org.apache.commons.pipeline.config
Class PipelineRuleSet

java.lang.Object
  org.apache.commons.digester.RuleSetBase
      org.apache.commons.pipeline.config.PipelineRuleSet

All Implemented Interfaces:

org.apache.commons.digester.RuleSet

public class PipelineRuleSet
extends org.apache.commons.digester.RuleSetBase

This is a Digester RuleSet that provides rules for parsing a pipeline XML file. The rules defined by this object are used for parsing the following tags:

• <pipeline></pipeline>
  The root element of the XML configuration file for a pipeline. This tag supports two optional attributes that are for use only when configuring branch pipelines, key and configURI. These attributes are described more fully below in the <branch> documentation.
• <driverFactory className="MyDriverFactory" id="my_id" ... />
  This tag is used to create and configure a StageDriverFactory that will be used to create StageDriver instances for stages in the parent pipeline. Each StageDriverFactory is identified by a unique string identifier that is used by the <stage> tag to identify the factory used to create the driver for the stage. The class of the factory (which must supply a no-argument constructor) is specified by the className attribute, and all other additional attributes are used by Digester to configure the associated properties (using standard Java bean naming conventions) of the driver instance created.
• <stage className="MyStageClass" driverFactoryId="name" ... ></stage>
  A single stage is created, configured, and added to the parent pipeline using this tag. Stages created in this manner are added to the pipeline in the order that they occur in the configuration file. The class of the stage (which must provide a no-argument constructor) is specified by the className attribute. Each stage should be associated with a previously declared driver factory by use of the driverFactoryId attribute. All other attributes are used by Digester to set bean properties on the newly created Stage object.
• <feed/>
  Enqueue an object onto the first stage in the pipeline. Note that this must come after the first stage declaration in the configuration file, otherwise the queue for the first stage does not exist yet and the fed values will be discarded.

  There are two types of usage available, provided by the following subtags:

  • <value>my_value</value>
    Feed the string value of the body of this tag to the first stage in the pipeline.
  • <object className="MyClass" ... />
    This tag uses the standard Digester ObjectCreateRule to create an arbitrary object of the specified class (which must provide a no-argument constructor) to the first stage in the pipeline. All attributes other than className are used by Digester to set bean properties on the newly created object.
• <branch/>
  Add a branch to a pipeline. The contents of this tag should be one or more <pipeline/> declarations. Branch pipelines added in this fashion must be configured with an attribute named key that holds the name by which the branch pipeline will be referred to.

  Branch pipelines may be configured either inline in the main configuration file or in a separate file referred to by the configURI pipeline attribute.

Field Summary

Fields inherited from class org.apache.commons.digester.RuleSetBase

namespaceURI

Constructor Summary

PipelineRuleSet()
Creates a new instance of the rule set used by Digester to configure a pipeline.

PipelineRuleSet(List<org.apache.commons.digester.RuleSet> nestedRuleSets)
Creates a new pipeline rule set with the specified collection of additional rule sets that may be used for recursive creation of branch pipelines.

Method Summary

void	addRuleInstances(org.apache.commons.digester.Digester digester) Adds the rule instances for pipeline, stage, and enqueue tasks to the Digester instance supplied.

Methods inherited from class org.apache.commons.digester.RuleSetBase

getNamespaceURI

Methods inherited from class java.lang.Object

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

Constructor Detail

PipelineRuleSet

public PipelineRuleSet()

Creates a new instance of the rule set used by Digester to configure a pipeline.

PipelineRuleSet

public PipelineRuleSet(List<org.apache.commons.digester.RuleSet> nestedRuleSets)

Creates a new pipeline rule set with the specified collection of additional rule sets that may be used for recursive creation of branch pipelines.

Parameters:

nestedRuleSets - A list of other RuleSet instances that are being used in conjunction with the PipelineRuleSet. In the case that branch pipelines are referred to by URI, these rule sets will be added to a new Digester instance (along with a PipelineRuleSet instance) that is used to parse the branch configuration file.

Method Detail

addRuleInstances

public void addRuleInstances(org.apache.commons.digester.Digester digester)

Adds the rule instances for pipeline, stage, and enqueue tasks to the Digester instance supplied.

Specified by:

addRuleInstances in interface org.apache.commons.digester.RuleSet

Specified by:

addRuleInstances in class org.apache.commons.digester.RuleSetBase

Parameters:

digester - The Digester instance to which the rules should be added.