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Message-ID: <00af01c15575$f4f16580$0100a8c0@jose>
From: "Jose Alberto Fernandez" <j_a_fernandez@yahoo.com>
To: <ant-dev@jakarta.apache.org>
References: <F483AD0DB13BD411A38300104B2E651E8F0EB6@valkyrie.wamnet.com>
Subject: Re: SUMMARY: loading tasks from jars for Ant 1.5 summary feedback
Date: Mon, 15 Oct 2001 13:36:03 +0100
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From: "Tim Dawson" <tdawson@wamnet.com>

> > From: Jose Alberto Fernandez [mailto:j_a_fernandez@yahoo.com]
> >=20
>=20
> ok... then how do we get the DD? (I've only ever used getResources()
> to grab a resource other than a properties file from a jar)
>=20
> I'm gonna need a few implementation pointers here...

You could just extracted from the library using the Zip classes.=20
>=20
> I can agree with that 100%.  Is using "Class-Path" controversial?
> I haven't read any threads related to that.
>=20

The problem that I see here is that ANT is using its own 1.1 able =
ClassLoader
which do not understant Class-Path. Which it is a problem. I think we =
would have to
retrofit the details of the 1.2 spec into AntClassLoader to make it work =
right.
Notice that 1.2 provides URLClassLoader which knows how to do all the =
work.
I think.

> I could see how it would be for the optional jar, because there
> are so many different dependencies locked up in there, you'd have
> to break it out into many smaller jars or else I'd have to have
> the starteam.jar even though all I want is to use the junit task.
>=20

In my understading, not everything in Class-Path needs to exest. Same as =
with CLASSPATH.

I think though that is would be a very good idea to break up =
optional.jar into a bunch of
smaller libraries for each particular usage. For example an AntCVS.jar, =
AntPCVS.jar, AntJunit.jar
ans so on. Each with its limited dependencies. So in your buildfile you =
would say:
    <antlib library=3D"AntJunit.jar"/>
and we will just need to have junit.jar is you want this library to =
work.

> >=20
> > But that would mean there is no way to start ANT, just because=20
> > you put one too many jars in the system. That sounds really bad to =
me.
>=20
> ah, I see what you mean. if I dropped the jar file in I'd still get an
> error whether or not I was planning to use it. that would be =
confusing.
>=20
> the best approach is just to unsupport autoloading. I'm in support of =
that,
> but can we get consensus around it?
>=20

Agreed.

Tim, I have been working on an implementation which I think is all coded =
but I have not tested yet.
Before sending a patch submission I also want to have an <antjar> task =
to package=20
the libraries and verify the descriptor. Only after that, I would try to =
submit a patch of core to
reorganize it in libraries, and adopt it during initial loading.

I am attaching the code I have to hear your suggestions or anyone elses =
on the code I have.

My goal at the end of the day is for the core to load its core tasks by =
just executing the equivalent of
<antlib library=3D"ant.jar" />.
One of the problems I am trying to dealt with is how to bootstrap ANT in =
this new model.=20
During bootstrapping (when building from scratch) there is no "ant.jar" =
and hence the problem.
If there is no /org/apache/tools/ant/defaults.properties, but instead =
one of several META-INF/antlib.xml=20
we will need some way to tell ANT to use the unjared file located =
somewhere.
I was thinking on adding a property during bootstrap:
    -Dant.bootxml=3D"filename"=20
which will be used by the core instead of the <antlib> mentioned above. =
You will see some methods in the code
providing what it is needed for this to work.

I would like your opinionsand improvements. This code depends on the =
patch for project-level tasks (DeclaringTasks) that I sent last week.

Hope to hear comments, concerns, additions, etc.

