sign in buttom.
It went to next page where there is Your SiteKey with password. I re-entered my password. successfully logged in and lead to next page with account details etc.
Please advise why i need to enter password details in new tab even though i logged in previous tab to the bank.
https://www.bankofamerica.com/
It said welcome back, xyz
then xy*** with sign In button. I clicked sign in buttom.
It went to next page where there is Your SiteKey with password. I entered my password. i successfully logged in and lead to next page with account details etc.
I copied the url at this instace like
https://secure.bankofamerica.com/myaccounts/signin/signIn.go?isSecureMobile=false&returnSiteIndicator=GC&langPref=en-us&request_locale=en-us&capturemode=N&newuser=false&callOM=Y&bP=F
Opened new chrome browser tab and pasted above url
It said welcome back, xyz
then xy*** with sign In button. I clicked sign in buttom.
It went to next page where there is Your SiteKey with password. I re-entered my password. successfully logged in and lead to next page with account details etc.
I tried pasting url===>https://www.bankofamerica.com/ again in other tab that also
It said welcome back, xyz
then xy*** with sign In button. I clicked sign in buttom.
It went to next page where there is Your SiteKey with password. I re-entered my password. successfully logged in and lead to next page with account details etc.
Please advise why i need to enter password details in new tab even though i logged in previous tab to the bank.
>Please advise why i need to enter password details in new tab even though i logged in previous tab to the bank
I don't know. Maybe an expert can explain it.
I don't know. Maybe an expert can explain it.
@gudii9,
This sounds like it is just the way that "bankofamerica" have setup their website. Try something for me, once you login and get the list of your accounts, try "refreshing the page" and tell us.... does it still show your accounts or does it ask for your password again?
Or alternatively, to see what a typical site does, if you have a gmail account open a tab and go to gmail.com and then login. Now go to another tab and go to gmail.com again and this time it shouldn't ask you for login details.
Oh, and going back to what I wrote up the top (and your question about it), by "connection" I did not mean your internet connection, I meant each individual TCP connection. In simplistic terms, when you navigate to a webpage a TCP connection is opened to request it and get the page data back, and then the TCP connection is closed. Now if you click a link on that page to go to a new page, a new TCP connection is opened to request that new page and to retrieve it, and then that TCP connection is closed. This is what I meant about "multiple connections".
This sounds like it is just the way that "bankofamerica" have setup their website. Try something for me, once you login and get the list of your accounts, try "refreshing the page" and tell us.... does it still show your accounts or does it ask for your password again?
Or alternatively, to see what a typical site does, if you have a gmail account open a tab and go to gmail.com and then login. Now go to another tab and go to gmail.com again and this time it shouldn't ask you for login details.
Oh, and going back to what I wrote up the top (and your question about it), by "connection" I did not mean your internet connection, I meant each individual TCP connection. In simplistic terms, when you navigate to a webpage a TCP connection is opened to request it and get the page data back, and then the TCP connection is closed. Now if you click a link on that page to go to a new page, a new TCP connection is opened to request that new page and to retrieve it, and then that TCP connection is closed. This is what I meant about "multiple connections".
I did some testing.
yahoo mail, gmail, and experts-exchange.com all work the way we have described.
I guess your banking site has some extra safe guards.
The easiest way to learn about the session tracking mechanisms is to set up a stand alone Tomcat on your desktop and use the JSP that I posted above here. By the way, google's Chrome browser allows you to block cookies(ask us if you don't know how). When cookies are blocked, the session id is added the url. Go ahead and play with the JSP that I posted. You should be able to increment the count variable with and with out using cookies.
The site we are using now(experts-exchange) is built with java. If you look at the cookies for this site, then you will see one named jsessionid. But, unfortunately this site doesn't allow us to not use cookies. So, you can't see the url rewriting mechanism here.
yahoo mail, gmail, and experts-exchange.com all work the way we have described.
I guess your banking site has some extra safe guards.
The easiest way to learn about the session tracking mechanisms is to set up a stand alone Tomcat on your desktop and use the JSP that I posted above here. By the way, google's Chrome browser allows you to block cookies(ask us if you don't know how). When cookies are blocked, the session id is added the url. Go ahead and play with the JSP that I posted. You should be able to increment the count variable with and with out using cookies.
The site we are using now(experts-exchange) is built with java. If you look at the cookies for this site, then you will see one named jsessionid. But, unfortunately this site doesn't allow us to not use cookies. So, you can't see the url rewriting mechanism here.
ASKER
gmail, and experts-exchange.com all work the way we have described.
I tested too they works as you mentioned unlike bank.
google's Chrome browser allows you to block cookies(ask us if you don't know how).
Please let me know how to do it
To block cookies in Chrome:
Click on the button on the far right of the address bar.
Choose Settings in the dropdown menu.
On the bottom of the Settings page, click on "Show advanced settings...".
Under Privacy heading click "Content Settings..." button.
Under Cookies heading select "Block sites from setting any data"
Click Done.
Close browser.
Click on the button on the far right of the address bar.
Choose Settings in the dropdown menu.
On the bottom of the Settings page, click on "Show advanced settings...".
Under Privacy heading click "Content Settings..." button.
Under Cookies heading select "Block sites from setting any data"
Click Done.
Close browser.
ASKER
I ran the JSP on tomcat.
When i refresh browser URL the count is increasing as below.
