Application & Session variables

how to store & use Application & Session variables in Seervlets & JSPs

Hi
how to store & use Application & Session variables in JSPSee: http://developer.java.sun.com/developer/onlineTraining/JSPIntro/contents.html
how to store & use Application & Session variables in ServletsSee:
http://java.sun.com/docs/books/tutorial/servlets/communication/attributes.html
Good Luck!
Eshwar Rao
Developer Technical Support
Sun microsystems inc.
http://www.sun.com/developers/support

Similar Messages

Flashbuilder and Cold Fusion (using application/session variables)

I would like to know if anybody uses Flashbuilder with Cold Fusion?
Since Cold Fusion has lots of different scopes of variables (application, session, client, form, url, etc...) how do you manage this in Flex/Flashbuilder?
Are there forums or groups specifically for using Flex3/Flashbuilder with backend server side technologies such as Cold Fusion?.
The only server side technology that I have interest in is Cold Fusion. I've seen basic tutorials and videos using Cold Fusion CFC's and data binding with Flex. I haven't seen or heard anything using a Cold Fusion application, session, or client variable in Flex.
Hopefully some of you have some experience on this topic.
Thanks

hey popster,
i too had this question some time ago. my entire app was built on CF with HTML before i started integrating Flex 3 with it. i found that i needed to create cookie variables for all my session variables i was using in order to maintain and remember who the user was in my CFC calls. i also found that after i compiled a flex app, i changed the .html to .cfm (the file that loads the compiled SWF file). by doing this i was able to pass CF session variables into the flex app and you can refer to these anywhere in Flex by using Application.application.parameters.{variable name here}
add the CF variable in the FlashVars line to pass it into Flex (see the last line of code). this will create a variable (in my case i'm passing session.employeenumber). then in your flex app you can reference it by using Application.application.parameters.emplid:
AC_FL_RunContent(
 "src", "Request",
 "width", "100%",
 "height", "87%",
 "align", "middle",
 "id", "Request",
 "quality", "high",
 "bgcolor", "#869ca7",
 "name", "Request",
 "allowScriptAccess","sameDomain",
 "type", "application/x-shockwave-flash",
 "pluginspage", "http://www.adobe.com/go/getflashplayer",
 "wmode","transparent",
 "FlashVars","emplid=<cfoutput>#session.employeenumber#</cfoutput"
A little trick I learned (does Adobe really expect us to re-engineer how our apps have been working by no longer using sessions for Flex?). Then in your CFCs if you also create cookies for every session variable you can maintain the variables based on user login. HOPE THIS HELPS!
-Matt

Unable to fetch session variables in my application page code behind

hi,
my env: 1 WFE server which hosts the central admin and my web appln, 1 sql server box
i am having a custom web part[ listviewbyquery web part] which populates the site collection/ sub site's document library contents . also it reads some query string values and pushes these values into session variables.
and i am having another application page in this application which reads this session variables and perform some operation in a custom sql db. But i am unable to read these session variables on page load of this application page.
am unable to debug also. so, would like to know is there any way i can see, what values are getting passed to this page and verify the session variables are accessed correctly.
or
is this by design, that its not possible to read session variables in the application page ?
if i am not having a visual studio env. to debug, how to test these session variable existence / to find the root cause of this issue.
note: already configured session state in IIS , http modules section. am using Page.Session["myvariable1"].tostring() to fetch the session variables.
help is appreciated!

i have found out myself. i have put page.response.write(mysessionvariables) in the code and deployed and tested in my env. and i was able to find out the reason and i have fixed it with proper validation check.

Passing values to session variables from another application

Hi,
From an external application we are passing username and password for accessing the OBIEE Dashboard.In the url call we are passing NQUser and NQPassword. This is working fine.
To setup data level security we need to pass region id list also as request object. Then we can filter the tables by the value in the region id list for that user. If we use external table to pass the home_id list then the application is working fine by setting up row-wise init block. But we need request object from an external application to send the list. How can we accept the list from OBIEE RPD?
In the documentation it mentions about session variables - non system. But it requires an init block. How can we create a variable that accepts the values when user logins just like NQUser and NQPassword.
Please suggest.
Thanks.

