Project dependencies


This tutorial will show you how to use Ivy when one of your projects depends on another.

For our example, we will have two projects, depender and dependee, where the depender project uses/requires the dependee project. This example will help illustrate two things about Ivy:
  • that dependencies defined by parent projects (dependee) will automatically be retrieved for use by child projects (depender)
  • that child projects can retrieve the "latest" version of the dependee project

projects used

dependee

The dependee project is very simple. It depends on the apache library commons-lang and contains only one class: standalone.Main which provides two services:
  • return the version of the project
  • capitalize a string using org.apache.commons.lang.WordUtils.capitalizeFully
Here is the content of the project:
  • build.xml: the ant build file for the project
  • ivy.xml: the project ivy file
  • src\standalone\Main.java: the only class of the project
Take a look at the ivy.xml file: 
<ivy-module version="1.0">
    <info organisation="org.apache" module="dependee"/>
    <dependencies>
        <dependency org="commons-lang" name="commons-lang" rev="2.0"/>
    </dependencies>
</ivy-module>
The ivy file declares only one dependency, that being the apache commons-lang library.

depender

The depender project is very simple as well. It declares only one dependency on the latest version of the dependee project, and it contains only one class, depending.Main, which does 2 things:
  • gets the version of the standalone project by calling standalone.Main.getVersion()
  • transforms a string by calling standalone.Main.capitalizeWords(str)
Take a look at the ivy.xml file: 
<ivy-module version="1.0">
    <info organisation="org.apache" module="depender"/>
    <dependencies>
        <dependency name="dependee" rev="latest.integration" />
    </dependencies>
</ivy-module>

settings

The Ivy settings are defined in two files located in the settings directory:
  • ivysettings.properties: a property file
  • ivysettings.xml: the file containing the settings
Let's have a look at the ivysettings.xml file: 
<ivysettings>
	<properties file="${ivy.settings.dir}/ivysettings.properties"/>
	<settings defaultResolver="libraries" />
	<caches defaultCacheDir="${ivy.settings.dir}/ivy-cache" />
	<resolvers>
		<filesystem name="projects">
			<artifact pattern="${repository.dir}/[artifact]-[revision].[ext]" />
			<ivy pattern="${repository.dir}/[module]-[revision].xml" />
		</filesystem>
		<ibiblio name="libraries" m2compatible="true" usepoms="false" />
	</resolvers>
	<modules>
		<module organisation="org.apache" name="dependee" resolver="projects"/>
	</modules>
</ivysettings>
The file contains four main tags: properties, settings, resolvers and modules.

properties

This tag loads some properties for the Ivy process, just like Ant does.

settings

This tag initializes some parameters for the Ivy process. In this case, the directory that Ivy will use to cache artifacts will be in a sub directory called ivy-cache of the directory containing the ivysettings.xml file itself.
The second parameter, tells Ivy to use a resolver named "libraries" as its default resolver. More information can be found in the settings reference documentation.

resolvers

This tag defines the resolvers to use. Here we have two resolvers defined: "projects" and "libraries".
The filesystem resolver called "projects" is able to resolve the internal dependencies by locating them on the local filesystem.
The ibiblio resolver called "libraries" is able to find dependencies on the maven 2 repository, but doesn't use maven poms.

modules

The modules tag allows you to configure which resolver should be used for which module. Here the setting tells Ivy to use the "projects" resolver for all modules having an organisation of org.apache and module name of dependee. This actually corresponds to only one module, but a regular expression could be used, or many other types of expressions (like glob expressions).

All other modules (i.e. all modules but org.apache#dependee), will use the default resolver ("libraries").

walkthrough

step 1: preparation

Open a DOS or shell window, and go to the src/example/dependence directory.

step 2: clean directory tree

On the prompt type: ant This will clean up the entire project directory tree. You can do this each time you want to clean up this example.

step 3: publication of dependee project

Go to dependee directory and publish the project 
[ivy@apache:/ivy/dependence/dependee]$ ant publish
Buildfile: /ivy/dependence/dependee/build.xml

resolve:
[ivy:retrieve] :: Apache Ivy 2.3.0 - 20130110142753 :: http://ant.apache.org/ivy/ ::
[ivy:retrieve] :: loading settings :: file = /ivy/dependence/settings/ivysettings.xml
[ivy:retrieve] :: resolving dependencies :: org.apache#dependee;working@apache
[ivy:retrieve] 	confs: [default]
[ivy:retrieve] 	found commons-lang#commons-lang;2.0 in libraries
[ivy:retrieve] downloading http://repo1.maven.org/maven2/commons-lang/commons-lang/2.0/commons-lang-2.0.jar ...
[ivy:retrieve] ...................... (165kB)
[ivy:retrieve] .. (0kB)
[ivy:retrieve] 	[SUCCESSFUL ] commons-lang#commons-lang;2.0!commons-lang.jar (468ms)
[ivy:retrieve] :: resolution report :: resolve 234ms :: artifacts dl 468ms
	---------------------------------------------------------------------
	|                  |            modules            ||   artifacts   |
	|       conf       | number| search|dwnlded|evicted|| number|dwnlded|
	---------------------------------------------------------------------
	|      default     |   1   |   1   |   0   |   0   ||   1   |   1   |
	---------------------------------------------------------------------
[ivy:retrieve] :: retrieving :: org.apache#dependee
[ivy:retrieve] 	confs: [default]
[ivy:retrieve] 	1 artifacts copied, 0 already retrieved (165kB/16ms)