The session id is 878A76B14B41BC15B2E624B857
Is the session new? true
Did the client send the session id in the url? false
Did the client send the session id in a cookie? false
path is /NewFile.jsp/CookiesProjec
encodedPath is /NewFile.jsp/CookiesProjec
count=0
Not encoded request
Encoded request
But the below links are not working
Not encoded request
Encoded request
Please advice on how to fix them.
When i refresh browser URL the count is increasing as below.
The session id is 878A76B14B41BC15B2E624B857
Is the session new? true
Did the client send the session id in the url? false
Did the client send the session id in a cookie? false
path is /NewFile.jsp/CookiesProjec
encodedPath is /NewFile.jsp/CookiesProjec
count=0
Not encoded request
Encoded request
But the below links are not working
Not encoded request
Encoded request
Please advice on how to fix them.
ASKER
You can use that code to see how the session tracking mechanisms work. If you have questions about it,then ask us here.
I ran JSP but not clear on how the session tracking mechanisms demonstrated in this jsp. Please advise
I am sorry. I made a cut paste error. I didn't notice it because I tested in my ROOT web app( which has a context path of ""). It is just the second line that has the error.
<%
String path = request.getContextPath() + request.getServletPath();
String encodedPath = response.encodeURL(path);
Integer count = (Integer)session.getAttribute("count");
if(count==null)count = new Integer(0);
session.setAttribute("count",new Integer(count.intValue() + 1));
%>
The session id is ${pageContext.session.id}<br/>
Is the session new? ${pageContext.session['new']}<br/>
Did the client send the session id in the url? ${pageContext.request.requestedSessionIdFromURL}<br/>
Did the client send the session id in a cookie? ${pageContext.request.requestedSessionIdFromCookie}<br/>
path is <%=path%><br/>
encodedPath is <%=encodedPath%> <br/>
count=<%=count%><br/><br/>
<a href="<%=path%>">Not encoded request</a><br/><br/>
<a href="<%=encodedPath%>">Encoded request</a><br/>ASKER
with new jsp i am seeing this error
HTTP Status 500 - Unable to compile class for JSP
--------------------------
type Exception report
message Unable to compile class for JSP
description The server encountered an internal error that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperEx
org.apache.jasper.JspCompi
Please advise on how to fix it
HTTP Status 500 - Unable to compile class for JSP
--------------------------
type Exception report
message Unable to compile class for JSP
description The server encountered an internal error that prevented it from fulfilling this request.
exception
org.apache.jasper.JasperEx
org.apache.jasper.JspCompi
Please advise on how to fix it
ASKER
Here is complete stack trace
May 04, 2014 3:49:23 PM org.apache.catalina.core.A
INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: C:\Program Files\Java\jre7\bin;C:\Win
May 04, 2014 3:49:23 PM org.apache.tomcat.util.dig
WARNING: [SetPropertiesRule]{Server
May 04, 2014 3:49:24 PM org.apache.coyote.Abstract
INFO: Initializing ProtocolHandler ["http-bio-8080"]
May 04, 2014 3:49:24 PM org.apache.coyote.Abstract
INFO: Initializing ProtocolHandler ["ajp-bio-8009"]
May 04, 2014 3:49:24 PM org.apache.catalina.startu
INFO: Initialization processed in 1372 ms
May 04, 2014 3:49:24 PM org.apache.catalina.core.S
INFO: Starting service Catalina
May 04, 2014 3:49:24 PM org.apache.catalina.core.S
INFO: Starting Servlet Engine: Apache Tomcat/7.0.52
May 04, 2014 3:49:25 PM org.apache.coyote.Abstract
INFO: Starting ProtocolHandler ["http-bio-8080"]
May 04, 2014 3:49:25 PM org.apache.coyote.Abstract
INFO: Starting ProtocolHandler ["ajp-bio-8009"]
May 04, 2014 3:49:25 PM org.apache.catalina.startu
INFO: Server startup in 1286 ms
May 04, 2014 3:49:28 PM org.apache.catalina.core.S
SEVERE: Servlet.service() for servlet [jsp] in context with path [/CookiesProject] threw exception [Unable to compile class for JSP] with root cause
java.io.IOException: tmpFile.renameTo(classFile
at org.apache.jasper.compiler
at org.apache.jasper.compiler
at org.apache.jasper.compiler
at org.apache.jasper.compiler
at org.apache.jasper.compiler
at org.apache.jasper.compiler
at org.apache.jasper.JspCompi
at org.apache.jasper.servlet.
at org.apache.jasper.servlet.
at org.apache.jasper.servlet.
at javax.servlet.http.HttpSer
at org.apache.catalina.core.A
at org.apache.catalina.core.A
at org.apache.tomcat.websocke
at org.apache.catalina.core.A
at org.apache.catalina.core.A
at org.apache.catalina.core.S
at org.apache.catalina.core.S
at org.apache.catalina.authen
at org.apache.catalina.core.S
at org.apache.catalina.valves
at org.apache.catalina.valves
at org.apache.catalina.core.S
at org.apache.catalina.connec
at org.apache.coyote.http11.A
at org.apache.coyote.Abstract
at org.apache.tomcat.util.net
at java.util.concurrent.Threa
at java.util.concurrent.Threa
at java.lang.Thread.run(Unkno
Please advice.
