Request Component

The X:Forge Request Component provides an easy way to retrieve one or more parameters from the Request. This fundamental feature lets users build dynamic XML content based on multiple request parameters: a step beyond traditional static content publishing suitable for merging sources dynamically.

Configuration

Declaration

The use of this tool needs a declaration in the X:Forge configuration file. All this is simply achieved through the association of an alias for org.bibop.xml.xforge.components.http.XForgeServletRequestComponent. The Request component definition can be refined declaring or not a boolean parameter called 'allowemptyparameters' which has a default true value to allow or deny this kind of requests. 


<component-instance name="Request" 
	class="org.bibop.xml.xforge.components.http.ServletRequestComponent"
	allowemptyparameters="false"
	logger="mylogger"/>

Usage

Invocation

Once declared and configured the component can be used straight away in XML documents by invoking it through an <xf:process> tag and passing to it a "Request" parameter that contains the chosen names for params. Let's have an example: 


<level>
  <xf:process using="Request">
    <xf:parameter name="level">1</xforge:parameter>
  </xf:process>
</level>

Resulting XML

This code generates one parameter named 'level' whose value is set by the component defined in the X:Forge configuration file through the alias 'Request' namely org.bibop.xml.xforge.components.http.ServletRequestComponent. The resulting bit of XML shown in its simplicity is.... 


<level>1</level>

Simple but dynamic: the same XML file will include a different level depending on the parameter requested!

Errors

Known Error Conditions

  • No parameter defined in the XML is passed in the Request.
  • An empty parameter is passed after having configured the 'allowemptyparameters' option as 'false' in the X:Forge configuration file.

Error Handling

All exceptions are thrown back to the caller. Here is an example: 


org.xml.sax.SAXException: No value / default value has been specified for request parameter level
	at org.bibop.xml.xforge.components.http.ServletRequestComponent
			.toSax(ServletRequestComponent.java:67)
	at org.bibop.xml.xforge.XForgeProcessElement.toSax(XForgeProcessElement.java:132)
	at org.bibop.xml.xforge.XForgeProcessor.endElement(XForgeProcessor.java:294)
	at org.apache.cocoon.xml.dom.DOMStreamer.setElement(DOMStreamer.java:204)
	at org.apache.cocoon.xml.dom.DOMStreamer.processNode(DOMStreamer.java:107)
	at org.apache.cocoon.xml.dom.DOMStreamer.processChildren(DOMStreamer.java:148)
	at org.apache.cocoon.xml.dom.DOMStreamer.setElement(DOMStreamer.java:203)
	at org.apache.cocoon.xml.dom.DOMStreamer.processNode(DOMStreamer.java:107)
	at org.apache.cocoon.xml.dom.DOMStreamer.processChildren(DOMStreamer.java:148)
	at org.apache.cocoon.xml.dom.DOMStreamer.setElement(DOMStreamer.java:203)
	at org.apache.cocoon.xml.dom.DOMStreamer.processNode(DOMStreamer.java:107)
	at org.apache.cocoon.xml.dom.DOMStreamer.processChildren(DOMStreamer.java:148)
	at org.apache.cocoon.xml.dom.DOMStreamer.setElement(DOMStreamer.java:203)
	at org.apache.cocoon.xml.dom.DOMStreamer.processNode(DOMStreamer.java:107)
	at org.apache.cocoon.xml.dom.DOMStreamer.processChildren(DOMStreamer.java:148)
	at org.apache.cocoon.xml.dom.DOMStreamer.setDocument(DOMStreamer.java:155)
	at org.apache.cocoon.xml.dom.DOMStreamer.processNode(DOMStreamer.java:101)
	at org.apache.cocoon.xml.dom.DOMStreamer.stream(DOMStreamer.java:87)
	at org.bibop.xml.xforge.XForgeProcessor.process(XForgeProcessor.java:145)
	at org.bibop.xml.xforge.helpers.XForgeC1Processor.process(XForgeC1Processor.java:90)
	at org.apache.cocoon.Engine.handle(Engine.java:359)
	at org.apache.cocoon.Cocoon.service(Cocoon.java:181)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
	at org.apache.tomcat.core.ServletWrapper.doService(ServletWrapper.java:404)
	at org.apache.tomcat.core.Handler.service(Handler.java:286)
	at org.apache.tomcat.core.ServletWrapper.service(ServletWrapper.java:372)
	at org.apache.tomcat.core.ContextManager.internalService(ContextManager.java:797)
	at org.apache.tomcat.core.ContextManager.service(ContextManager.java:743)
	at org.apache.tomcat.service.connector.Ajp12ConnectionHandler
			.processConnection(Ajp12ConnectionHandler.java:166)
	at org.apache.tomcat.service.TcpWorkerThread.runIt(PoolTcpEndpoint.java:416)
	at org.apache.tomcat.util.ThreadPool$ControlRunnable.run(ThreadPool.java:498)
	at java.lang.Thread.run(Thread.java:484)