Try this ...
http://oraclebizint.wordpress.com/2007/07/30/customizing-obi-ee-%E2%80%93-go-url-parameters/
In this blog entry you'll find at the bottom ...
Hello, Can you please explain how to pass parameter values in the url. For example, I want to run an answers query and pass into the url something like this: &Region=West
Venkatakrishnan J Says:
August 22, 2007 at 7:36 am
Yes, this absolutely possible. You can get the details from the Web Services guide since it has all the necessary examples and more explanation. Thats why i did not include it in the blog. You can get it from page 213 of the Docs http://download.oracle.com/docs/cd/B40078_02/doc/bi.1013/b31766.pdf

Application.cfm - Should I use queries or set session variables?

Hi,
I have an application that has many users for many different
companies logged in at the same time using the system. I use the
application.cfm to call and set a bunch of variables that make the
system work, such as preferences and things. Would it be better to
use 5 or 6 queries all pulling one record, or call the queries only
once at the start of the session and set 30 to 50 session variables
based on the query results? Which method would bog the system down
less? It seems that session variables use quite a bit of memory.
I'm just trying to get the "simple answer" for this, if that's even
possible.
Please let me know your thoughts and experience on this.
Thanks much,
Jeff W!

In order to give you a simple "do it this way" answer, more
information is needed.
How long does it take to run those 5-6 queries on each
request? How many users are logged in at peak times? How much data
would you be storing in the session for each user? How much RAM do
you have on your server?
On one application, we've decided to go the session variable
route. The size for each users' session maxes out at 2.5 KB. We
have 512 MB dedicated to CF, but can easily scale up on the
hardware we have to 1.5 GB or more. At 512 MB, 2.5 KB per user
session, we can handle a little over 200,000 concurrent users
(assuming all CF memory could be utilized for session variables,
which isn't true). There are only 6,000 users total in our system,
so we have quite a bit of headroom.
Are you on CF8? If so, open up the server monitor, start
monitoring, profiling, and memory tracking, and log in with a
couple users (with your code setup to store all that info in the
session). See how much storage each session takes. Then look at
your server. How much RAM do you have? what do you currently have
allocated to ColdFusion? What's your peak concurrent user level? Do
you have headroom? Also, see if the benefits of storing it in the
session are even worth it (how long do those 5-6 queries add to
each requst?)

