com.github.wuic.servlet

Class HtmlParserFilter

java.lang.Object

com.github.wuic.util.PollingScheduler<ContextBuilderConfigurator>

com.github.wuic.context.ContextBuilderConfigurator

com.github.wuic.servlet.HtmlParserFilter

All Implemented Interfaces:

Runnable, Filter

public class HtmlParserFilter
extends ContextBuilderConfigurator
implements Filter

This filter uses the WuicFacade to configure the related ContextBuilder with workflow built on the fly when an HTML page is filtered. The created workflow uses default engines.

This filters uses an internal NutDao to retrieve referenced nuts when parsing HTML. By default, the DAO built from a RequestDispatcherNutDao. DAO is configured like this for consistency reason because the version number must be computed from content when scripts are declared inside tag. User can takes control over NutDao creation by extending this class and overriding the createContextNutDaoBuilder(String, com.github.wuic.context.ContextBuilder, String) method.

WUIC considers that a filtered content is static by default and could be cached as any other resource. This will be the cache for many applications that does not use server-side HTML generation. However, if the content is dynamic, e.g it is not the same for two different users, WUIC should not cache it to serve an up-to-date response body. The filter detects a dynamic content when it has been generated with a tag officially provided by WUIC (like taglib for JSP or processor for Thymeleaf). In case of a dynamic content generated otherwise, you can use the init-param FORCE_DYNAMIC_CONTENT to tell WUIC to consider the content always dynamic.

This filter supports server-hint mode. Server-hint is enabled by default. It associates to all resources that should be loaded as soon as possible by the HTML page a "Link" header with "preload" rel value. Other resources are associated to a "prefetch" rel value to tell the browser to download them with a low priority. Note that proxy like "nghttpx" can use this header to push the resource over HTTP/2.

Server-push is also supported. It relies on a PushService implementation discovered in the classpath. It will be enabled by default if an implementation is found by the ServiceLoader. You can disable the server-push with the DISABLE_SERVER_PUSH init-param.

Since:

0.4.4

Version:

1.0

Author:

Guillaume DROUET

Nested Class Summary

Nested classes/interfaces inherited from class com.github.wuic.util.PollingScheduler

PollingScheduler.Polling

Field Summary

Fields

Modifier and Type	Field and Description
static String	DISABLE_SERVER_PUSH Property that tells the filter to use or not HTTP2 server push.
static String	FORCE_DYNAMIC_CONTENT An init parameter that tells the filter how to consider the filtered content dynamic or not.
static String	SKIP_FILTER If an attribute with this name is defined in the filtered request, then this filter will skip its related operation.

Constructor Summary

Constructors

Constructor and Description
HtmlParserFilter() Builds a new instance.
HtmlParserFilter(WuicFacade wuicFacade) Builds a new instance with a specific WuicFacade and the default RequestDispatcherNutDao builder as root NutDao builder.
HtmlParserFilter(WuicFacade wuicFacade, String rootNuDaoBuilderId) Builds a new instance with a specific WuicFacade and a root NutDao builder.

Method Summary

Methods

Modifier and Type	Method and Description
protected ByteArrayNut	configureBuilder(HttpServletRequest request, String path, ContextBuilder contextBuilder, String workflowId, byte[] content) Configures the workflow corresponding to the given ID in the specified context builder.
protected ContextBuilder.ContextNutDaoBuilder	createContextNutDaoBuilder(String id, ContextBuilder contextBuilder, String rootNutDaoBuilderId) Creates a new ContextBuilder.ContextNutDaoBuilder with the given ContextBuilder.
void	destroy()
void	doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
protected Long	getLastUpdateTimestampFor(String path) Retrieves a timestamp that indicates the last time this nut has changed.
ProcessContext	getProcessContext() Gets the process context associated to the tag while configuring.
String	getTag() Gets the tag to use to identify the set of settings defined when ContextBuilderConfigurator.configure(ContextBuilder) is called.
void	init(FilterConfig filterConfig)
int	internalConfigure(ContextBuilder ctxBuilder) Configures the given context internally.

