org.apache.cocoon.generation
Class EventCacheGenerator

java.lang.Object
  org.apache.avalon.framework.logger.AbstractLogEnabled
      org.apache.cocoon.xml.AbstractXMLProducer
          org.apache.cocoon.generation.AbstractGenerator
              org.apache.cocoon.generation.ServiceableGenerator
                  org.apache.cocoon.generation.EventCacheGenerator

All Implemented Interfaces:

CacheableProcessingComponent, Configurable, Disposable, Generator, LogEnabled, Poolable, Recyclable, Serviceable, SitemapModelComponent, XMLProducer

public class EventCacheGenerator

extends ServiceableGenerator

implements Configurable, CacheableProcessingComponent

Generator wrapper that forwards generation to to its delegate but overides its caching strategy by replacing it with an event-cache aware implementation.

Sitemap configuration is as follows:
<map:generator name="event-cache" src="org.apache.cocoon.generation.EventCacheGenerator" >
<factory name="my-event" value="com.my.EventFactoryImpl" />
<factory name="my-other-event" value="com.myother.EventFactoryImpl" />
</map:generator>

Two event types are preconfigured: NamedEvent (name="named") and NameValueEvent (name="name-value").

Pipeline usage is as follows:
<map:generate type="event-cache" src="delegate-src">
<map:parameter name="delegate" value="delegate-type" />
<map:parameter name="event-type" value="my-event" />
<!-- my event parameters -->
<map:parameter name="event-name" value="some name" />
<map:parameter name="event-value" value="some value" />
</map:generate>

The two preconfigured event types take the following parameters:
- event-type 'named': parameter 'event-name'
- event-type 'name-value': parameter 'event-name' and parameter 'event-value'

The src attribute and all parameters are passed as is to delegate generator.

TODO: share common code with EventCacheTransformer

Author:

Unico Hommes

Field Summary

static String	DELEGATE_PARAM
static String	EVENT_TYPE_DEFAULT
static String	EVENT_TYPE_PARAM
static String	FACTORY_CONF
static String	FACTORY_NAME_CONF
static String	FACTORY_NAME_TYPE
static String	NAME_VALUE_EVENT_TYPE
static String	NAMED_EVENT_TYPE

Fields inherited from class org.apache.cocoon.generation.ServiceableGenerator

manager

Fields inherited from class org.apache.cocoon.generation.AbstractGenerator

objectModel, parameters, resolver, source

Fields inherited from class org.apache.cocoon.xml.AbstractXMLProducer

contentHandler, EMPTY_CONTENT_HANDLER, lexicalHandler, xmlConsumer

Fields inherited from interface org.apache.cocoon.generation.Generator

ROLE

Constructor Summary

EventCacheGenerator()

Method Summary

void	configure(Configuration configuration)
void	dispose() Release all resources.
void	generate() Generate the XML and stream it into the pipeline
Serializable	getKey() Generate the unique key for the resource being rendered.
SourceValidity	getValidity() Generate the validity object.
void	recycle() Recycle the generator by removing references
void	service(ServiceManager manager) Set the current ServiceManager instance used by this Serviceable.
void	setConsumer(XMLConsumer consumer) Set the XMLConsumer that will receive XML data.
void	setup(SourceResolver resolver, Map objectModel, String src, Parameters par) Set the SourceResolver, object model Map, the source and sitemap Parameters used to process the request.

Methods inherited from class org.apache.cocoon.xml.AbstractXMLProducer

setContentHandler, setLexicalHandler

Methods inherited from class org.apache.avalon.framework.logger.AbstractLogEnabled

enableLogging, getLogger, setupLogger, setupLogger, setupLogger

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

NAME_VALUE_EVENT_TYPE

public static final String NAME_VALUE_EVENT_TYPE

See Also:

Constant Field Values

EVENT_TYPE_DEFAULT

public static final String EVENT_TYPE_DEFAULT

See Also:

Constant Field Values

NAMED_EVENT_TYPE

public static final String NAMED_EVENT_TYPE

See Also:

Constant Field Values

FACTORY_CONF

public static final String FACTORY_CONF

See Also:

Constant Field Values

FACTORY_NAME_CONF

public static final String FACTORY_NAME_CONF

See Also:

Constant Field Values

FACTORY_NAME_TYPE

public static final String FACTORY_NAME_TYPE

See Also:

Constant Field Values

DELEGATE_PARAM

public static final String DELEGATE_PARAM

See Also:

Constant Field Values

EVENT_TYPE_PARAM

public static final String EVENT_TYPE_PARAM

See Also:

Constant Field Values

Constructor Detail

EventCacheGenerator

public EventCacheGenerator()

Method Detail

service

public void service(ServiceManager manager)
             throws ServiceException

Description copied from class: ServiceableGenerator

Set the current ServiceManager instance used by this Serviceable.

Specified by:

service in interface Serviceable

Overrides:

service in class ServiceableGenerator

Throws:

ServiceException

configure

public void configure(Configuration configuration)
               throws ConfigurationException

Specified by:

configure in interface Configurable

Throws:

ConfigurationException

setup

public void setup(SourceResolver resolver,
                  Map objectModel,
                  String src,
                  Parameters par)
           throws ProcessingException,
                  SAXException,
                  IOException

Description copied from class: AbstractGenerator

Set the SourceResolver, object model Map, the source and sitemap Parameters used to process the request.

Specified by:

setup in interface SitemapModelComponent

Overrides:

setup in class AbstractGenerator

Throws:

ProcessingException

SAXException

IOException

setConsumer

public void setConsumer(XMLConsumer consumer)

Description copied from interface: XMLProducer

Set the XMLConsumer that will receive XML data.

Specified by:

setConsumer in interface XMLProducer

Overrides:

setConsumer in class AbstractXMLProducer

generate

public void generate()
              throws IOException,
                     SAXException,
                     ProcessingException

Description copied from interface: Generator

Generate the XML and stream it into the pipeline

Specified by:

generate in interface Generator

Throws:

IOException

SAXException

ProcessingException

recycle

public void recycle()

Description copied from class: AbstractGenerator

Recycle the generator by removing references

Specified by:

recycle in interface Recyclable

Overrides:

recycle in class AbstractGenerator

getKey

public Serializable getKey()

Description copied from interface: CacheableProcessingComponent

Generate the unique key for the resource being rendered.

The cache key is the single most important part of the caching implementation. If you don't get it right, you can introduce more load on the caching engine than is necessary. It is important that the cache key has the following attributes:

• It must be Serializable (part of the contract of this method).
• It must be Immutable--the key is used as a lookup value.
• It must be Unique within the space of the component (i.e. the key "1" for MyCacheableComponent must be for the same resource every time, but we don't have to worry about the key "1" for YourCacheableComponent).
• The equals() and hashCode() methods must be consistent (i.e. if two keys are equal, the hashCode must also be equal).

Thankfully there is a perfectly suitable object that satisfies these obligations from Java's core: java.lang.String. You can also use your own specific key objects provided they respect the above contracts.

Important:If the cache key is null then your component will not be cached at all. You can use this to your advantage to cache some things but not others.

Specified by:

getKey in interface CacheableProcessingComponent

Returns:

The generated key or null if the component is currently not cacheable.

getValidity

public SourceValidity getValidity()

Description copied from interface: CacheableProcessingComponent

Generate the validity object. This method is invoked after the getKey() method.

The caching contracts use the Excalibur SourceValidity interface to determine whether a resource is valid or not. The validity can be a compound check that incorporates time since creation, parameter values, etc. As long as the sitemap can determine whether the cached resource is valid or not. More information is available on the Apache Excalibur site. Alternatively you can use the built in CacheValidity objects in the org.apache.cocoon.caching package and then use the CacheValidityToSourceValidity adaptor object.

Specified by:

getValidity in interface CacheableProcessingComponent

Returns:

The generated validity object or null if the component is currently not cacheable.

dispose

public void dispose()

Description copied from class: ServiceableGenerator

Release all resources.

Specified by:

dispose in interface Disposable

Overrides:

dispose in class ServiceableGenerator