May 04, 2014 3:49:23 PM org.apache.catalina.core.A
INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: C:\Program Files\Java\jre7\bin;C:\Win
May 04, 2014 3:49:23 PM org.apache.tomcat.util.dig
WARNING: [SetPropertiesRule]{Server
May 04, 2014 3:49:24 PM org.apache.coyote.Abstract
INFO: Initializing ProtocolHandler ["http-bio-8080"]
May 04, 2014 3:49:24 PM org.apache.coyote.Abstract
INFO: Initializing ProtocolHandler ["ajp-bio-8009"]
May 04, 2014 3:49:24 PM org.apache.catalina.startu
INFO: Initialization processed in 1372 ms
May 04, 2014 3:49:24 PM org.apache.catalina.core.S
INFO: Starting service Catalina
May 04, 2014 3:49:24 PM org.apache.catalina.core.S
INFO: Starting Servlet Engine: Apache Tomcat/7.0.52
May 04, 2014 3:49:25 PM org.apache.coyote.Abstract
INFO: Starting ProtocolHandler ["http-bio-8080"]
May 04, 2014 3:49:25 PM org.apache.coyote.Abstract
INFO: Starting ProtocolHandler ["ajp-bio-8009"]
May 04, 2014 3:49:25 PM org.apache.catalina.startu
INFO: Server startup in 1286 ms
May 04, 2014 3:49:28 PM org.apache.catalina.core.S
SEVERE: Servlet.service() for servlet [jsp] in context with path [/CookiesProject] threw exception [Unable to compile class for JSP] with root cause
java.io.IOException: tmpFile.renameTo(classFile
at org.apache.jasper.compiler
at org.apache.jasper.compiler
at org.apache.jasper.compiler
at org.apache.jasper.compiler
at org.apache.jasper.compiler
at org.apache.jasper.compiler
at org.apache.jasper.JspCompi
at org.apache.jasper.servlet.
at org.apache.jasper.servlet.
at org.apache.jasper.servlet.
at javax.servlet.http.HttpSer
at org.apache.catalina.core.A
at org.apache.catalina.core.A
at org.apache.tomcat.websocke
at org.apache.catalina.core.A
at org.apache.catalina.core.A
at org.apache.catalina.core.S
at org.apache.catalina.core.S
at org.apache.catalina.authen
at org.apache.catalina.core.S
at org.apache.catalina.valves
at org.apache.catalina.valves
at org.apache.catalina.core.S
at org.apache.catalina.connec
at org.apache.coyote.http11.A
at org.apache.coyote.Abstract
at org.apache.tomcat.util.net
at java.util.concurrent.Threa
at java.util.concurrent.Threa
at java.lang.Thread.run(Unkno
Please advice.
You were able to compile my original JSP.
Now, you must have a problem with your configuration. Are you able to run a simple hello JSP?
What is your configuration?
Are you running Tomcat within Eclipse? Since I see Kepler on your library path, I guess you are doing that. Please correct me if I wrong in my assumption.
I am not an eclipse expert. But, I will try to help you. I googled for some ideas.
Did you try cleaning your project?(click on clean in dropdown menu from clicking on Project at top menu bar)
I guess that you didn't change any permissions on your folders and you have permission to write to wherever tmpfile is being written. Is that correct?
Click on Server tab on Java EE perspective, double click on your Tomcat server. A Overview page should open up. Can you show us that?
Now, you must have a problem with your configuration. Are you able to run a simple hello JSP?
What is your configuration?
Are you running Tomcat within Eclipse? Since I see Kepler on your library path, I guess you are doing that. Please correct me if I wrong in my assumption.
I am not an eclipse expert. But, I will try to help you. I googled for some ideas.
Did you try cleaning your project?(click on clean in dropdown menu from clicking on Project at top menu bar)
I guess that you didn't change any permissions on your folders and you have permission to write to wherever tmpfile is being written. Is that correct?
Click on Server tab on Java EE perspective, double click on your Tomcat server. A Overview page should open up. Can you show us that?
ASKER
Are you running Tomcat within Eclipse? Since I see Kepler on your library path, I guess you are doing that. Please correct me if I wrong in my assumption.
that is correct. I am using eclipse kepler with tomcat
You were able to compile my original JSP.
That i had initially compilation errors similar to now. But those resolved by themselves after eclipse, laptop restarts somehow. But now they are not going off. Not sure what is eclipse issue behind this.
ASKER
Now it worked.
what is difference beween below links
Not encoded request
Encoded request
Both are incrementin g count similar to browser url refresh which also increments count.
please advice
what is difference beween below links
Not encoded request
Encoded request
Both are incrementin g count similar to browser url refresh which also increments count.
please advice
>Now it worked.
Good.
>what is difference beween below links
The encoded request has the session id written in the url if cookies are blocked. If the session cookie is used, then they are the same.
Good.
>what is difference beween below links
The encoded request has the session id written in the url if cookies are blocked. If the session cookie is used, then they are the same.
When the session is new, the encoded url always has the session id in it. That is because the servlet container(Tomcat) doesn't know how or if the client will join the session. At this point in time, the client hasn't sent the cookie back yet or alternatively hasn't sent an encoded request.
