GeneratorOnExtension

I had a lot of similar pipelines being different only in the generator stage.

So I've created a custom selector, that reports if a file with the given extension exists in the configured path.

Here is its source code (quite simple):

Source code

{{{package es.fcc.cocoon;

import java.io.File; import java.util.Map;

import org.apache.avalon.framework.logger.AbstractLogEnabled; import org.apache.avalon.framework.parameters.ParameterException; import org.apache.avalon.framework.parameters.Parameters; import org.apache.cocoon.environment.ObjectModelHelper; import org.apache.cocoon.selection.Selector;

public class ExtensionSelector extends AbstractLogEnabled implements Selector {

• /** @see org.apache.cocoon.selection.Selector#select(java.lang.String, java.util.Map, org.apache.avalon.framework.parameters.Parameters) */ public boolean select(String expression, Map objectModel, Parameters parameters) {

  • String path = parameters.getParameter("path", null); if (path == null) {
    • getLogger().warn("Unspecified path parameter"); return false;
    }

    path = ObjectModelHelper.getContext(objectModel).getRealPath("/")+path+"."+expression; if (getLogger().isDebugEnabled()) {

    • getLogger().debug("Looking for the existence of "+path);
    } return new File(path).isFile();
  }

} }}}

Declaration

Here is how the component is declared in the sitemap:

<map:selector name="extension"src="es.fcc.cocoon.ExtensionSelector"/>

Pipeline usage

And finally how it is used in a pipeline:

<map:match pattern="**/*.frm">
        <map:select type="extension">
                <!--Tell our custom action the path where to search in-->
                <map:parameter name="path" value="{1}/{2}"/>
                        <map:when test="xsp">
                                <!--Map xsp extension to serverpages generator-->
                                <map:generate type="serverpages" src="{1}/{2}.xsp"/>
                        </map:when>
                        <map:when test="xml">
                                <!--Map xml extension to default file generator-->
                                <map:generate src="{1}/{2}.xml"/>
                        </map:when>
                        <map:otherwise>
                                <!--Unknown generator-->
                        </map:otherwise>
                </map:select>
        </map:select>
        <!--The pipeline processing continues here-->
</map:match>

In this way we can change the type the generator by simply changing the source filename extension and without bothering updating the sitemap, and uniformizing complicated pipelines and sub-pipelines.

Comments are welcome!

Comment: Good idea, not that good implementation. Issues are:

• Use of get!RealPath(). This method must be avoided at all costs

• Will not work in sub-sitemaps (because of get!RealPath('/'))

• Will not work in WAR, EAR files (because of File)

See ResourceExistsAction for an inspiration for better implementation. --Vadim