5.3. ChangeSets

5.3.1. Changesets

The changeset feature facilitates the building of knowledge bases without using the API. Changesets can include any number of resources. They can also support additional configuration information, which currently is only needed for decision tables.
The file changeset.xml contains a list of resources for this. It can also point recursively to another changeset XML file.
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5.3.2. Changeset Example

A resource approach is employed that uses a prefix to indicate the protocol. All the protocols provided by java.net.URL, such as "file" and "http", are supported, as well as an additional "classpath". Currently the type attribute must always be specified for a resource, as it is not inferred from the file name extension. This is demonstrated in the example below: 
<change-set xmlns='http://drools.org/drools-5.0/change-set'
             xmlns:xs='http://www.w3.org/2001/XMLSchema-instance'
             xs:schemaLocation='http://drools.org/drools-5.0/change-set http://anonsvn.jboss.org/repos/labs/labs/jbossrules/trunk/drools-api/src/main/resources/change-set-1.0.0.xsd' >
   <add>
       <resource source='http:org/domain/myrules.drl' type='DRL' />
   </add>
 </change-set>
The above example can be used by changing the resource type to CHANGE_SET: 
KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();
kbuilder.add( ResourceFactory.newClasspathResource( "myChangeSet.xml", getClass() ),
              ResourceType.CHANGE_SET );
if ( kbuilder.hasErrors() ) {
    System.err.println( builder.getErrors().toString() );
}
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5.3.3. Extended Changeset Example

ChangeSets can include any number of resources, and they even support additional configuration information, which is only currently needed for decision tables. The example below is expanded to load the rules from a http URL location, and an Excel decision table from the classpath: 
<change-set xmlns='http://drools.org/drools-5.0/change-set'
             xmlns:xs='http://www.w3.org/2001/XMLSchema-instance'
             xs:schemaLocation='http://drools.org/drools-5.0/change-set.xsd http://anonsvn.jboss.org/repos/labs/labs/jbossrules/trunk/drools-api/src/main/resources/change-set-1.0.0.xsd' >
   <add>
       <resource source='http:org/domain/myrules.drl' type='DRL' />
       <resource source='classpath:data/IntegrationExampleTest.xls' type="DTABLE">
           <decisiontable-conf input-type="XLS" worksheet-name="Tables_2" />
       </resource>
   </add>
 </change-set>
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5.3.4. Changesets and Directories Example

You can specify a directory to put content into. It is expected that all the files are of the specified type, since type is not yet inferred from the file name extensions: 
<change-set xmlns='http://drools.org/drools-5.0/change-set'
             xmlns:xs='http://www.w3.org/2001/XMLSchema-instance'
             xs:schemaLocation='http://drools.org/drools-5.0/change-set.xsd http://anonsvn.jboss.org/repos/labs/labs/jbossrules/trunk/drools-api/src/main/resources/change-set-1.0.0.xsd' >
   <add>
       <resource source='file://myfolder/' type='DRL' />
   </add>
 </change-set>
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5.3.5. Building Using Configuration and the ChangeSet XML

You can create definitions using a configuration within the ChangeSet XML. The simple XML file supports three elements: add, remove, and modify. Each of these have a sequence of <resource> subelements defining a configuration entity.
The following example is a none-normative XML schema ChangeSet: 
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
           xmlns="http://drools.org/drools-5.0/change-set"
           targetNamespace="http://drools.org/drools-5.0/change-set">

  <xs:element name="change-set" type="ChangeSet"/>

  <xs:complexType name="ChangeSet">
    <xs:choice maxOccurs="unbounded">
      <xs:element name="add"    type="Operation"/>
      <xs:element name="remove" type="Operation"/>
      <xs:element name="modify" type="Operation"/>
    </xs:choice>
  </xs:complexType>

  <xs:complexType name="Operation">
    <xs:sequence>
      <xs:element name="resource" type="Resource"
                  maxOccurs="unbounded"/>
    </xs:sequence>
  </xs:complexType>

  <xs:complexType name="Resource">
    <xs:sequence>
      <!-- To be used with <resource type="DTABLE"...> -->
      <xs:element name="decisiontable-conf" type="DecTabConf"
                  minOccurs="0"/>
    </xs:sequence>
    <!-- java.net.URL, plus "classpath" protocol -->
    <xs:attribute name="source" type="xs:string"/>
    <xs:attribute name="type"   type="ResourceType"/>
  </xs:complexType>

