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From Matthias Weßendorf (JIRA) <...@myfaces.apache.org>
Subject [jira] Resolved: (TRINIDAD-1245) High Availability Testing Support
Date Fri, 03 Oct 2008 10:44:44 GMT

     [ https://issues.apache.org/jira/browse/TRINIDAD-1245?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Matthias Weßendorf resolved TRINIDAD-1245.
------------------------------------------

       Resolution: Fixed
    Fix Version/s: 1.2.10-core
         Assignee: Matthias Weßendorf

> High Availability Testing Support
> ---------------------------------
>
>                 Key: TRINIDAD-1245
>                 URL: https://issues.apache.org/jira/browse/TRINIDAD-1245
>             Project: MyFaces Trinidad
>          Issue Type: New Feature
>          Components: Archetype
>    Affects Versions: 1.2.9-core
>         Environment: All
>            Reporter: Blake Sullivan
>            Assignee: Matthias Weßendorf
>            Priority: Minor
>             Fix For: 1.2.10-core
>
>         Attachments: Trin1245_1_2_TRUNK.patch
>
>   Original Estimate: 168h
>  Remaining Estimate: 168h
>
> Most Servlet Engines support fail over for high availability by replicating changes the
the Session state to other servers.  This requires that all of the state and substate in the
Session be Serializable.  If the state is not Serializable, the failover will fail with a
SerializationException and most likely the Session attribute key for which Serialization failed.
 This poses several problems for framework and application developers:
> 1) An actual high-availability configuration should not be necessary to test that the
framework and application is using Session state correctly
> 2) The Servlet specification requires that an exception be thrown immediately when adding
setting a non Serializable attribute on the Session when the Servlet engine is running in
high-availibility mode.  This enables the offending code to be quickly identified for simple
case, but this requires:
> a) That the server be running in such a mode, which may be a pain to configure
> b) Some Servlet engines don't implement  this feature
> 3) Knowing the offending key in the Session state is not very useful if the value of
the key is an extremely complicated structure.  In particular, determining precisely which
attribute value on which component in the component state structure used in Trinidad state
saving  is a nightmare.
> The proposal is to address the problems by:
> 1) Making it possible to run Trinidad in a mode where unserializable state content and
sets on Session attributes are detected
> 2) When a state Serialization failure is detected, more detailed failure information
regarding the component and attribute key and value that failed can be determined by rerunning
with additional, but slower settings
> In order to decrease runtime overhead, the proposal is that a System property:
> org.apache.myfaces.trinidad.CHECK_STATE_SERIALIZATION
> is used to control this behavior as this allows the behavior to be determined a class
load time.
> The behavior is controlled by passing a comma-delimited set of case-insensitive values
on the system property:
> NONE--no state serialization checks are performed (the default)
> ALL--perform all available tests (unless NONE is also specified, in which case NONE takes
precedence)
> SESSION-Wrap the Session Map returned by the ExternalContext to test that only Serializable
objects are placed in the Session Map, throwing a CastCastException if the Object is not Serializable
> TREE--aggressively attempt to serialize the component state during state saving and throw
an exception if serialization fails
> COMPONENT--aggressively attempt to serialize each component subtree's state during state
saving in order to identify the problem component (slow)
> PROPERTY--aggessively attempt to serialize each property value during state saving in
order to identify the problem property (slow)
> For high availability testing, the tester would initially start off validating the Session
and JSF state is Serializable by setting the system property to:
> -Dorg.apache.myfaces.trinidad.CHECK_STATE_SERIALIZATION=session,tree
> If a JSF state serialization is detected, the test is rerun with the component and property
flags enabled:
> -Dorg.apache.myfaces.trinidad.CHECK_STATE_SERIALIZATION=all
> Programmatic access to these flags would be on the StateUtils class:
>   /**
>    * Returns <code>true</code> if components should be checked for
>    * serializability when when generating the view's state object.
>    * <p>
>    * By default component state serialization checking is off.  It can be
>    * enabled by setting the system property
>    * <code>org.apache.myfaces.trinidad.CHECK_STATE_SERIALIZATION</code>
>    * to <code>all</code> or, more rarely, adding <code>component</code>
to the
>    * comma-separated list of serialization checks to perform.
>    * <p>
>    * As property serialization checking is expensive, it is usually
>    * only enabled after component tree serialization checking has detected
>    * a problem.  In addition, since component serialization checking only
>    * detects the problem component, it is usually combined with
>    * property state serialization checking either by specifying <code>all</code>.
>    * @return
>    * @see #checkComponentTreeStateSerialization
>    */
>   public static boolean checkComponentStateSerialization(FacesContext context)
>  
>   /**
>    * Returns <code>true</code> if the component tree should be checked for
>    * serializability when when generating the view's state object.
>    * <p>
>    * By default component tree state serialization checking is off.  It can be
>    * enabled by setting the system property
>    * <code>org.apache.myfaces.trinidad.CHECK_STATE_SERIALIZATION</code>
>    * to <code>all</code> or, more commonly, adding <code>tree</code>
to the
>    * comma-separated list of serialization checks to perform.
>    * <p>
>    * Because unserializable objects defeat fail-over, it is important to
>    * check for serializability when testing applications.  While component
>    * tree state serializability checking isn't cheap, it is much faster to
>    * initially only enable checking of the component tree and then switch
>    * to <code>all</code> testing to determine the problem component and 
>    * property when the component tree testing determines a problem.
>    * @return
>    * @see #checkComponentStateSerialization
>    */
>   public static boolean checkComponentTreeStateSerialization(FacesContext context)
>  
>   /**
>    * Returns <code>true</code> if Object written to the SessionMap should
be checked for
>    * Serializability when <code>put</code> is called.
>    * <p>
>    * Configuring this property allows this aspect of high-availability to be tested without
>    * configuring the server to run in high-availability mode.
>    * <p>
>    * By default session serialization checking is off.  It can be
>    * enabled by setting the system property
>    * <code>org.apache.myfaces.trinidad.CHECK_STATE_SERIALIZATION</code>
>    * to <code>all</code> or, more commonly, adding <code>session</code>
to the
>    * comma-separated list of serialization checks to perform.
>    * @return
>    * @see #checkComponentStateSerialization
>    * @see #checkComponentTreeStateSerialization
>    */
>   public static boolean checkSessionSerialization(ExternalContext extContext)

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