Javacard and session variables

Hello,
I'm trying to find a reasonable Javacard technique to handle "session variables" that must be kept between successive APDUs, but must be re-initialized on each card reset (and/or each time the application is selected); e.g. currently selected file, currently selected record, current session key, has the user PIN been verified...
Such variables are best held in RAM, since changing permanent (EEPROM or Flash) variables is so slow (and in the long run limiting the operational life of the card).
Examples in the Java Card Kit 2.2.2 (e.g. JavaPurseCrypto.java) manipulate session variables in the following way:
1) The programmers group session variables of basic type (Short, Byte, Boolean) according to type, and map each such variable at an explicit index of a vector (one per basic type used as session variable).
2) At install() time, each such vector, and each vector session variable, is explicitly allocated as a transient object, and this object is stored in a field of the application (in permanent memory), where it remains across resets.
3) Each use of a session variable of basic type is explicitly translated by the programmer into using the appropriately numbered element of the appropriate vector.
4) Vector session variables require no further syntactic juggling, but eat up an object descriptor worth of permanent data memory (EEPROM or Flash), and a function call + object affectation worth of applet-storage memory (EEPROM, Flash or ROM).
The preparatory phase goes:
public class MyApp extends Applet {
// transientShorts array indices
    final static byte      TN_IX = 0;
    final static byte      NEW_BALANCE_IX=(byte)TN_IX+1;
    final static byte      CURRENT_BALANCE_IX=(byte)NEW_BALANCE_IX+1;
    final static byte      AMOUNT_IX=(byte)CURRENT_BALANCE_IX+1;
    final static byte   TRANSACTION_TYPE_IX=(byte)AMOUNT_IX+1;
    final static byte     SELECTED_FILE_IX=(byte)TRANSACTION_TYPE_IX+1;
    final static byte   NUM_TRANSIENT_SHORTS=(byte)SELECTED_FILE_IX+1;
// transientBools array indices
    final static byte      TRANSACTION_INITIALIZED=0;
    final static byte      UPDATE_INITIALIZED=(byte)TRANSACTION_INITIALIZED+1;
    final static byte   NUM_TRANSIENT_BOOLS=(byte)UPDATE_INITIALIZED+1;
// remanent variables holding reference for transient variables
    private short[]     transientShorts;
    private boolean[]   transientBools;
    private byte[]      CAD_ID_array;
    private byte[]      byteArray8; // Signature work array
// install method
    public static void install( byte[] bArray, short bOffset, byte bLength ) {
         //Create transient objects.
        transientShorts = JCSystem.makeTransientShortArray( NUM_TRANSIENT_SHORTS,
            JCSystem.CLEAR_ON_DESELECT);
        transientBools = JCSystem.makeTransientBooleanArray( NUM_TRANSIENT_BOOLS,
            JCSystem.CLEAR_ON_DESELECT);
        CAD_ID_array = JCSystem.makeTransientByteArray( (short)4,
            JCSystem.CLEAR_ON_DESELECT);
        byteArray8 = JCSystem.makeTransientByteArray( (short)8,
            JCSystem.CLEAR_ON_DESELECT);
(..)and when it's time for usage, things go:
    if (transientShorts[SELECTED_FILE_IX] == (short)0)
        transientShorts[SELECTED_FILE_IX] == fid;
    transientBools[UPDATE_INITIALIZED] =
        sig.verify(MAC_buffer, (short)0, (short)10,
            byteArray8, START, SIGNATURE_LENGTH);I find this
a) Verbose and complex.
b) Error-prone: there is nothing to prevent the accidental use of transientShorts[UPDATE_INITIALIZED].
c) Wastefull of memory: each use of a basic-type state variable wastes some code; each vector state variable wastes an object-descriptor worth of permanent data memory, and code for its allocation.
d) Slow at runtime: each use of a "session variable", especially of a basic type, goes thru method invocation(s) which end up painfully slow (at least on some cards), to the point that for repeated uses, one often attain a nice speedup by caching a session variable, and/or transientShorts and the like, into local variables.
As an aside, I don't get if the true allocation of RAM occurs at install time (implying non-selected applications eat up RAM), or at application selection (implying hidden extra overhead).
I dream of an equivalent for the C idiom "struct of state variables". Are these issues discussed, in a Sun manual, or elsewhere? Is there a better way?
Other desperate questions: does a C compiler that output Javacard bytecode make sense/exists? Or a usable Javacard bytecode assembler?
Francois Grieu

Interesting post.
I don't have a solution to your problem, but caching the session variables arrays in local variable arrays is a good start. This should be only done when the applet is in context, e.g. selected or accessed through the shareable interface. This values should be written back to EEPROM at e.g. deselect or some other important point of time. Do you run into problems if a tear happens? I don't think so since the session variables should be transactional, and a defined point will commit a transaction.
Analyzing the bytecode is a good idea. I know of a view in JCOP Tools (Eclipse plugin) where you can analyze the bytecode and optimize it to your needs.

Using Session Variables for User Login - sometimes they don't persist... what am I doing wrong?

Hi all,
I'm running a site that requires user login. I approached the building of this site as almost a complete newb to CF (and dynamic coding in general), and it's been a great learing experience (with lots of help from you guys).
However, I guess I never learned the correct way to handle a user login. It seemed to me that I could just test the user-entered credentials against those stored in a database, then set a session variable containg that user's record number. Then, not only would I have an easy way of knowing who this user was and therefore what info to serve him, but I could test for the existence of a valid login on every page in the protected folder, by adding this code to my application.cfc in that folder:
<cfset This.Sessionmanagement=true>
<cfset This.Sessiontimeout="#createtimespan(0,8,0,0)#">
 <cfif NOT isDefined ("session.username") or NOT isDefined ("session.password") or NOT isDefined ("session.storeID")>
 <cflocation url="../index.cfm" addtoken="no">
 </cfif>
...and it goes on to run a query and verify that the session.username and session.password match for the store defined by session.storeID. If not, all session variables are cleared and it bounces you back to the login page. When the user clicks Logout, all I do is delete all the session variables.
This seemed to work great for like a year, but lately I've been getting reports that the login doesn't seem to persist for longer than approx. 20 minutes of inactivity. You can see I specified session variables to remain active for 8 hours (I know that seems like a drastically long login, but it's what's necessary for this application). I've only gotten this report from a few people, and I myself can't seem to duplicate it... I've tested an inactive login for 45 minutes now and it held.
SO: any reason you can think of why session variables would be spontaneously clearing for some people? Would having your router reset its IP address invalidate the session or something? Also, the problem seemed to begin appearing after my host upgraded all their servers to CF9... could there be any relation?
And on a more general note... did I go about this completely the wrong way to begin with? If so, what's the standard way to manage a login?
Lots of questions, I know... thanks very much for any answers or suggestions!
Joe