ASKER
I see Not encoded request also incrementing the count. I wonder if that also has session id in it. please advice. I am still not able to get complete picture about this whole thing
There are two different mechanisms that the servlet container(Tomcat) can use to track the user through his session. The servlet container can use a session cookie to hold the session id or encode the session id in urls. The cookie mechanism is automatically handled by the servlet container and the user's browser. But, if the cookie is not accepted by the browser, then the servlet container can encode urls that it sends in it's response. This doesn't happen automatically. The web app coder must run his urls through the response.encodeURL(url). The coder can make a habit of this because the servlet container will not bother encoding the urls if the session cookie is used.
For the first request from the user to the servlet container, he hasn't joined the session yet. So, for the first response, the servlet container will send the session cookie and encode the urls (if the coder has used the response.encodeURL method on his urls). The container will do both because the session is new and it doesn't know yet which mechanism the client will use to identify himself for the session.
If you browse to the JSP that I posted, you see this in the first response . The encoded request has the session id in it and the cookie has been sent.
To see the session cookie in your Chrome browser:
Go to the Content settings page.
Under Cookies heading, click on the "All cookies and site data..." button.
In the list, click on your site to see the cookie(assuming that you didn't block it).
Click on the cookie to see it's contents.
If the user decides to join the session, then in his second request he must send the cookie back(done automatically by the browser) or use the encoded link. When the container receives the second request that contains the session id, it can identify the user and maintain his session. At this point, the session is no longer new. In subsequent responses the container will use the mechanism the user has decided to use. This is assuming that the coder has encoded all the urls in the links to his site.
You should be able to increment the count variable in my JSP using either tracking mechanism.
All this is specified in the "Java Servlet Specification". You can download the file
servlet-3_0-final--spec.pd
from
http://download.oracle.com/otndocs/jcp/servlet-3.0-fr-eval-oth-JSpec/
You should read the whole thing if you want to learn the Servlet technology.
For the first request from the user to the servlet container, he hasn't joined the session yet. So, for the first response, the servlet container will send the session cookie and encode the urls (if the coder has used the response.encodeURL method on his urls). The container will do both because the session is new and it doesn't know yet which mechanism the client will use to identify himself for the session.
If you browse to the JSP that I posted, you see this in the first response . The encoded request has the session id in it and the cookie has been sent.
To see the session cookie in your Chrome browser:
Go to the Content settings page.
Under Cookies heading, click on the "All cookies and site data..." button.
In the list, click on your site to see the cookie(assuming that you didn't block it).
Click on the cookie to see it's contents.
If the user decides to join the session, then in his second request he must send the cookie back(done automatically by the browser) or use the encoded link. When the container receives the second request that contains the session id, it can identify the user and maintain his session. At this point, the session is no longer new. In subsequent responses the container will use the mechanism the user has decided to use. This is assuming that the coder has encoded all the urls in the links to his site.
You should be able to increment the count variable in my JSP using either tracking mechanism.
All this is specified in the "Java Servlet Specification". You can download the file
servlet-3_0-final--spec.pd
from
http://download.oracle.com/otndocs/jcp/servlet-3.0-fr-eval-oth-JSpec/
You should read the whole thing if you want to learn the Servlet technology.
ASKER
I will read it. I heard after MVC introduction in 2000 year no need to worry about the servlets, jsps as mvc frameworks like struts, spring takes care of it. Is that assumption is correct and safe?
ASKER
When i click link below link multiple times
Encoded request
I see jsp output as below
The session id is 5C776E6379BDA2C63DAB5155F3
Is the session new? false
Did the client send the session id in the url? false
Did the client send the session id in a cookie? true
path is /CookiesProject/NewFile.js
encodedPath is /CookiesProject/NewFile.js
count=12
My question is since i click 'Encoded request'(which i suppose not cookie but URL rewriting encoding mechanism) so below line must come false right instead of true
Did the client send the session id in a cookie? true
Also below line must come true instead of false right.
Did the client send the session id in the url? false
Please advise.
Encoded request
I see jsp output as below
The session id is 5C776E6379BDA2C63DAB5155F3
Is the session new? false
Did the client send the session id in the url? false
Did the client send the session id in a cookie? true
path is /CookiesProject/NewFile.js
encodedPath is /CookiesProject/NewFile.js
count=12
My question is since i click 'Encoded request'(which i suppose not cookie but URL rewriting encoding mechanism) so below line must come false right instead of true
Did the client send the session id in a cookie? true
Also below line must come true instead of false right.
Did the client send the session id in the url? false
Please advise.
ASKER
<%
String path = request.getContextPath() + request.getServletPath();
String encodedPath = response.encodeURL(path);
Integer count = (Integer)session.getAttribute("count ");
if(count==null)count = new Integer(0);
session.setAttribute("count",new Integer(count.intValue() + 1));
%>
why jsp preview is not showing above code.
Also how the count is incrementing no matter which link i click. Please advice
>I heard after MVC introduction in 2000 year no need to worry about the servlets, jsps as mvc frameworks like struts, spring takes care of it
That is a good question. Please ask a new question in this topic area. It will be interesting to read comments from the experts.
Personally, I don't use a frameworks. As far as Java on the server is concerned, I use Servlets, JSP, JSTL, JDO, and tag files.
That is a good question. Please ask a new question in this topic area. It will be interesting to read comments from the experts.
Personally, I don't use a frameworks. As far as Java on the server is concerned, I use Servlets, JSP, JSTL, JDO, and tag files.