  <xs:complexType name="DecTabConf">
    <xs:attribute name="input-type"     type="DecTabInpType"/>
    <xs:attribute name="worksheet-name" type="xs:string"
                  use="optional"/>
  </xs:complexType>

  <!-- according to org.drools.builder.ResourceType -->
  <xs:simpleType name="ResourceType">
    <xs:restriction base="xs:string">
      <xs:enumeration value="DRL"/>
      <xs:enumeration value="XDRL"/>
      <xs:enumeration value="DSL"/>
      <xs:enumeration value="DSLR"/>
      <xs:enumeration value="DRF"/>
      <xs:enumeration value="DTABLE"/>
      <xs:enumeration value="PKG"/>
      <xs:enumeration value="BRL"/>
      <xs:enumeration value="CHANGE_SET"/>
    </xs:restriction>
  </xs:simpleType>

  <!-- according to org.drools.builder.DecisionTableInputType -->
  <xs:simpleType name="DecTabInpType">
    <xs:restriction base="xs:string">
      <xs:enumeration value="XLS"/>
      <xs:enumeration value="CSV"/>
    </xs:restriction>
  </xs:simpleType>

</xs:schema>

Note

Please note, the previous XML schema is for illustration purposes.
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5.3.6. ChangeSet XML Example

This is an example of a basic ChangeSet XML schema that loads a single DRL file: 
<change-set xmlns='http://drools.org/drools-5.0/change-set'
             xmlns:xs='http://www.w3.org/2001/XMLSchema-instance'
             xs:schemaLocation='http://drools.org/drools-5.0/change-set.xsd http://anonsvn.jboss.org/repos/labs/labs/jbossrules/trunk/drools-api/src/main/resources/change-set-1.0.0.xsd' >
   <add>
      <resource source='file:/project/myrules.drl' type='DRL' />
   </add>
</change-set>
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5.3.7. ChangeSet Protocols

The ChangeSet supports all the protocols provided by java.net.URL, such as "file" and "http", as well as an additional "classpath". The type attribute must always be specified for a resource, as it is not inferred from the file name extension.
Use the file: prefix to signify the protocol for the resource.

Note

When using XML schema, the Class Loader will default to the one used by the Knowledge Builder unless the ChangeSet XML is itself loaded by the ClassPath resource, in which case it will use the Class Loader specified for that resource.
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5.3.8. Loading the ChangeSet XML

Procedure 5.4. Task

  1. Use the API to load your ChangeSet.
  2. Use this code to access the ChangeSet XML: 
    kbuilder.add( ResourceFactory.newUrlResource( url ), ResourceType.CHANGE_SET );
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5.3.9. ChangeSet XML with Resource Configuration Example

This example shows you how to incorporate resource configuration in your ChangeSet: 
 <change-set xmlns='http://drools.org/drools-5.0/change-set'
             xmlns:xs='http://www.w3.org/2001/XMLSchema-instance'
             xs:schemaLocation='http://drools.org/drools-5.0/change-set.xsd http://anonsvn.jboss.org/repos/labs/labs/drools/trunk/drools-api/src/main/resources/change-set-1.0.0.xsd' >
  <add>
       <resource source='http:org/domain/myrules.drl' type='DRL' />
       <resource source='classpath:data/IntegrationExampleTest.xls' type="DTABLE">
           <decisiontable-conf input-type="XLS" worksheet-name="Tables_2" />
       </resource>
   </add>
 </change-set>
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5.3.10. ChangeSet XML and Directories

The following code allows you to add a directory's contents to the ChangeSet: 
<change-set xmlns='http://drools.org/drools-5.0/change-set'
            xmlns:xs='http://www.w3.org/2001/XMLSchema-instance'
            xs:schemaLocation='http://drools.org/drools-5.0/change-set.xsd http://anonsvn.jboss.org/repos/labs/labs/drools/trunk/drools-api/src/main/resources/change-set-1.0.0.xsd' >
   <add>
      <resource source='file:/projects/myproject/myrules' type='DRL' />
   </add>
</change-set>

Note

Currently it is expected that all resources in that folder are of the same type. If you use the Knowledge Agent it will provide a continuous scanning for added, modified or removed resources and rebuild the cached Knowledge Base.
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