Jose Alberto



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	name="Antlib.java"
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/*
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights=20
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.=20
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement: =20
 *       "This product includes software developed by the=20
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software =
itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Ant", and "Apache Software
 *    Foundation" must not be used to endorse or promote products =
derived
 *    from this software without prior written permission. For written=20
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * =
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package org.apache.tools.ant.taskdefs;

import org.apache.tools.ant.*;
import org.apache.tools.ant.types.*;
import org.xml.sax.*;
import javax.xml.parsers.*;

import java.util.*;
import java.util.zip.*;
import java.io.*;

/**
 * Make available the tasks and types from an Ant library.
 *
 * <pre>
 * &lt;antlib library=3D"libname.jar" &gt;
 *   &lt;alias name=3D"nameOnLib" as=3D"newName" /&gt;
 * &lt;/antlib&gt;
 *=20
 * &lt;antlib file=3D"libname.jar" override=3D"true" /&gt;
 * </pre>
 * @author <a href=3D"j_a_fernandez@yahoo.com">Jose Alberto =
Fernandez</a>
 */
public class Antlib extends Task implements DeclaringTask {

    /** Location of destriptor in library */
    public static String XML_DESCRIPTOR =3D    "META-INF/antlib.xml";

    /** Prefix name for DTD of descriptor */
    public static String ANTLIB_DTD_PREFIX =3D "Antlib-V";
    public static String ANTLIB_DTD_EXT =3D    ".dtd";

    private String library =3D null;
    private File file =3D null;
    private boolean override =3D false;
    private boolean onCurrent =3D false;

    private SAXParserFactory saxFactory;
    private Vector aliases =3D new Vector();

    public class Alias {
	private String name;
	private String as;

	public void setName(String name) {
	    this.name =3D name;
	}

	public void setAs(String as) {
	    this.as =3D as;
	}
    }

    public Antlib() {
	super();
	saxFactory  =3D SAXParserFactory.newInstance();
	saxFactory.setValidating(true);
    }

    public Antlib(Project p) {
	this();
	setProject(p);
    }

    /**=20
     * Set name of library to load. The library is located in =
$ANT_HOME/lib.
     * @param lib the name of library relative to $ANT_HOME/lib.
     */
    public void setLibrary(String lib) {
	this.library =3D lib;
    }

    /**
     * Set file location of library to load.
     * @param file the jar file for the library.
     */
    public void setFile(File file) {
	this.file =3D file;
    }

    /**
     * Set whether to override any existing definitions.
     * @param override if true new definitions will replace existing =
ones.
     */
    public void setOverride(boolean override) {
	this.override =3D override;
    }

    /**
     * Set whether to use a new classloader or not.=20
     * Default is <code>false</code>.
     * This property is mostly used by the core when loading core tasks.
     * @param onCurrent if true the current classloader will be used to
     *                  load the definitions.
     */
    public void setOnCurrent(boolean onCurrent) {
	this.onCurrent =3D onCurrent;
    }

    /** Create new Alias element. */
    public Alias createAlias() {
	Alias als =3D new Alias();
	aliases.add(als);
	return als;
    }

    public void execute() throws BuildException {
	File realFile =3D file;
	if (library !=3D null) {
	    if (file !=3D null) {
		String msg =3D "You cannot specify both file and library.";
		throw new BuildException(msg, location);
	    }
	    // For the time being libraries live in $ANT_HOME/lib.
	    // The idea being that we would not load all the jar there anymore
	    String home =3D project.getProperty("ant.home");
	   =20
	    if (home =3D=3D null)
		throw new BuildException("ANT_HOME not set as required.");

	    realFile =3D new File(new File(home, "lib"), library);
	}
	else if (file =3D=3D null) {
	    String msg =3D "Must specify either library or file attribute.";
	    throw new BuildException(msg, location);
	}
	if (!realFile.exists()) {
	    String msg =3D "Cannot find library: " + realFile;
	    throw new BuildException(msg, location);
	}

	InputStream is =3D getDescriptor(realFile);
=09
	if (is =3D=3D null) {
	    String msg =3D "Missing descriptor on library: " + realFile;
	    throw new BuildException(msg, location);
	}

	evaluateDescriptor(onCurrent? null : makeClassLoader(realFile),=20
			   processAliases(), is);
    }