Ian,
Thanks very much - very helpful information.
Sounds like passing the tokens in every request is probably the way to go for this. I don't think it's likely that any users will be sharing links, unless they actually intend for the recipient to see their info anyway.
Is that all I would have to do, is add the tokens to every path? Would that guarantee that all the session variables would remain valid until timeout or being cleared?
Again, thanks, you've been really helpful.
Joe
On Jun 23, 2010 4:37 PM, Ian Skinner <[email protected]> wrote:
Unfortunately this is the nature of HTTP web applications. There is NO state maintained from HTTP request to request. This is by design in the HTTP protocol specifications.
ColdFusion provides two methods to circumvent this limitation. Each method has limitations and caveats. They both rely on the passing of tokens between the client and the server with every request. These tokens can be passed as cookies OR URL (GET) variables. You are using the cookie method, which is the simpler and most common. You may be experiencing the limitation of this method. If something happens to the cookies the session can be lost.
You could pass the (CFID & CFTOKEN) OR JESSIONID tokens through the URL query string with every request. This requires one to add these values to every link, form action, cflocation or other request path in our application. ColdFusion provides the session.urltoken variable to make this easier to do. The tokens will be visible to the user. Also if the links with an individual token is share with other users, via e-mail, chat, social networks, etc and one of these users utilize the link during the life of a session (8 hours apparently in your case). Then that user will access the session of the original user.
Cookie session management is by far the most common choice by CF developers. If these methods do not meet your needs you would need to go beyond the HTTP limitations of web applications. One might be able to accomplish this with a Flex|Air|Flash applications that can be configured to use a continuous connection to the server. Thus not suffer the stateless nature of the normal HTTP request-response cycle.
I do not know if a router resetting would cause cookies to be discarded or otherwise invalidated. But I would not think it is beyond the relm of possibilities.

Session Variable? -How do I treat this

Hello,
I am writing an application that is tracking the results
arriving from various selected stations (230 of them). My
application will dynamically displays only stations for which
results have been received. I plan to have my page refresh every 5
minutes to update the results list.
Now based on results received I will update a report page, so
I need to set a variable that changes every time my query result
set changes and then I will pass this new value to the report page
for processing. I am confused about how to treat this variable.
Should I use set it as a cookie or a session variable? (but it
could change many times during the session)? TIA

Hi,
Your questions is not clear, so I'm not sure if this is what
you are looking for.
Let's forget for a moment how the data gets there, and let's
focus on the report.
You have a databases that get's constantly updated with
new/changing records. It's sounds to me like you need to timestamp
your data, and when the report page is opened, you need to
aggregate data from now()-5 minutes to now() and display them.
The refresh for the page every 5 minutes needs to be done
with javascript (window.setTimeout)
cheers,
fober

Placing session variable on bottom of each printed page

I have an application that contains a page in which we use as
a printed report. We plan to convert this someday to a crystal
report but for now are only option is to use the web browser as our
reporting page.
What I need is to know is if there is a way to code the page
so that the report id, which is stored as a session variable can be
printed out on either the top or bottom of each new page. The
report contains a lot of narrative, so it is impossible to tell
where the new page is going to begin and end because the length of
the narrative varies from 1 to 10 pages.
I don’t know if there is anyway to incorporate the page
setup from the browser settings, we are a state government, and we
are only using Internet Explorer 6.0 as our browser. The
application is using CF MX 7.
Any ideas??
Thanks.