My question is since i click 'Encoded request'(which i suppose not cookie but URL rewriting encoding mechanism) so below line must come false right instead of true
Did the client send the session id in a cookie? true
Since the client sent the session cookie, Tomcat doesn't bother encoding the urls. It doesn't matter which link you use.
Also below line must come true instead of false right.
Did the client send the session id in the url? false
No, since the sesssion cookie is being used, Tomcat will not bother encoding any url.
If you BLOCK cookies, then after you click on the "Encoded" request link 3 times, you should see the following.
The session id is 8A6190F0DED4014576F814FD5EIf next you click on the "Not encoded" request link, then you will lose the current session. You will lose it because you didn't send the session id in a cookie or in your url. You should see something like the following.23164F
Is the session new? false
Did the client send the session id in the url? true
Did the client send the session id in a cookie? false
path is /sessionTest.jsp
encodedPath is /sessionTest.jsp;jsessionid=8A6190F0 DED4014576 F814FD5E23 164F
count=3
The session id is E4B9414949F65186BFE42A0D6AThe container sent a different session id and the session is new. Now click on the "Encoded" request link. You should see the following.BEC2D4
Is the session new? true
Did the client send the session id in the url? false
Did the client send the session id in a cookie? false
path is /sessionTest.jsp
encodedPath is /sessionTest.jsp;jsessionid=E4B94149 49F65186BF E42A0D6ABE C2D4
count=0
The session id is E4B9414949F65186BFE42A0D6AThe session has been maintained because Tomcat was asked by the web app coder(me) to send the encoded url in the last response and the user sent it back to Tomcat in his current request.BEC2D4
Is the session new? false
Did the client send the session id in the url? true
Did the client send the session id in a cookie? false
path is /sessionTest.jsp
encodedPath is /sessionTest.jsp;jsessionid=E4B94149 49F65186BF E42A0D6ABE C2D4
count=1
>why jsp preview is not showing above code.
That is not a preview. That is a scriptlet. That code is executed on the server and is not part of the output. You need to know how JSP and Servlets work. Basically the requested Servlet does some code execution and outputs some HTML(most common) to the client for a response .
That is not a preview. That is a scriptlet. That code is executed on the server and is not part of the output. You need to know how JSP and Servlets work. Basically the requested Servlet does some code execution and outputs some HTML(most common) to the client for a response .
ASKER
I went to chrom settings and cookie settings to see below cookie data
Name: JSESSIONID
Content: 1C4B3E5FA36216578F5B52F2CA
Domain: localhost
Path: /CookiesProject/
Send for: Any kind of connection
Accessible to script: No (HttpOnly)
Created: Tuesday, May 6, 2014 2:10:39 PM
Expires: When the browsing session ends
Now it make sense why it is true for cookie
The session id is 1C4B3E5FA36216578F5B52F2CA
Is the session new? false
Did the client send the session id in the url? false
Did the client send the session id in a cookie? true
path is /CookiesProject/NewFile.js
encodedPath is /CookiesProject/NewFile.js
count=1
How to block cookie in chrome to test url encoding mechanism as well. Please advise
Name: JSESSIONID
Content: 1C4B3E5FA36216578F5B52F2CA
Domain: localhost
Path: /CookiesProject/
Send for: Any kind of connection
Accessible to script: No (HttpOnly)
Created: Tuesday, May 6, 2014 2:10:39 PM
Expires: When the browsing session ends
Now it make sense why it is true for cookie
The session id is 1C4B3E5FA36216578F5B52F2CA
Is the session new? false
Did the client send the session id in the url? false
Did the client send the session id in a cookie? true
path is /CookiesProject/NewFile.js
encodedPath is /CookiesProject/NewFile.js
count=1
If you BLOCK cookies, then after you click on the "Encoded" request link 3 times, you should see the following.
How to block cookie in chrome to test url encoding mechanism as well. Please advise
ASKER
If next you click on the "Not encoded" request link, then you will lose the current session. You will lose it because you didn't send the session id in a cookie or in your url. You should see something like the following.
The session id is E4B9414949F65186BFE42A0D6ABEC2D4
Is the session new? true
Did the client send the session id in the url? false
Did the client send the session id in a cookie? false
path is /sessionTest.jsp
encodedPath is /sessionTest.jsp;jsessionid=E4B94149 49F65186BF E42A0D6ABE C2D4
count=0
Not encoding is third mechanism( i see both cookie and url reqriting are coming false for you) apart from cookies mechanism, url rewriting mechanism.
If next you click on the "Not encoded" request link, then you will lose the current session. You will lose it because you didn't send the session id in a cookie or in your url. You should see something like the following
but for me instead of false false always coming false true as given below even after clicking Not encoded request link many times.
The session id is 1C4B3E5FA36216578F5B52F2CA65DAC3
Is the session new? false
Did the client send the session id in the url? false
Did the client send the session id in a cookie? true
path is /CookiesProject/NewFile.jsp
encodedPath is /CookiesProject/NewFile.jsp
count=16
Not encoded request
Encoded requestHow do i see false false like your output. please advise
>I went to chrom settings and cookie settings to see below cookie data
Ok good. You can find the cookies that your browser is storing.
>How to block cookie in chrome to test url encoding mechanism as well. Please advise
I already posted that at
https://www.experts-exchange.com/questions/28407296/http-session-event.html?anchorAnswerId=40033915#a40033915
>Not encoding is third mechanism( i see both cookie and url reqriting are coming false for you) apart from cookies mechanism, url rewriting mechanism.
