using IVY dependencies manager programmatically

Question

i need help using IVY as dependencies manager
my application need to load plug-ins at RUN-TIME
means while the core application is running ,user can request for a new plug-in
and install them ,
i wish to manage all installed plug-ins using the core application DB.

i want to get a pom from my plug-ins server (or some other descriptor),
and ask IVY to tell me what are the dependencies OR let IVY install the plug-in and dependencies , based on the current state of my application.

( what do i have right now ,
1.jar's used by core application
2.jar's used by current installed plug-ins)

i wish for each plug-in to have independent directory
under some folder where my application is located (not a shared one)

the thing is i don't know where to start
i notice that there is no programming API for that

i located one link over the network of someone who try something similar
but look likes the code is not completed , or some variable are missing and i dont know how to complete the rest cause lake of programming documentation
http://www.mail-archive.com/[e-mail]/msg03228.html (where the variable "art" came for.....)

can you help me please ... Thank you all

UPDATE

ok this what i am trying now . i am getting some a error plus i dont know how to define my archiva server

      IvySettings settings = new IvySettings();

     settings.setDefaultIvyUserDir(new File("D:/programming/eclipse_projects/ivyTest/repo/"));

      settings.setDefaultCache(new File("D:/programming/eclipse_projects/ivyTest/repo/cache/"));
      settings.setDefaultCacheArtifactPattern("[module]/[revision]/[module]-[revision](-[classifier]");

  Ivy ivy = Ivy.newInstance(settings);

  ivy.getLoggerEngine().pushLogger(new DefaultMessageLogger(Message.MSG_VERBOSE));

  ModuleDescriptor md =  PomModuleDescriptorParser.getInstance().parseDescriptor(new IvySettings(), new File("src/movies.pom").toURL(), true);

  RetrieveOptions retriveOptions = new RetrieveOptions();
  retriveOptions.setUseOrigin(true);
  retriveOptions.setConfs(md.getConfigurationsNames());
  ivy.retrieve(md.getModuleRevisionId(), "lib/[conf]/[artifact].[ext]", etriveOptions);

this is the error i get

:: loading settings :: url = jar:file:/D:/programming/eclipse_projects/ivyTest/ivy-2.2.0.jar!/org/apache/ivy/core/settings/ivysettings.xml
:: retrieving :: org.jtpc#movies
    checkUpToDate=true
    confs: [default, master, compile, provided, runtime, test, system, sources, javadoc, optional]
java.lang.RuntimeException: problem during retrieve of org.jtpc#movies: java.lang.IllegalStateException: Report file 'D:\programming\eclipse_projects\ivyTest\repo\cache\org.jtpc-movies-default.xml' does not exist.
    at org.apache.ivy.core.retrieve.RetrieveEngine.retrieve(RetrieveEngine.java:206)
    at org.apache.ivy.Ivy.retrieve(Ivy.java:540)
    at Test.main(Test.java:52)
Caused by: java.lang.IllegalStateException: Report file 'D:\programming\eclipse_projects\ivyTest\repo\cache\org.jtpc-movies-default.xml' does not exist.
    at org.apache.ivy.plugins.report.XmlReportParser.parse(XmlReportParser.java:294)
    at org.apache.ivy.core.retrieve.RetrieveEngine.determineArtifactsToCopy(RetrieveEngine.java:288)
    at org.apache.ivy.core.retrieve.RetrieveEngine.retrieve(RetrieveEngine.java:104)
    ... 2 more

Answer 1

Ivy can be used as a standalone java program:

java -jar ivy.jar -retrieve "lib/[conf]/[artifact].[ext]"

The retrieve pattern can be then used to determine where files are installed, based on the ivy configuration settings

$ find lib -type f
lib/core/commons-lang.jar
lib/plugin1/commons-logging.jar
lib/plugin1/commons-codec.jar
lib/plugin2/commons-logging.jar
lib/plugin2/commons-cli.jar
lib/plugin3/commons-logging.jar

Configurations are used as a collective label or grouping of dependencies. They are similar to Maven scopes but much more flexible:

<ivy-module version="2.0">
    <info organisation="com.myspotontheweb" module="demo"/>
    <configurations>
        <conf name="core"    description="Core application dependencies"/>
        <conf name="plugin1" description="Plugin 1 dependencies"/>
        <conf name="plugin2" description="Plugin 2 dependencies"/>
        <conf name="plugin3" description="Plugin 3 dependencies"/>
    </configurations>
    <dependencies>
        <dependency org="commons-lang"    name="commons-lang"    rev="2.5"   conf="core->default"/>
        <dependency org="commons-codec"   name="commons-codec"   rev="1.4"   conf="plugin1->default"/>
        <dependency org="commons-cli"     name="commons-cli"     rev="1.2"   conf="plugin2->default"/>
        <dependency org="commons-logging" name="commons-logging" rev="1.1.1" conf="plugin1,plugin2,plugin3->default"/>
    </dependencies>
</ivy-module>

If you only want to download and install one set of jars, into a specified directory you can use the confs parameter:

java -jar ivy.jar -retrieve "plugin1/[artifact].[ext]" -confs plugin1

Finally, if you still want to use a programming API, you could invoke the run method called by the main class

http://svn.apache.org/viewvc/ant/ivy/core/trunk/src/java/org/apache/ivy/Main.java?view=markup

Update 1

Groovy has built in support for invoking ivy tasks

import groovy.xml.NamespaceBuilder

def ant = new AntBuilder()
def ivy = NamespaceBuilder.newInstance(ant, 'antlib:org.apache.ivy.ant')

ivy.settings(file:"ivysettings.xml")
ivy.retrieve(pattern:"lib/[conf]/[artifact].[ext]")
ivy.report(toDir:'reports', graph:false) 

Update 2

To set the location of your local Maven repository you need to use an ivysettings.xml file.

<ivysettings>
  <settings defaultResolver='nexus' />
  <resolvers>
    <ibiblio name='nexus' root='http://myhost.mydomanin.com:8081/nexus' m2compatible='true' />
  </resolvers>
</ivysettings>

Update 3

Just found an article that details how to invoke Ivy from Java