I think I misunderstood. You have one long report and when
printed will be multiple pages. You need the report name to be on
each page.
Three ways I can think of to do it.
First you can use the <title></title> to your
advantage. When printing from a browser the title is at the top of
each page. (though this can be turned off under browser options but
is on by default if I remember correctly).
<head>
<cfset report_name = "Dynamic Report Name">
<title><cfoutput>#report_name#</cfoutput></title>
</head>
Second, you can make the report name part of the URL so it
will appear at the bottom of each page.(this can be turned off too
in browsers)
www.mysite.com/reports/rpt_gen.cfm?REPORT_NAME=AGENT_MULDER_EXPENSE_REPORT_2005
Third, use an image as a watermark. You should probably make
the image 1/2 the height of the printed page. The background image
repeats. That way, you are sure it will appear somewhere on each
page printed. Width is another problem. But you may be able to
center the background image horizontally using css.
<body BACKGROUND="images/report_proof_background.jpg" >
* You might also want to check out using css with page
breaks.

Unable to filter a recordset using a session variable

I have a volunteer application page and when the volunteer presses <Submit> their info is saved in a MySQl db table and a session variable is created containing the primary key of their record in the table, control is then passed to a "success page". The success page can access the session variable (I proved this by displaying the session variable on the success page) so my next step was to create a recordset in the success page with a filter using the session variable to select the appropriate row in the table, allowing me to display to the volunteer the info they submitted.
I set up a test success page which displays the session variable and one field of the volunteer info. When I test this I see the session variable displayed but the corresponding volunteer info field from the recordset is not displayed.
The volunteer application page is here www.hollisterairshow.com/volunteerapp.php and the successpage is here www.hollisterairshow.com/thanksvol.php
The code that creates the session variable in the volunteer application page is shown below
$_SESSION['volunteer_id'] = mysql_insert_id();
The code to display the session variable in the success page is shown below
<?php echo $_SESSION['volunteer_id']; ?>
The code to display the volunteer info is shown below
<h1> Thank You <?php echo $row_rsVolunteerApp['firstname']; ?>!! </h1>
The recordset definition is shown below
The success page test result is shown below, as you can see the volunteer's first name is not displayed immediately after the "Thank you" message but the session variable holding the correct primary key (41) is shown correctly.
Does anyone have an idea of what I'm doing wrong?
Thanks
Tony

Where did you put session_start()? It needs to be before the variable is accessed. It's obviously before the line that displays the value in your page, but is it before the SQL query is generated?
Also, have you checked in phpMyAdmin to see whether volunteernumber 41 has any values in the database?

Help Needed in checking session variable

In a sample site, I am calling a bounded task flow from an unbounded task flow. In the called taskflow the default activity is a router which checks the session variable, and the home page will be loaded only if the session variable is not null. If session variable is null router will lead to a page dispalying 'session expired'. But even after clearing the session if I copy pasted the previous url, the home page is loading. But when I call bounded taskflow from a bounded taskflow, it is working fine. Can anyone suggest any solution? Thanks in advance

Thanks for the reply. I'm using jdev 11.1.1.5.0.. I'm just trying with a sample example. I have a login page and when the user logins, the user name is stored in session. the loginpage view activity is in adfc config unbounded taskflow. The login credentials is validated in a backing bean and based on the return value, if the login is valid, a bounded taskflow 'hometaskflow' is called. In this bounded taskflow, the default activity is a router wchich checks the username stored in session. If the username is not null it will lead to the 'homepage' view. Else if it is null it will lead to a 'sessionexpired' view.
In the java class of login page I'm accessing the session variable as shown
public Username getSessionBean()
Username username =
(Username)resolveExpression("#{Username}");
return username;
public static Object resolveExpression(String expression)
FacesContext facesContext = FacesContext.getCurrentInstance();
Application app = facesContext.getApplication();
ExpressionFactory elFactory = app.getExpressionFactory();
ELContext elContext = facesContext.getELContext();
ValueExpression valueExp =
elFactory.createValueExpression(elContext, expression,
Object.class);
return valueExp.getValue(elContext);
On login button click the function being executed is as shown
public String onLoginClick() {
if(String.valueOf(itUserName.getValue()).equals("admin")
&& String.valueOf(itPassword.getValue()).equals("admin"))
Username username=getSessionBean();
username.setUsername(itUserName.getValue().toString());
return "success";
else {
return "invalid";
And to set username as null on logout, I used this function on logout click
public void clearSession()
Username username=getSessionBean();
username.setUsername(null);
The EL expression used to check the value of session variable is
#{sessionScope.Username.username==null} outcome is expired
#{sessionScope.Username.username!=null} outcome is active
This worked when I used in a bounded taskflow, which is being called from another bounded taskflow. But not working in this scenario...