I only described two mechanisms. I don't know what third mechanism that you are talking about.
>but for me instead of false false always coming false true as given below even after clicking Not encoded request link many times.
You have the session cookie stored. You can look in Chrome's "Cookies and site data" page.
When the output is
Did the client send the session id in a cookie? true
That means that your browser sent the cookie.
>How do i see false false like your output. please advise
You must block the cookie. For an experiment try clicking on the remove button(it is below the cookie data).
Ok good. You can find the cookies that your browser is storing.
>How to block cookie in chrome to test url encoding mechanism as well. Please advise
I already posted that at
https://www.experts-exchange.com/questions/28407296/http-session-event.html?anchorAnswerId=40033915#a40033915
>Not encoding is third mechanism( i see both cookie and url reqriting are coming false for you) apart from cookies mechanism, url rewriting mechanism.
I only described two mechanisms. I don't know what third mechanism that you are talking about.
>but for me instead of false false always coming false true as given below even after clicking Not encoded request link many times.
You have the session cookie stored. You can look in Chrome's "Cookies and site data" page.
When the output is
Did the client send the session id in a cookie? true
That means that your browser sent the cookie.
>How do i see false false like your output. please advise
You must block the cookie. For an experiment try clicking on the remove button(it is below the cookie data).
ASKER
I blocked the cookie and saw both false and false as below
The session id is F280FB1A8371400F1459DE04E9
Is the session new? true
Did the client send the session id in the url? false
Did the client send the session id in a cookie? false
path is /CookiesProject/NewFile.js
encodedPath is /CookiesProject/NewFile.js
count=0
Not encoded request
Encoded request
Now URL rewriting mechanism seems kicked in.
I wonder why the count is not increasing when i click
Not encoded request
I see when i blocked cookies gmail stopped working. How to unblock cookies again so that gmail works. what is the default option i have to click back
( is it is ---->Allow local data to be set (recommended)??)
I got this error
Oops! Your browser seems to have cookies disabled. Make sure cookies are enabled or try opening a new browser window. [?]
(
experts exchanges works fine even after blocking cookies)
The session id is F280FB1A8371400F1459DE04E9
Is the session new? true
Did the client send the session id in the url? false
Did the client send the session id in a cookie? false
path is /CookiesProject/NewFile.js
encodedPath is /CookiesProject/NewFile.js
count=0
Not encoded request
Encoded request
Now URL rewriting mechanism seems kicked in.
I wonder why the count is not increasing when i click
Not encoded request
I see when i blocked cookies gmail stopped working. How to unblock cookies again so that gmail works. what is the default option i have to click back
( is it is ---->Allow local data to be set (recommended)??)
I got this error
Oops! Your browser seems to have cookies disabled. Make sure cookies are enabled or try opening a new browser window. [?]
(
experts exchanges works fine even after blocking cookies)
One more helpful hint that I just noticed:
After you have gone through the settings page and performed the steps to block cookies that I posted, when the Chrome browser blocks a cookie, it displays a brown cookie with a red X across it. You should see that icon in the address bar. It should appear right next to the bookmark star. If you click on the cookie icon it will open up a dialog box.
After you have gone through the settings page and performed the steps to block cookies that I posted, when the Chrome browser blocks a cookie, it displays a brown cookie with a red X across it. You should see that icon in the address bar. It should appear right next to the bookmark star. If you click on the cookie icon it will open up a dialog box.
>Now URL rewriting mechanism seems kicked in.
Good. We are getting somewhere.
>I wonder why the count is not increasing when i click Not encoded request
If you have cookies blocked and don't use encoded url, then the server can't identify you.
>How to unblock cookies again so that gmail works. what is the default option i have to click back
( is it is ---->Allow local data to be set (recommended
Yes
Or click on that cookie icon that I described in my last comment.
>experts exchanges works fine even after blocking cookies)
Isn't the cookie for experts-exchange already stored ?
I think blocking cookies means that no new ones will be accepted.
Good. We are getting somewhere.
>I wonder why the count is not increasing when i click Not encoded request
If you have cookies blocked and don't use encoded url, then the server can't identify you.
>How to unblock cookies again so that gmail works. what is the default option i have to click back
( is it is ---->Allow local data to be set (recommended
Yes
Or click on that cookie icon that I described in my last comment.
>experts exchanges works fine even after blocking cookies)
Isn't the cookie for experts-exchange already stored ?
I think blocking cookies means that no new ones will be accepted.
ASKER
I see since server cannot identify
Integer count = (Integer)session.getAttrib
if(count==null)count = new Integer(0);
session.setAttribute("coun
Count increment not happening since session.setAttribute is not updating with new incremented count right?
Integer count = (Integer)session.getAttrib
if(count==null)count = new Integer(0);
session.setAttribute("coun
Count increment not happening since session.setAttribute is not updating with new incremented count right?
>Count increment not happening since session.setAttribute is not updating with new incremented count right?
Wrong.
A JSP creates a session by default. If a request is sent without a session id, then a new session will be created. Keep your eye on the session id.
Let's take the code step by step.
In the lower part of the JSP we have
Therefore the value of the "scripting variable" count is written to the response.