    /**
     * Load definitions directly from an external XML file.
     * @param xmlfile XML file in the Antlib format.
     */
    public void loadDefinitions(File xmlfile) throws BuildException {
	try {
	    InputStream is =3D new FileInputStream(xmlfile);
	    loadDefinitions(is);
	}
	catch (IOException io) {
	    throw new BuildException("Cannot read file: " + file, io);
	}
    }

    /**
     * Load definitions directly from InputStream.
     * @param is InputStream for the Antlib descriptor.
     */
    public void loadDefinitions(InputStream is) throws BuildException {
	evaluateDescriptor(null, processAliases(), is);
    }

    private InputStream getDescriptor(File file) {
	try {
	    final ZipFile zipfile =3D new ZipFile(file);
	    ZipEntry entry =3D zipfile.getEntry(XML_DESCRIPTOR);
	   =20
	    if (entry =3D=3D null) return null;
	   =20
	    // Guarantee that when Entry is close so does the zipfile instance.
	    return new FilterInputStream(zipfile.getInputStream(entry)){
		public void close() throws IOException {
		    super.close();
		    zipfile.close();
		}
	    };
	}
	catch(ZipException ze) {
	    throw new BuildException("Not a library file.", ze, location);
	}
	catch(IOException ioe) {
	    throw new BuildException("Cannot read library content.",
				     ioe, location);
	}
    }

    private Properties processAliases() {
	Properties p =3D new Properties();

	for(Enumeration e =3D aliases.elements(); e.hasMoreElements();) {
	    Alias a =3D (Alias)e.nextElement();
	    p.put(a.name, a.as);
	}
	return p;
    }

    protected ClassLoader makeClassLoader(File fl) throws BuildException =
{
	Path clspath =3D new Path(project);
	clspath.setLocation(fl);
	AntClassLoader al =3D new AntClassLoader(project, clspath, true);
	return al;
    }

    protected void evaluateDescriptor(ClassLoader cl,=20
				      Properties als, InputStream is)
	throws BuildException
    {
	try {
            SAXParser saxParser =3D saxFactory.newSAXParser();
            Parser parser =3D saxParser.getParser();

            InputSource inputSource =3D new InputSource(is);
            //inputSource.setSystemId(uri); //URI is nasty for jar =
entries
            project.log("parsing descriptor for library: " + file,=20
			Project.MSG_VERBOSE);
            saxParser.parse(inputSource, new AntLibraryHandler(cl, =
als));
        }
        catch(ParserConfigurationException exc) {
            throw new BuildException("Parser has not been configured =
correctly", exc);
        }
        catch(SAXParseException exc) {
            Location location =3D
                new Location(XML_DESCRIPTOR,=20
			     exc.getLineNumber(), exc.getColumnNumber());

            Throwable t =3D exc.getException();
            if (t instanceof BuildException) {
                BuildException be =3D (BuildException) t;
                if (be.getLocation() =3D=3D Location.UNKNOWN_LOCATION) {
                    be.setLocation(location);
                }
                throw be;
            }
           =20
            throw new BuildException(exc.getMessage(), t, location);
        }
        catch(SAXException exc) {
            Throwable t =3D exc.getException();
            if (t instanceof BuildException) {
                throw (BuildException) t;
            }
            throw new BuildException(exc.getMessage(), t);
        }
        catch(IOException exc) {
            throw new BuildException("Error reading library descriptor", =
exc);
        }
        finally {
            if (is !=3D null) {
                try {
                    is.close();
                }
                catch (IOException ioe) {
                    // ignore this
                }
            }
        }
    }

    /**
     * Parses the document describing the content of the library.
     */
    private class AntLibraryHandler extends HandlerBase {
=09
	private final ClassLoader cl;
	private final Properties aliasMap;
	private Locator locator =3D null;

