Best way to store variables and user choices in JSP page

[Vajra]

Hello everybody

I am working on a Website built on JSP and Servlets . one of the features of
the site is to give user the chance to subscribe to different newsletters
under different categories.

So for example, user1 surfs to the page which displays category sport and
under that some options (check boxes) and he can choose zero or more, and he
clicks to add the next catetory options , for example entertainement.


I am new at Java and I'd be grateful if you help me with my questions:

1. What is the best way to keep user's choices as he surfs and adds options
under each category ? I thought of using session vars , in form of arrays,
but I wonder if there is a better more efficient way ?

2. At the last page, user is shown the category names with two links beside
them , edit and remove (he will not see the individual choices under each
category) ... could you also advise what is the best way to implement this
as well? For example if I use array session vars, I am not sure how to
display that particular page again with the choices made...


From the summary page , something like this is displayed to user if he has
choices from 3 categoires of Sport , Social, Home ; but he did not choose
anything from Movies and others.:

Sport : edit (hyperlink) , remove (hyperlink)
Social : edit (hyperlink) , remove (hyperlink)
Home edit (hyperlink) , remove (hyperlink)


The user should have a choice to go back to each category page and edit it
(he will see his previous choices in check boxes), or just by clicking a
link in the final summary page, to remove it. The categories and options
under each are read from database. User's choices are not commited to DB
until he reviews the summary and clicks confirm button at the last stage.

Thank you in advance
Vajra

 

[shah.rajan]

Well first you should not be using session variables. You can use
hidden fields avaialble in html
<input type="hidden" name="" value-""> , By using hidden fields you
will be able to get all the values in each page you just need to get
all this values and store it back to the returning page.

For the last page editing thing there can be 2 ways to do it

1) Create a link in the jsp page in such a way that all the options
which they have selected goes with it

eg: Sports <a href="Test.jsp?
sports=abc,cde&social=xyz,wxy&option=edit&category=sports"> Edit </a>

2) second option is whenever the link is clicked you call a
javascript function which will do a post submit of the page and will
set a value of some variable which will tell whether it was edit or
remove and which category

Sports <a href="#" onClick="DoSomething('Edit','Sports')" > Edit </a>

<script>

function DoSomething(action , category)
{
.............

}

</script>

 

[Lew]

(e-mail address removed) wrote:

Please do not top-post.

Well first you should not be using session variables. You can use
hidden fields avaialble in html [sic]

Why not use session variables?

<input type="hidden" name="" value-""> , By using hidden fields you
will be able to get all the values in each page you just need to get
all this values and store it back to the returning page.

At the cost of increased traffic between client and server, and concomitant
security issues, which would not be a problem with session variables.

For the last page editing thing there can be 2 ways to do it

1) Create a link in the jsp page in such a way that all the options
which they have selected goes with it

eg: Sports <a href="Test.jsp?
sports=abc,cde&social=xyz,wxy&option=edit&category=sports"> Edit </a>

Generally you're better off following a Model-View-Controller pattern,
submitting a POST to a controller servlet and having it guide the response
with request parameters, rather than tangling navigation and view in this way.

2) second option is whenever the link is clicked you call a
javascript function which will do a post submit of the page and will
set a value of some variable which will tell whether it was edit or
remove and which category

Sports <a href="#" onClick="DoSomething('Edit','Sports')" > Edit </a>

<script>

Or just use an "Edit" or "Remove" submit button.

While Javascript can sweeten the user experience, it is by no means required
for this scenario.

Use "submit" inputs rather than links. Don't hit JSPs with a GET or POST;
JSPs are for view components. Hit the controller servlet. That servlet will
dispatch a RequestDispatcher.forward() to bring up the correct JSP. Google
"Model-View-Controller", Sun's "Model 2" architecture, and the "Front
Controller Pattern".

 

[shah.rajan]

(e-mail address removed) wrote:

Please do not top-post.

Well first you should not be using session variables. You can use
hidden fields avaialble in html [sic]

Why not use session variables?

<input type="hidden" name="" value-""> , By using hidden fields you
will be able to get all the values in each page you just need to get
all this values and store it back to the returning page.

At the cost of increased traffic between client and server, and concomitant
security issues, which would not be a problem with session variables.

For the last page editing thing there can be 2 ways to do it

1) Create a link in the jsp page in such a way that all the options
which they have selected goes with it

eg: Sports <a href="Test.jsp?
sports=abc,cde&social=xyz,wxy&option=edit&category=sports"> Edit </a>

Generally you're better off following a Model-View-Controller pattern,
submitting a POST to a controller servlet and having it guide the response
with request parameters, rather than tangling navigation and view in this way.

2) second option is whenever the link is clicked you call a
javascript function which will do a post submit of the page and will
set a value of some variable which will tell whether it was edit or
remove and which category

Sports <a href="#" onClick="DoSomething('Edit','Sports')" > Edit </a>

<script>

Or just use an "Edit" or "Remove" submit button.

While Javascript can sweeten the user experience, it is by no means required
for this scenario.

Use "submit" inputs rather than links. Don't hit JSPs with a GET or POST;
JSPs are for view components. Hit the controller servlet. That servlet will
dispatch a RequestDispatcher.forward() to bring up the correct JSP. Google
"Model-View-Controller", Sun's "Model 2" architecture, and the "Front
Controller Pattern".

Making session variables is a costly affair for the server. And you
should avoid using that in all the conditions. If you'r server is
having load balancing then it will be more costly for all the servers.
Here the user is going to traverse from one page to another so he does
not need to use session variables. Hidden varaibles can do the trick.
I don't think this application is passing any valuable information
like password in hidden variables which need to be secured.

If you are not using session variables then you have to send the data
by either GET or POST internally you can use MVC 2 to handle this
things

Raj

 

[vajra1987]

Thank you for the replies and explanations .... Appreciated.

Vajra

 

[Lew]

Making session variables is a costly affair for the server. And you

Making hidden variables is a costly affair for the connection.

Which cost is worse, and how are you judging that?

should avoid using that in all the conditions.

I don't think so.

If you'r server is having load balancing then it will be more costly for all the servers.

But /too/ much more costly? Not likely.

Here the user is going to traverse from one page to another so he does
not need to use session variables. Hidden varaibles can do the trick.

At a cost.

I don't think this application is passing any valuable information
like password in hidden variables which need to be secured.
So?

If you are not using session variables then you have to send the data
by either GET or POST internally you can use MVC 2 to handle this
things

What is "MVC 2"?

There is nothing wrong with session variables, properly used. If something
needs to persist between requests, one must use either a session, which
collapses all session knowledge into a single "hidden variable", the session
token, or hidden variables as you describe. You seem to have an unhealthy
fear of session variables.

One should avoid session state in a web application generally, but when one
has such state, then session variables can often be a viable solution.
(Session objects should implement Serializable, which imposes additional
responsibility on the programmer, as Serializable exposes the implementation
of a class. See Joshua Bloch's excellent book /Effective Java Programming/,
which all of us should buy.)

 

[Chris ( Val )]

(e-mail address removed) wrote:
[snip]

If you are not using sessionvariablesthen you have to send the data
by either GET or POST internally you can use MVC 2 to handle this
things

What is "MVC 2"?

According to the JavaRanch FAQ's, nothing:
http://faq.javaranch.com/java/Model1Model2MVC