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From "Gerhard Petracek (JIRA)" <...@myfaces.apache.org>
Subject [jira] [Commented] (EXTCDI-316) Close window context view leakge - JSF 2.1 Multiple Iframes per page
Date Tue, 16 Sep 2014 21:28:34 GMT

    [ https://issues.apache.org/jira/browse/EXTCDI-316?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14136267#comment-14136267
] 

Gerhard Petracek commented on EXTCDI-316:
-----------------------------------------

#1 if your view-state leaks, it's the first indication that your approach is just not correct
for jsf.
#2 codi doesn't support multiple logical pages per physical page (per default). however, you
can provide your own approach with a custom org.apache.myfaces.extensions.cdi.jsf.impl.scope.conversation.spi.WindowHandler
#3 the number of windows (per user-session) is restricted by WindowContextConfig#getMaxWindowContextCount
- per default 64 windows per session are allowed. -> the eldest window in the session gets
closed to get a free slot for the new window. you can change this default (just provide a
specialized WindowContextConfig or implement a custom WindowContextQuotaHandler).

> Close window context view leakge - JSF 2.1 Multiple Iframes per page
> --------------------------------------------------------------------
>
>                 Key: EXTCDI-316
>                 URL: https://issues.apache.org/jira/browse/EXTCDI-316
>             Project: MyFaces CODI
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 1.0.3
>         Environment: Oracle GlassFish Server 3.1.2.5 (build 2), jdk1.6.0_45
>            Reporter: Nuno G. de M
>   Original Estimate: 72h
>  Remaining Estimate: 72h
>
> Hi, and thank you for your support.
> First, I would just like to stat that I am unsure if the "issue" detected in our application
is a real issue within CODI, or if it is we that are misusing the framework. Therefore, I
would be happy to get your input on the issue I am about to detail.
> ISSUE SUMMARY:
> - we have a ui architecture comprised by several Iframes within a main page, where each
iframe has its own CODI window context. After several clicks replacing the content that of
a targetIfram by new content, we were having CODI view context leakage as well as JSF view
state leakage.
> ISSUE DETAILS:
> For historical as well performance reasons reasons, we have a UI that is composed into
several IFrames within a parent portal iframe. This decomposing of the view into sub-views
means the JSF context to serialize-deserialize per iframe/.xhtml present in the UI is smaller.
As opposed to a single big-ui view state.
> An overview of the core iframes invovled would be:
> (1) window.top - Contains the Header and a left-side navigation menu
> (2) window.top.contentIfram - Iframe Contains your typical page conent (.xhtml)
> (3) window.top.footer - iframe containing a dynamic footer (its own .xhtml)
> (4) wintow.top.applet - Iframe that includes an applet
> (5) window.top.special - an  auxiliary .xhtml that complements the applet data
> (6) window.top.clean - iframe that contains an .xhtml to do CODI window context and JSF
sever state cleanup (created to deal with the issue being explained here)
> The BUG in view navigation is the following:
> Each time the user interacts with the UI, e.g by clicing on an menu command button, or
on a applet view element, prompting for a new .xhtml view to be loaded and replace the old
.xhtml loaded on a target iframe we leak both a JSF and CODI window context.
> Our steps are the following:
> (1) we change the src of the iframe to point to the new view to be loaded
> e.g iframe.src = 'urlTonewPageToBeLoaded.xhtml?requestViewParameters'
> In this request we do not inclode the old windowId of the iframe being replaced. Meaning
codi will have to create a new view ID for this new page load.
> (2) We also trigger an ajax request to server to have the old codi window context being
closed.
> Intially here did:
> (2.1)WindowContext wContext =  windowContextManager.getWindowContext('windowIdToClose);
> wContext.close()
> It turns out that as we did these two steps we had two leakages.
> After about 64 clicks on the applet, if we interatcted with views that the applet had
been loading we would have no issues. If we clicked on  some of the older views that had been
loaded after the login and not interacted with since then (e.g. the footer) we would have
a view timeout exception.
> This happened because with each new iframe.src='newView', CODI was not cleaning up its
window context map, namely the following line:
>   this.windowContextMap.remove(editableWindowContext.getId());
> is not executed during a WindowContext.close().
> So despite our class to close the window context, the map would continue to hold the
view just closed. After 64 clicks the view uffer of CODI would be totally populated, and each
new click was destroying the one of the least recently used views. This could be the main
menu, this could be the page content or this could be the footer.
> To address this issue, we had to start injecting the EditableWindowContextManager, and
use its close API.
> So the procedure for closing a CODI window context avoiding CODI view leakge turned into
a :
>  Map<String, EditableWindowContext> existingContextIds = getExistingContextIds();
> windowContextManager.closeWindowContext(windowIdOfContextToClose);
> Finally, there was still one last view leakge to address.
> Even when we use the windowContextManager.closeWindowContext(windowIdOfContextToClose),
the JSF view state associate to this view still exists in the JSF view map.
> JSF-core (e.g majorra) seems to have a limit of 15 views within this LRU logical map.
> So once we stopped leaking views in CODI, we still had to tackle the leakage in JSF.
Meaning, when we close a CODI window context, we need to the javax.views.state string to access
the JSF map of logical views and remove them. 
>  Object sessionObj = externalContext.getSession(false);
>         synchronized (sessionObj) {
> Map logicalMap = (Map) externalContext.getSessionMap().get(LOGICAL_VIEW_MAP);
> Map actualMap = (Map) logicalMap.get(idInLogicalMap);
>                         actualMap.clear();
>                         // remove the leaked view from the LRU map of logical views
>                         logicalMap.remove(idInLogicalMap);
> }
> ------
> Naturally, an application should normally not have to dig deep into framework code. One
of the two is for sure true:
> - either we are misusing CODI to manage our views
> - or CODI  has an issue
> Thanks in advance for any input on this issue.



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