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http://nagoya.apache.org/bugzilla/show_bug.cgi?id=6879 [patch] Cache improvement using ESI invalidation protocol Summary: [patch] Cache improvement using ESI invalidation protocol Product: Cocoon 2 Version: 2.0.1 Platform: All URL: http://www.dbprism.com.ar/dbprism/doc/xdocs/Server.html OS/Version: All Status: NEW Severity: Normal Priority: Other Component: general components AssignedTo: [EMAIL PROTECTED] ReportedBy: [EMAIL PROTECTED] Hi all: I have implemented and External Cache Invalidator object and server to implement a synchorized way for invalidating Cocoon2's cached pages (from outside) through an simple XSP page that interpret an HTTP post message. This solution is implemented by DB Prism Generator for Cocoon2 and is usefull for making (using content agregation) news feeds "a la" My yahoo, this kind of news feed are implemented selecting the news from a simple table inside the database, this news are only invalidated when the database process an update/insert or delete on the corrected table that fires a trigger which send an http messages to the invalidator XSP page, this message (http://www.w3.org/TR/esi-invp) includes information about the url arguments and cookies used to indentified the page. When this message is processed by the invalidator XSP page contact the invalidator server and enqueue the message. Cocoon will ask to the ExternalCacheValidity which implements the interface CacheValidity for the validity of the page, this object contact the invalidator server and return true or false depending on the response of the External invalidator server. Here the class which implement the previous functionality: - org.apache.cocoon.components.cache.Server (Interface which is an Avalon component and defines the functionality of External Invalidator Servers) - org.apache.cocoon.components.cache.InMemoryServerImpl (Concrete Class which implements the previous one interface and provide an InMemory implementation of the Invalidator container, this class uses a HashMap for storing cached pages keys and a linked list for implementing the queue of invalidation messages) - org.apache.cocoon.caching.ExternalCacheValidity ( implements org.apache.cocoon.caching.CacheValidity and return true or false if the pages is cached by the external invalidator server. Note: Cached by the external invalidator server means that this page is not stored by the server, the pages is stored in the Cocoon cache system, this server only register an encoded url which identified the page and return true or false if the page is valid. - An XSP page invalidte.xsp, which receives http post messages whith the pages to be removed from the server. Usabilty, DBPrismGenerator uses this technique interpreting an internal sitemap argument named Cache-Control, here an example of this setting: <map:match pattern="header/**.xml"> <map:generate type="dbprism" src="/cms/CMSj.header"> <map:parameter name="Cache-Control" value="External"/> <map:parameter name="source" value="/{1}.xml"/> <map:parameter name="printable" value="no"/> </map:generate> <map:serialize/> </map:match> This means that the resource will be resolved by DBPrismGenerator (type=dbprism) and this generator returns on the method generateValidity() an object of type ExternalCacheValidity, here the code: .... } else if (this.cacheControl==Server.EXTERNAL) { if (getLogger().isDebugEnabled()) getLogger().debug("generateValidity called returning ExternalCacheValidity"); return new ExternalCacheValidity(this.generateKey(),this.cacheServer,this.encodedURL); .... This external cache validity objects is identified by a unique key (generated by the CacheServer) and the encoded url, the encoded url is generated with the syntax /path/object?arg1=val1&arg2=val&Coookie:name1=val1&Cookie:name2=val2, this url is used then to ask for the availibilty of the page on the server or not. DBPrismGenerator uses this object but, its possible to use into an XSP page too, see simple_ext.xsp as an example of an XSP page which is externally invalidated. Here an example of the invalidation message sent by the database to Cocoon to invalidate an specific page: POST /cocoon/x-dbprism-cache-invalidate HTTP/1.0 Authorization: BASIC aW52YWxpZGF0b3I6aW52YWxpZGF0b3I= Content-Length: 189 <?xml version="1.0"?> <INVALIDATION VERSION="WCS-1.0"> <OBJECT> <BASICSELECTOR URI="docs/samples/xsp/simple_ext.xsp"/> <ACTION REMOVALTTL="0"/> </OBJECT> </INVALIDATION> Obviusly the External Cache Invalidator server use an username and password to validate the request which arrive from outside Cocoon, this user/password is encoded into http header Authorization in Base 64 form (in this case invalidator/invalidator), this invalidation xml message means that the XSP will invalidate the XSP demo page (docs/samples/xsp/simple_ext.xsp) with no arguments. REMOVALTTL=seconds is reserved for future use on the Cache Server if it imlement and prioritized list of invalidation messages, this mean that messages with different time-to-live will re-order in the invalidation queue. Here an example of an Oracle trigger which sends an invalidation message to Cocoon when a user update a CMS page : CREATE OR REPLACE TRIGGER TOPIC_INVALID_TRIG AFTER UPDATE on FAQ_TOPICS DECLARE par cache.cache_parameters; BEGIN par.num_vals := 1; par.names(1) := 'ext'; par.vals(1) := 'html'; cache.invalidate('webcachehost',8888,'/cms/','faq.doIt',par); END; It uses an stored procedure cache.invalidate which compose the xml post message showed above. I attached the sources of the class and examples for more information. Best regards, Marcelo. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, email: [EMAIL PROTECTED]
