Keeping state without session

[Francisco Passos <fr...@opensoft.pt>]

Hello there.

Using just the request, I've found some solutions to keeping some state
between requests. I would like these findings to be validated and if you
find any incorrections, please point them out, since I'm going to rely
heavily on these mechanisms for a large-hit application (several hundreds
of users).


Method 1 - hidden inputs
========================

One of these mechanisms is placing <h:inputHidden
value="#{myBean.property}" /> in the destination page, which will
seamlessly populate the new instance property with the value it had in the
previous page.

This requires adding one field for each value.
The values are discarded in subsequent requests to other pages, unless
they possess similar hidden inputs to be populated.

Method 2 - pageFlowScope
========================

Another method is using the pageFlowScope explicitly (for instance,
slightly modifying the getter and setter of a bean property in order to
use the pageFlowScope).

Albeit a scope, one cannot declare a managed bean to have that scope in
faces-config, which actually is not so cool.
This method requires manual retrieval and update of the variable in the
pageFlowScope.
And the values need to be discarded manually.
However, this allows for keeping context values in parallel browsing
sessions (which does not work when using session beans).

Method 3 - Dialog Framework
===========================

Finally, I've just discovered the dialog framework, but haven't yet tried
it out. If it works the way I imagine, it is pretty seamless (except for
the dialog: prefix in the actions).

However, suppose a url exists in the page which invokes a get to another
page. Is state persisted? Or is it discarded, because the flow doesn't go
through a dialog:-prefixed action? In my opinion it should be discarded in
such cases.

I can easily check this soon if no-one knows the answer to this.


That about covers what I've found. Did I misinterpret anything?
Furthermore, did I miss something?

Thanks,

Francisco Passos

Re: Keeping state without session

[Mike Kienenberger <mk...@gmail.com>]

Another possiblity is using Tomahawk's t:saveState component (or
creating your own).

It makes a request-scoped bean into a page-scope-plus bean.  It does
this by saving the state of the target into the component tree (either
using Serializable or SaveState interfaces).   Whenever the tag
appears on a page, the object will be restored when the page is
restored and saved when the page is rendered.   Thus it's ideal for
page scope (add t:saveState component with a unique id) or
page-plus-scope (add the component to multiple pages with the same
id).

If you don't want all of tomahawk, it should be easy to pull this tag
out by itself since it has no renderer and no dependencies.  If you're
using jsp, you'd probably need to copy the tld, the jsp tag handler
class, the component class, and the faces-config.xml entry.   If
you're using facelets, you can copy the component class, the
faces-config.xml entry, and create a taglib.xml entry.

http://myfaces.apache.org/tomahawk/uiSaveState.html
http://wiki.apache.org/myfaces/SaveState

On 4/12/07, Francisco Passos <fr...@opensoft.pt> wrote:
>
> Hello there.
>
> Using just the request, I've found some solutions to keeping some state
> between requests. I would like these findings to be validated and if you
> find any incorrections, please point them out, since I'm going to rely
> heavily on these mechanisms for a large-hit application (several hundreds
> of users).
>
>
> Method 1 - hidden inputs
> ========================
>
> One of these mechanisms is placing <h:inputHidden
> value="#{myBean.property}" /> in the destination page, which will
> seamlessly populate the new instance property with the value it had in the
> previous page.
>
> This requires adding one field for each value.
> The values are discarded in subsequent requests to other pages, unless
> they possess similar hidden inputs to be populated.
>
> Method 2 - pageFlowScope
> ========================
>
> Another method is using the pageFlowScope explicitly (for instance,
> slightly modifying the getter and setter of a bean property in order to
> use the pageFlowScope).
>
> Albeit a scope, one cannot declare a managed bean to have that scope in
> faces-config, which actually is not so cool.
> This method requires manual retrieval and update of the variable in the
> pageFlowScope.
> And the values need to be discarded manually.
> However, this allows for keeping context values in parallel browsing
> sessions (which does not work when using session beans).
>
> Method 3 - Dialog Framework
> ===========================
>
> Finally, I've just discovered the dialog framework, but haven't yet tried
> it out. If it works the way I imagine, it is pretty seamless (except for
> the dialog: prefix in the actions).
>
> However, suppose a url exists in the page which invokes a get to another
> page. Is state persisted? Or is it discarded, because the flow doesn't go
> through a dialog:-prefixed action? In my opinion it should be discarded in
> such cases.
>
> I can easily check this soon if no-one knows the answer to this.
>
>
> That about covers what I've found. Did I misinterpret anything?
> Furthermore, did I miss something?
>
> Thanks,
>
> Francisco Passos
>
>