Next in the scriptlet we have
Here we have set the session attribute "count" to 1. But, we don't use that value until the next request and the page executes
count =1
I guess I should have defined count as the number of requests that the user has made since joining the session. What do you think?
Wrong.
A JSP creates a session by default. If a request is sent without a session id, then a new session will be created. Keep your eye on the session id.
Let's take the code step by step.
session.getAttribute("count") Integer count = (Integer)session.getAttribute("count");if(count==null)count = new Integer(0);In the lower part of the JSP we have
count=<%=count%>Therefore the value of the "scripting variable" count is written to the response.
Next in the scriptlet we have
session.setAttribute("count",new Integer(count.intValue() + 1));Here we have set the session attribute "count" to 1. But, we don't use that value until the next request and the page executes
Integer count = (Integer)session.getAttribute("count");count=<%=count%>count =1
I guess I should have defined count as the number of requests that the user has made since joining the session. What do you think?
ASKER
I agree it should have been better with noOfRequests etc rather than count.
String path = request.getContextPath() + request.getServletPath();
String encodedPath = response.encodeURL(path);
What is patha dnwhat is encodedPath. How they are related in this context
String path = request.getContextPath() + request.getServletPath();
String encodedPath = response.encodeURL(path);
What is patha dnwhat is encodedPath. How they are related in this context
>What is patha dnwhat is encodedPath.
path is another name for url. In your case it was
/CookiesProject/NewFile.js
This is what as known as a relative path. It begins with a "/" therefore the browser interprets it as relative to the server.
encodedPath is the path encoded with session id. In your case it would look like
/CookiesProject/NewFile.js
>How they are related in this context
I needed a path in order to construct the links at the bottom of the JSP.
>request.getContextPath() + request.getServletPath();
In order for you to begin to understand code, you must start reading the API.
http://docs.oracle.com/javaee/7/api/overview-summary.html
more specifically for this discussion
http://docs.oracle.com/javaee/7/api/javax/servlet/http/HttpServletRequest.html
http://docs.oracle.com/javaee/7/api/javax/servlet/http/HttpSession.html
path is another name for url. In your case it was
/CookiesProject/NewFile.js
This is what as known as a relative path. It begins with a "/" therefore the browser interprets it as relative to the server.
encodedPath is the path encoded with session id. In your case it would look like
/CookiesProject/NewFile.js
>How they are related in this context
I needed a path in order to construct the links at the bottom of the JSP.
>request.getContextPath() + request.getServletPath();
In order for you to begin to understand code, you must start reading the API.
http://docs.oracle.com/javaee/7/api/overview-summary.html
more specifically for this discussion
http://docs.oracle.com/javaee/7/api/javax/servlet/http/HttpServletRequest.html
http://docs.oracle.com/javaee/7/api/javax/servlet/http/HttpSession.html
ASKER
Makes more sense.
How did you tell code not to use until next request and page executes?
Please advice
Here we have set the session attribute "count" to 1. But, we don't use that value until the next request and the page executes
Integer count = (Integer)session.getAttribute("count ");
How did you tell code not to use until next request and page executes?
Please advice
>How did you tell code not to use until next request and page executes? Please advice
That is the way I chose to write the code.
The session-scoped variable is the following
I just used the session-scoped variable to store the value. This way it was available for multiple requests from the user.
I guess it is confusing that I used the same name for the scripting variable and the session-scoped variable. But once you learn how to read the code, it would perfectly clear. Look at
http://javapapers.com/jsp/explain-the-scope-of-jsp-objects/
http://strutscr.uw.hu/0059.html
http://hscripts.com/tutorials/jsp/jsp-scopes.php
http://www.java-samples.com/showtutorial.php?tutorialid=1009
That is the way I chose to write the code.
count=<%=count%> this is the scripting variableThe session-scoped variable is the following
session.getAttribute("count")count=${count} this is the scoped variableI just used the session-scoped variable to store the value. This way it was available for multiple requests from the user.
I guess it is confusing that I used the same name for the scripting variable and the session-scoped variable. But once you learn how to read the code, it would perfectly clear. Look at
http://javapapers.com/jsp/explain-the-scope-of-jsp-objects/
http://strutscr.uw.hu/0059.html
http://hscripts.com/tutorials/jsp/jsp-scopes.php
http://www.java-samples.com/showtutorial.php?tutorialid=1009
ASKER
I guess it is confusing that I used the same name for the scripting variable and the session-scoped variable.
can you please send the code by renaming them so that i can analyze whole code and understand based on the info and link you sent
Ok. Here is my rewrite. Please tell me if there is anything I could change to make it more clear.
<%
String url = request.getContextPath() + request.getServletPath();
String encodedURL = response.encodeURL(url);
if(session.getAttribute("numberOfRequests") == null)session.setAttribute("numberOfRequests", 0);
session.setAttribute("numberOfRequests", (Integer)session.getAttribute("numberOfRequests") + 1);
%>
The session id is ${pageContext.session.id}<br/>
Is the session new? ${pageContext.session['new']}<br/>
Did the client send the session id in the url? ${pageContext.request.requestedSessionIdFromURL}<br/>
Did the client send the session id in a cookie? ${pageContext.request.requestedSessionIdFromCookie}<br/>
URL of this page is <%=url%><br/>
Encoded URL is <%=encodedURL%> <br/>
Number of requests in this session is ${numberOfRequests}<br/>
Use the links below to refresh this page.<br/>
<a href="<%=url%>">Not encoded request</a> <a href="<%=encodedURL%>">Encoded request</a>ASKER
Line1: if(session.getAttribute("n
Line2: session.setAttribute("numb
in above two lines there is no relation between line 1 and line 2 right. Is there is any relation like If session.getAttribute("numb
Please advice
Line2: session.setAttribute("numb
in above two lines there is no relation between line 1 and line 2 right. Is there is any relation like If session.getAttribute("numb
Please advice
you cannot add 1 to a NULL.
