The External Cache Invalidator Class implements a new modality for Cocoon2's cache System. It provides a new way to invalidate cached pages stored into Cocoon cache system with a simple external message interpreted by an XSP page. It mean that you could generate a dynamic page with DBPrism or with an XSP page and stored it into the Cocoon Cache system, this page will remaind valid into the cache until an XML message says to this server implementation that the stored page is no longer valid, when a new request come to Cocoon it will generate a new one. This kind of synchronization is commonly implemented through triggers into the database that provides the information for the dynamic page.

• public boolean isRegistered( ESIKey key) , Returns true or false if the key argument is registered as a Cached Page.
• public long getCacheablePageKey(ESIKey key), Returns a long value used by Cocoon's cache system to locate a Cached Page.
• public void registerCacheablePage(ESIKey key), Registers a Cached Page, this page is identified by an ESIKey object which holds the URL for this page, his encoded argument and the long value used by Cocoon's cache system to identified the cached page.
• public int removeCacheablePage(String username, String password, String URI, String URIRegExp, ESIKey key, int ttl), Removes a previous cached page identified by the URI path, the URIRegExp regular expresion and the encoded arguments, it requires a valid username and password to access to the cache server. This method do not remove automatically the page, it stores the ESIKey into a queue of pages to invalidate, this queue is cheked every 1 second by default. See DatabaseServerImpl section for more details. ttl (or time-to-live) value is reserved for future use. URI is a base path for the page(s) to be remove. URIRegExp is a regular expresion used for matching with the page(s) to remove

Note about URI and URIRegExp:

URI       = /p1/p2/p3/ and
URIRegExp = ^/p1/p2/p3/file.htm$ or
URI       = / and
URIRegExp = ^/p1/p2/p3/file.htm$
match with the same page 
        
          
        
          
        
          
        
          
        
          
        
          /p1/p2/p3/file.htm.
Since the regular expression is done against the set of page objects containing
the common URIPREFIX path prefix, it is obvious that the smaller the set,
the more efficient the invalidation.
        
      
        
      
        
      
        
      
        
      
        
      
        

• ROLE, Defines Avalon Role for this server.
• NONE, EXTERNAL, NOP, Used by DBPrismGenerator to identified three kind of cacheability rules. None means that the page is no cacheable, External means that the page is controled by the External Cache Invalidator Server and the method generateValidity() will return an instance of ExternalCacheValidity object, NOP means that the page is cacheable and will remains in the Cocoon cache during the life of Cocoon instance (generateValidity() will return an object of type NOPCacheValidity).
• COPY_ARG_NAME, Used by the CocoonRequestWrapper to merge the standard servlet http request arguments with the sitemap arguments.
• COPY_NO and COPY_YES, Special values used into Copy-Request-Arguments, false mean that only pass DBPrismGenerator sitemap parameters, true mean that all the http arguments and cookies are passed to the DBPrismGenerator.
• CACHE_CONTROL_ARG_NAME, Its the name on the sitemap argument that defines the cacheability behaviour on DBPrismGenerator.
• CACHE_CONTROL_EXTERNAL, CACHE_CONTROL_NOP, CACHE_CONTROL_NONE, Values defined for the previous one argument on the sitemap syntax.

This selector shows how to invalidate an XSP page which includes the necesary code to register this page as External Invalidated.

POST /dbprism/x-dbprism-cache-invalidate HTTP/1.0
Authorization: BASIC aW52YWxpZGF0b3I6aW52YWxpZGF0b3I=
Content-Length: 213

<?xml version="1.0"?>
<INVALIDATION VERSION="WCS-1.0">
  <OBJECT>
    <BASICSELECTOR URI="/ext/xsp/simple_ext"/>
    <INFO VALUE="simple_ext.xsp"/>
    <ACTION REMOVALTTL="0"/>
  </OBJECT>
</INVALIDATION>

POST /dbprism/x-dbprism-cache-invalidate HTTP/1.0
Authorization: BASIC aW52YWxpZGF0b3I6aW52YWxpZGF0b3I=
Content-Length: 450

<?xml version="1.0"?>
<INVALIDATION VERSION="WCS-1.0">
  <OBJECT>
    <ADVANCEDSELECTOR URIPREFIX="/ext/xsp/" URIEXP="simple_ext">
      <OTHER TYPE="sitemap" NAME="test_param1" VALUE="test1"/>
      <OTHER TYPE="sitemap" NAME="test_param2" VALUE="test2"/>
      <OTHER TYPE="http" NAME="id_user" VALUE="user1"/>
    </ADVANCEDSELECTOR>
    <INFO VALUE="simple_ext.xsp?id_user=1"/>
    <ACTION REMOVALTTL="0"/>
  </OBJECT>
</INVALIDATION>

The above example will invalidate the XSP page /ext/xsp/simple_ext located under the path /ext/xsp/, only if the sitemap and http parameters match with the values provided, in this example, if the personalized attribute was id_user, pages with id_user not equal to user1 will remains valid into the cache system.

POST /dbprism/x-dbprism-cache-invalidate HTTP/1.0
Authorization: BASIC aW52YWxpZGF0b3I6aW52YWxpZGF0b3I=
Content-Length: 392

<?xml version="1.0"?>
<INVALIDATION VERSION="WCS-1.0">
  <OBJECT>
    <ADVANCEDSELECTOR URIPREFIX="/ext/xsp/" URIEXP="simple.*">
      <OTHER TYPE="sitemap" NAME="test_param1" VALUE="test1"/>
      <OTHER TYPE="sitemap" NAME="test_param2" VALUE="test2"/>
    </ADVANCEDSELECTOR>
    <INFO VALUE="all_simple_under_ext_xsp"/>
    <ACTION REMOVALTTL="0"/>
  </OBJECT>
</INVALIDATION>

The above example will invalidate the content of the XSP pages that match with the regular expresion simple.* and located under the path /ext/xsp/, it means that, indepent of the personalized attribute (id_user) the pages that match with the sitemap parameters (test_param1 and test_param2) and regular expresion will be removed from the cache..