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Extending RuntimeExecutableContentTransformer

This example extends the RuntimeExecutableContentTransformer using Spring configuration.

This code sample (tidyTransformer.xml) shows the required Spring configuration (tidyTransformer.xml) to extend the RuntimeExecutableContentTransformer. This is a standard transformer that can execute system executables. An example of a command line transformation program is HTML Tidy (http://tidy.sourceforge.net/), which can transform HTML documents into XHTML documents.

  1. Define the transformation command using the transformCommand property.

    The transformation mechanism substitutes the variables ${source} and ${target}, which are the full file paths of the source and target files for the transformation. For example:

          
        
    <property name="transformCommand">
        <bean class="org.alfresco.util.exec.RuntimeExec">
            <property name="commandMap">
                <map>
                    <entry key="Linux">
                        <value>tidy -asxhtml -o '${target}' '${source}'</value>
                    </entry>
                    <entry key="Windows.*">
                        <value>tidy -asxhtml -o "${target}" "${source}"</value>
                    </entry>
                </map>
            </property>
            ...
                
                
  2. (Optional) Define the checkCommand property.

    The optional checkCommand property feature comes with the transformer and is executed by the init method. If an error occurs during execution of this command, which cannot take any parameters, the transformer is flagged as unavailable. When unavailable, the getReliability method returns 0.0; otherwise it assumes that the transformation command will be successful. The reliability of the transformation is used by the transformation registry to select the most appropriate transformer for a given transformation. The transformer remains directly usable, such as if directly selected as an action to perform.

    External utilities stick to a rough convention regarding the return codes. In this case, tidy, returns a code value 2. The errorCodes property defines a comma-separated list of values indicating failure. The default is "1, 2".

    
    <property name="checkCommand">
     <bean class="org.alfresco.util.exec.RuntimeExec">
        <property name="commandMap">
            <map>
                <entry key=".*">
                    <value>tidy -help</value>
                </entry>
            </map>
        </property>
        <property name="errorCodes">
           <value>2</value>
        </property>
     </bean>
    </property>
          
          
  3. Define the MIME types this transformer supports using the explicitTransformations property.

    The transformer supports a source MIME type of text/html and a target MIME type of application/xhtml+xml.

                
        
    <property name="explicitTransformations">
     <list>
        <bean class="org.alfresco.repo.content.transform.ExplictTransformationDetails" >
            <property name="sourceMimetype"><value>text/html</value></property>
            <property name="targetMimetype"><value>application/xhtml+xml</value></property>
        </bean>
     </list>
    </property>
    
    
  4. Save your file to commit your changes, for example, as tidyTransformer.xml.
This illustrates how to extend an existing service by using configuration only by adding a new transformer without any code changes. To expose the new transformer by using the client interfaces or as a repository action requires additional configuration. The following shows the full code example used in this task.
    
<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE beans PUBLIC '-//SPRING//DTD BEAN//EN' 'http://www.springframework.org/dtd/spring-beans.dtd'>
<beans>
   <bean id="transformer.Tidy.XHTML" 
       class="org.alfresco.repo.content.transform.RuntimeExecutableContentTransformer" 
       parent="baseContentTransformer">
      <property name="checkCommand">
         <bean class="org.alfresco.util.exec.RuntimeExec">
            <property name="commandMap">
                <map>
                    <entry key=".*">
                        <value>tidy -help</value>
                    </entry>
                </map>
            </property>
            <property name="errorCodes">
               <value>2</value>
            </property>
         </bean>
      </property>
      <property name="transformCommand">
         <bean class="org.alfresco.util.exec.RuntimeExec">
            <property name="commandMap">
                <map>
                    <entry key="Linux">
                        <value>tidy -asxhtml -o '${target}' '${source}'</value>
                    </entry>
                    <entry key="Windows.*">
                        <value>tidy -asxhtml -o "${target}" "${source}"</value>
                    </entry>
                </map>
            </property>
            <property name="errorCodes">
               <value>2</value>
            </property>
         </bean>
      </property>
      <property name="explicitTransformations">
         <list>
            <bean class="org.alfresco.repo.content.transform.ExplictTransformationDetails" >
                <property name="sourceMimetype"><value>text/html</value></property>
                <property name="targetMimetype"><value>application/xhtml+xml</value></property>
            </bean>
         </list>
      </property>
   </bean>
</beans>

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