How to use session variable in JSP function & How to use both JSP Servlet

Hi,
I am new to JSP and servlets
Still I am devloping a website in JSP. I am not mixing JSP with servlets, but I do create Java files for bean, logic and database works.
I try to keep the hard coding part out of JSP.
I dont how to use both JSP and Servlets in combination.
Hence If needed I write some functions in JSP.
but it gives me error
+<%! public void abc()+
+{+
int intUserId = Integer.valueOf((Integer) session.getAttribute("MySession_UserID"));
+}+
+%>+
Saying cannot find symbol session
1) So can u please tell how can I access session variables within JSP function
2) And also give me some links/tutorials about useing both JSP and Servlets in combination.
Thanks
Venkat

The application architecture when you use Servlets and JSP in a standard MVC pattern is explained here (under the heading "Integrating Servlets and JSP Pages") and here ...

How to pass a session variable to the bussines layer?

Hello,
I am doing a management application, and I need to store the login user that make insertions on any table, and the pages does not has backing beans.
I had try to do that bindding the value field of a hidden attribute with the session variable, but it only change the value of the one. My second attempt was make an javascript function to do that on the page´s load, but it not looks like a good solution.
Someone knows a way to sent the session value to the bussines layer? O a way to access from the Bussines layer to the session?
Thanks
Tony


Hi,


Another solution (that I always use) is storing simultaneously the same data in HttpSession (in view layer) and session hashtable (in businness layer).


You can put and get these data in any businness component using following methods:



private void setToJboSession(String key, Object val){
 Hashtable userData = getDBTransaction().getSession().getUserData();
if (userData == null) {
userData = new Hashtable();
userData.put(key, val);
}


and



private Object getFromJboSession(String key){
return getDBTransaction().getSession().getUserData().get(key);
}


Kuba

How to create a session variable in Apex?

Hello colleagues,
Is there someone do know how to create a session variable in Apex?
How to get them?
Thanks
Best Regards

Hello,
What do you mean by 'session variable'? You mean something that stores the value int he users session state?
I really recommend reading the 2-Day Developer guide documentation, there is a complete section on session state -
http://download.oracle.com/docs/cd/E10513_01/doc/appdev.310/e10499/concept.htm#CIHCFHBD
Hope this helps,
John
Blog: http://jes.blogs.shellprompt.net
Work: http://www.apex-evangelists.com
Author of Pro Application Express: http://tinyurl.com/3gu7cd

Page Specific Persistence using Session Variables

Hi, I have read a lot about using session variables to persist the ReportDocument object across page loads. This works fine if you have just one page open with one report. The problem I am having is I have a web application that makes 30 or 40 different reports available to the user. To simplify the code and make it easier to add new reports I have developed a single template aspx page that can be used to view any of the reports.
My problem is that if the user opens 2 different reports in 2 separate tabs in the browser then the session variable persistence doesn't work because the session variable is available to both tabs.
Is there a way to persist the ReportDocument object which is 'page' specific.
Thanks

Your best option is likely to have something that makes the session variable names unique. I've done such things as putting the current datetime in the url as a querystring parameter and appending that to the variable name. On each postback that querystring should persist.
You might be able to use the reportclientdocument object and serialize the report and persist through view state, haven't tried this with inproc ras though. A sample that uses the ras sdk can be found [here|http://wiki.sdn.sap.com/wiki/display/BOBJ/NETRASSDK+Samples]

Application & Session variables

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