Methods inherited from class com.github.wuic.context.ContextBuilderConfigurator

configure, run, setMultipleConfigurations

Methods inherited from class com.github.wuic.util.PollingScheduler

getNutObservers, getPollingInterval, observe, setPollingInterval

Methods inherited from class java.lang.Object

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

Field Detail

DISABLE_SERVER_PUSH

public static final String DISABLE_SERVER_PUSH

Property that tells the filter to use or not HTTP2 server push. Server push is enabled by default.

See Also:

Constant Field Values

FORCE_DYNAMIC_CONTENT

public static final String FORCE_DYNAMIC_CONTENT

An init parameter that tells the filter how to consider the filtered content dynamic or not.

See Also:

Constant Field Values

SKIP_FILTER

public static final String SKIP_FILTER

If an attribute with this name is defined in the filtered request, then this filter will skip its related operation.

Constructor Detail

HtmlParserFilter

public HtmlParserFilter(WuicFacade wuicFacade,
                String rootNuDaoBuilderId)

Builds a new instance with a specific WuicFacade and a root NutDao builder.

Parameters:

wuicFacade - the WUIC facade

rootNuDaoBuilderId - the root nut DAO builder ID

HtmlParserFilter

public HtmlParserFilter(WuicFacade wuicFacade)

Builds a new instance with a specific WuicFacade and the default RequestDispatcherNutDao builder as root NutDao builder.

Parameters:

wuicFacade - the WUIC facade

HtmlParserFilter

public HtmlParserFilter()

Builds a new instance. The internal WuicFacade will be initialized when init(javax.servlet.FilterConfig) method will be invoked. At this moment, this class will get the object from WuicServletContextListener. In this case, the listener must be declared in th servlet container configuration.

Method Detail

init

public void init(FilterConfig filterConfig)
          throws ServletException

Specified by:

init in interface Filter

Throws:

ServletException

createContextNutDaoBuilder

protected ContextBuilder.ContextNutDaoBuilder createContextNutDaoBuilder(String id,
                                                             ContextBuilder contextBuilder,
                                                             String rootNutDaoBuilderId)

Creates a new ContextBuilder.ContextNutDaoBuilder with the given ContextBuilder.

Parameters:

id - the ID

contextBuilder - the context builder to use

rootNutDaoBuilderId - the root NutDao builder which should be extended by the new builder

Returns:

the nut DAO

doFilter

public void doFilter(ServletRequest request,
            ServletResponse response,
            FilterChain chain)
              throws IOException,
                     ServletException

Specified by:

doFilter in interface Filter

Throws:

IOException

ServletException

configureBuilder

protected ByteArrayNut configureBuilder(HttpServletRequest request,
                            String path,
                            ContextBuilder contextBuilder,
                            String workflowId,
                            byte[] content)
                                 throws IOException,
                                        WuicException

Configures the workflow corresponding to the given ID in the specified context builder.

Parameters:

request - the request

path - the filtered nut path

contextBuilder - the builder

workflowId - the workflow ID

Returns:

the created nut

Throws:

WuicException - if context can't be refreshed

IOException - if any I/O error occurs

destroy

public void destroy()

Specified by:

destroy in interface Filter

internalConfigure

public int internalConfigure(ContextBuilder ctxBuilder)

Configures the given context internally. This method is called just after the ContextBuilder has been tagged with the value returned by ContextBuilderConfigurator.getTag() method. Once the execution of this method is terminated, the tag is released.

To activate polling on this configurator, this method should returns a positive integer representing the polling interval in seconds.

Specified by:

internalConfigure in class ContextBuilderConfigurator

Parameters:

ctxBuilder - the builder

getTag

public String getTag()

Gets the tag to use to identify the set of settings defined when ContextBuilderConfigurator.configure(ContextBuilder) is called.

Specified by:

getTag in class ContextBuilderConfigurator

Returns:

the tag

getLastUpdateTimestampFor

protected Long getLastUpdateTimestampFor(String path)
                                  throws IOException

Retrieves a timestamp that indicates the last time this nut has changed.

Specified by:

getLastUpdateTimestampFor in class PollingScheduler<ContextBuilderConfigurator>

Parameters:

path - the real path of the nut

Returns:

the timestamp

Throws:

IOException - if any I/O error occurs

getProcessContext

public ProcessContext getProcessContext()

Gets the process context associated to the tag while configuring.

Specified by:

getProcessContext in class ContextBuilderConfigurator

Returns:

the process context