	AntLibraryHandler(ClassLoader cl, Properties als) {
	    this.cl =3D cl;
	    this.aliasMap =3D als;
	}

        public void setDocumentLocator(Locator locator) {
            this.locator =3D locator;
        }

	public void startElement(String tag, AttributeList attrs)
	    throws SAXParseException=20
	{
	    if ("antlib".equals(tag)) {
		// No attributes to worry about
		return;
	    }
	    if ("task".equals(tag) || "type".equals(tag)) {
		String name =3D null;
		String className =3D null;

		for (int i =3D 0, last =3D attrs.getLength(); i < last; i++) {
		    String key =3D attrs.getName(i);
		    String value =3D attrs.getValue(i);

		    if (key.equals("name")) {
			name =3D value;
		    } else if (key.equals("class")) {
			className =3D value;
		    } else {
			throw new SAXParseException("Unexpected attribute \""=20
						    + key + "\"", locator);
		    }
		}
		if (name =3D=3D null || className =3D=3D null) {
		    String msg =3D "Underspecified " + tag + " declaration.";
		    throw new SAXParseException(msg, locator);
		}
	=09
		try {
		    String alias =3D aliasMap.getProperty(name);

		    if (alias !=3D null) name =3D alias;
		    if (!override && inUse(name)) {
			String msg =3D "Cannot override " + tag + ": " + name;
			log(msg, Project.MSG_WARN);
			return;
		    }

		    Class cls =3D (cl !=3D null)?=20
			cl.loadClass(className) : Class.forName(className);

		    if (tag.equals("task")) {
			project.addTaskDefinition(name, cls);
		    } else {
			project.addDataTypeDefinition(name, cls);
		    }
		} catch (ClassNotFoundException cnfe) {
		    String msg =3D "Class " + className +
			" cannot be found";
		    throw new SAXParseException(msg, locator, cnfe);
		} catch (NoClassDefFoundError ncdfe) {
		    String msg =3D "Class " + className +
			" cannot be found";
		    throw new SAXParseException(msg, locator);
		}
	    }=20
	    else {
		throw new SAXParseException("Unexpected element \"" +=20
					    tag + "\"",=20
					    locator);
	    }
	}

	private boolean inUse(String name) {
	    return (project.getTaskDefinitions().get(name) !=3D null ||
		    project.getDataTypeDefinitions().get(name) !=3D null);
	}

	/**
	 * Recognizes the DTD declaration for antlib and returns
	 * the corresponding DTD definition from a resource.
	 * <P>
	 * To allow for future versions of the DTD format it will
	 * search for any DTDs of the form "Antlib-V.*\.dtd".
	 */
        public InputSource resolveEntity(String publicId,
                                         String systemId) {
       =20
	    if (systemId !=3D null &&
		systemId.startsWith(ANTLIB_DTD_PREFIX) &&
		systemId.endsWith(ANTLIB_DTD_EXT)) {
		InputSource is =3D
		    new InputSource(getClass().getResourceAsStream(systemId));

		is.setSystemId(systemId);
		return is;
	    }
	    return null;
	}
    }
}



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	name="Antlib-V1_0.dtd"
Content-Transfer-Encoding: 7bit
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	filename="Antlib-V1_0.dtd"

<?xml version='1.0'?>

<!-- 
This file defines the XML format for ANT library descriptors.
Descriptors must especify a DOCTYPE using "Antlib-V1_0.dtd"
as the SystemId for the document.
-->

<!-- Root element for the Antlib descriptor.                 -->
<!ELEMENT antlib (task | type)* >
<!ATTLIST antlib
          version  CDATA #IMPLIED
>

<!-- Declaration of tasks contained in the library.          -->
<!ELEMENT task EMPTY>
<!ATTLIST task 
          name     CDATA #REQUIRED
          class    CDATA #REQUIRED
>

<!-- Declaration of datatypes contained in the library       -->
<!ELEMENT type EMPTY>
<!ATTLIST type 
          name     CDATA #REQUIRED
          class    CDATA #REQUIRED
>

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