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Classes:
Keyword

Class TCachePageStatePersister

TComponent
   |
   --TCachePageStatePersister

TCachePageStatePersister class

TCachePageStatePersister implements a page state persistent method based on cache. Page state are stored in cache (e.g. memcache, DB cache, etc.), and only a small token is passed to the client side to identify the state. This greatly reduces the size of the page state that needs to be transmitted between the server and the client. Of course, this is at the cost of using server side resource.

A cache module has to be loaded in order to use TCachePageStatePersister. By default, TCachePageStatePersister will use the primary cache module. A non-primary cache module can be used by setting CacheModuleID. Any cache module, as long as it implements the interface ICache, may be used. For example, one can use TDbCache, TMemCache, TAPCCache, etc.

TCachePageStatePersister uses CacheTimeout to limit the data that stores in cache.

Since server resource is often limited, be cautious if you plan to use TCachePageStatePersister for high-traffic Web pages. You may consider using a small CacheTimeout.

There are a couple of ways to use TCachePageStatePersister. One can override the page's TPage::getStatePersister() method and create a TCachePageStatePersister instance there. Or one can configure the pages to use TCachePageStatePersister in page configurations as follows,

  1. <pages StatePersisterClass="System.Web.UI.TCachePageStatePersister"
  2. StatePersister.CacheModuleID="mycache"
  3. StatePersister.CacheTimeout="3600" />
Note in the above, we use StatePersister.CacheModuleID to configure the cache module ID for the TCachePageStatePersister instance.

The above configuration will affect the pages under the directory containing this configuration and all its subdirectories. To configure individual pages to use TCachePageStatePersister, use

  1. <pages>
  2. <page id="PageID" StatePersisterClass="System.Web.UI.TCachePageStatePersister" />
  3. </pages>

Since: 3.1.1
Author: Qiang Xue <qiang.xue@gmail.com>

Method Summary
protected  string
calculateKey ( string $timestamp)
ICache
string
integer
string
void
getPage ( TPage 0)
mixed
load ()
Loads page state from cache.
void
save ( mixed $state)
Saves state in cache.
void
setCacheModuleID ( string $value)
void
setCacheTimeout ( integer $value)
void
setKeyPrefix ( string $value)
void
setPage ( TPage $page)
Methods Inherited From TComponent
TComponent::addParsedObject(), TComponent::attachEventHandler(), TComponent::canGetProperty(), TComponent::canSetProperty(), TComponent::createdOnTemplate(), TComponent::detachEventHandler(), TComponent::evaluateExpression(), TComponent::evaluateStatements(), TComponent::getEventHandlers(), TComponent::getSubProperty(), TComponent::hasEvent(), TComponent::hasEventHandler(), TComponent::hasProperty(), TComponent::raiseEvent(), TComponent::setSubProperty(), TComponent::__get(), TComponent::__set()

Method Details

calculateKey

protected string calculateKey (string $timestamp )

Input
string$timestampmicro timestamp when saving state occurs
Output
string a key that is unique per user request
Exception

getCache

public ICache getCache ()

Output
ICache the cache module being used for data storage
Exception

getCacheModuleID

public string getCacheModuleID ()

Output
string the ID of the cache module.
Exception

getCacheTimeout

public integer getCacheTimeout ()

Output
integer the number of seconds in which the cached state will expire. Defaults to 1800.
Exception

getKeyPrefix

public string getKeyPrefix ()

Output
string prefix of cache variable name to avoid conflict with other cache data. Defaults to 'statepersister'.
Exception

getPage

public void getPage (TPage 0 )

Input
TPage0the page that this persister works for
Output
Exception

load

public mixed load ()

Loads page state from cache.

Output
mixed the restored state
Exception
throwsTHttpException if page state is corrupted

save

public void save (mixed $state )

Saves state in cache.

Input
mixed$statestate to be stored
Output
Exception

setCacheModuleID

public void setCacheModuleID (string $value )

Input
string$valuethe ID of the cache module. If not set, the primary cache module will be used.
Output
Exception

setCacheTimeout

public void setCacheTimeout (integer $value )

Input
integer$valuethe number of seconds in which the cached state will expire. 0 means never expire.
Output
Exception
throwsTInvalidDataValueException if the number is smaller than 0.

setKeyPrefix

public void setKeyPrefix (string $value )

Input
string$valueprefix of cache variable name to avoid conflict with other cache data
Output
Exception

setPage

public void setPage (TPage $page )

Input
TPage$pagethe page that this persister works for.
Output
Exception