So the only thing the first line is doing is checking for a NULL, and if it is equal to NULL it sets it to zero.
Then on the second line, it increments it by 1.
If you removed the first line, it is possible you could be trying to add 1 to NULL.
So the only thing the first line is doing is checking for a NULL, and if it is equal to NULL it sets it to zero.
Then on the second line, it increments it by 1.
If you removed the first line, it is possible you could be trying to add 1 to NULL.
ASKER
so Line1 and Line2 are independent of each other. As the program continues to execute it goes through line by line like Line1 and then Line2 right. It is basically not like IF ELSEIF kind of conditional statement right?
correct.
ASKER
To completely understand this program completerly i need to brush up some JSP skills from the links, info provided. I will get bak
>in above two lines there is no relation between line 1 and line 2 right.
Right.
>Is there is any relation like If session.getAttribute("numb
No relation or condition. I did not use the keyword else.
If the session is new, then there can't be any attributes set yet. So, my fourth line(your line 1) creates and sets the attribute to 0.
My fifth line(your line2) always increments the attribute.
Right.
>Is there is any relation like If session.getAttribute("numb
No relation or condition. I did not use the keyword else.
If the session is new, then there can't be any attributes set yet. So, my fourth line(your line 1) creates and sets the attribute to 0.
My fifth line(your line2) always increments the attribute.
i need to brush up some JSP skills
When you look at the code here... the fact that it is enclosed in "<%" and "%>" that tells you that the enclosed code is javascript.
So the formatting of the if (cond) expression; that you were asking about was concerning the syntax of javascript... not so much JSP's.
Ken,
Just one small correction to what you said above... The code in the JSP is actually Java (not JavaScript).
Just one small correction to what you said above... The code in the JSP is actually Java (not JavaScript).
whoops!... thanks! ;)
ASKER
I ran latest jsp.
I got output like this
The session id is 7CD8CF34DC876CED28DE0F69FC
Is the session new? false
Did the client send the session id in the url? false
Did the client send the session id in a cookie? true
URL of this page is /CookiesProject/NewFile2.j
Encoded URL is /CookiesProject/NewFile2.j
Number of requests in this session is 17
Use the links below to refresh this page.
Not encoded request Encoded request
wheni click the Encoded Request link multiple times. It makes sense to me as i have not disabled cookies session tracking is being done using cookies mechanism rather than url rewriting.
I have one question. why both below URLs printing the same
URL of this page is /CookiesProject/NewFile2.j
Encoded URL is /CookiesProject/NewFile2.j
Please advice
I got output like this
The session id is 7CD8CF34DC876CED28DE0F69FC
Is the session new? false
Did the client send the session id in the url? false
Did the client send the session id in a cookie? true
URL of this page is /CookiesProject/NewFile2.j
Encoded URL is /CookiesProject/NewFile2.j
Number of requests in this session is 17
Use the links below to refresh this page.
Not encoded request Encoded request
wheni click the Encoded Request link multiple times. It makes sense to me as i have not disabled cookies session tracking is being done using cookies mechanism rather than url rewriting.
I have one question. why both below URLs printing the same
URL of this page is /CookiesProject/NewFile2.j
Encoded URL is /CookiesProject/NewFile2.j
Please advice
URL encoding will take special characters (most of the time -- blanks) and convert the to hex.
if your URL were : /My Cookie Project/New File2.jsp
your encoded URL might be : /My%20Cookie%Project/New%2
but you didn't have any special characters in your URL that needed encoding.
if your URL were : /My Cookie Project/New File2.jsp
your encoded URL might be : /My%20Cookie%Project/New%2
but you didn't have any special characters in your URL that needed encoding.
ASKER
All that we are majorly doing in this jsp is to check if session tracking is done via cookies or URL rewriting
Then print count of number of visits in current session right.
Then print count of number of visits in current session right.
ASKER CERTIFIED SOLUTION
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@Ken Butters,
You are talking about HTML form encoding. Look at
http://docs.oracle.com/javase/7/docs/api/java/net/URLEncoder.html
You are talking about HTML form encoding. Look at
http://docs.oracle.com/javase/7/docs/api/java/net/URLEncoder.html
ASKER
The first response will show the session id in the "EncodedURL"
Yea, I remember now I tested as you mentioned by disabling cookies and got the encoded url with the session id as well as below
The session id is F280FB1A8371400F1459DE04E9
Is the session new? true
Did the client send the session id in the url? false
Did the client send the session id in a cookie? false
path is /CookiesProject/NewFile.js
encodedPath is /CookiesProject/NewFile.js
count=0
Not encoded request
Encoded request
ASKER
I am not clear how session can be maintained across multiple connections. I thought session is specific to let us say one online user say John while he is accessing shopping cart let us say in amazon for his particular internet connection. Please advise.