compile:
    [mkdir] Created dir: /ivy/dependence/dependee/build/classes
    [javac] Compiling 1 source file to /ivy/dependence/dependee/build/classes

jar:
[propertyfile] Creating new property file: /ivy/dependence/dependee/build/classes/version.properties
      [jar] Building jar: /ivy/dependence/dependee/build/dependee.jar

publish:
[ivy:publish] :: delivering :: org.apache#dependee;working@apache :: 1 :: release :: Thu Jan 10 14:34:36 CET 2013
[ivy:publish] 	delivering ivy file to /ivy/dependence/dependee/build/ivy.xml
[ivy:publish] :: publishing :: org.apache#dependee
[ivy:publish] 	published dependee to /ivy/dependence/settings/repository/dependee-1.jar
[ivy:publish] 	published ivy to /ivy/dependence/settings/repository/dependee-1.xml
     [echo] project dependee released with version 1

BUILD SUCCESSFUL
Total time: 2 seconds
What we see here:
  • the project depends on 1 library (1 artifact)
  • the library was not in the Ivy cache and so was downloaded (1 downloaded)
  • the project has been released under version number 1
As you can see, the call to the publish task has resulted in two main things:
  • the delivery of a resolved ivy file to build/ivy.xml.
    • This has been done because by default, the publish task not only publishes artifacts, but also its ivy file. So it has looked to the path where the ivy file to publish should be, using the artifactspattern: ${build.dir}/[artifact].[ext]. For an ivy file, this resolves to build/ivy.xml. Because this file does not exist, it automatically makes a call to the deliver task which delivers a resolved ivy file to this destination.
  • the publication of artifact 'dependee' and its resolved ivy file to the repository.
    • Both are just copies of the files found in the current project, or more precisely, those in the build directory. This is because the artifactspattern has been set to ${build.dir}/[artifact].[ext], so the dependee artifact is found at build/dependee.jar and the ivy file in build/ivy.xml. And because we have asked the publish task to publish them using the "projects" resolver, these files are copied to repository\dependee-1.jar and to repository\dependee-1.xml, respecting the artifact and ivy patterns of our settings (see above).

step 4: running the depender project

Go to directory depender and run ant 
[ivy@apache:/ivy/dependence/depender]$ ant 
Buildfile: /ivy/dependence/depender/build.xml

clean:

resolve:
[ivy:retrieve] :: Apache Ivy 2.3.0 - 20130110142753 :: http://ant.apache.org/ivy/ ::
[ivy:retrieve] :: loading settings :: file = /ivy/dependence/settings/ivysettings.xml
[ivy:retrieve] :: resolving dependencies :: org.apache#depender;working@apache
[ivy:retrieve] 	confs: [default]
[ivy:retrieve] 	found org.apache#dependee;1 in projects
[ivy:retrieve] 	[1] org.apache#dependee;latest.integration
[ivy:retrieve] 	found commons-lang#commons-lang;2.0 in libraries
[ivy:retrieve] downloading /ivy/dependence/settings/repository/dependee-1.jar ...
[ivy:retrieve] .. (1kB)
[ivy:retrieve] .. (0kB)
[ivy:retrieve] 	[SUCCESSFUL ] org.apache#dependee;1!dependee.jar (0ms)
[ivy:retrieve] :: resolution report :: resolve 140ms :: artifacts dl 16ms
	---------------------------------------------------------------------
	|                  |            modules            ||   artifacts   |
	|       conf       | number| search|dwnlded|evicted|| number|dwnlded|
	---------------------------------------------------------------------
	|      default     |   2   |   1   |   1   |   0   ||   2   |   1   |
	---------------------------------------------------------------------
[ivy:retrieve] :: retrieving :: org.apache#depender
[ivy:retrieve] 	confs: [default]
[ivy:retrieve] 	2 artifacts copied, 0 already retrieved (167kB/16ms)

compile:
    [mkdir] Created dir: /ivy/dependence/depender/build/classes
    [javac] Compiling 1 source file to /ivy/dependence/depender/build/classes

run:
     [java] you are using version 1 of class standalone.Main
     [java] standard message : i am depending.Main and standalone.Main will do the job for me
     [java]     [standalone.Main] capitalizing string "i am depending.Main and standalone.Main will do the job for me" using org.apache.commons.lang.WordUtils
     [java] capitalized message : I Am Depending.main And Standalone.main Will Do The Job For Me

BUILD SUCCESSFUL
Total time: 1 second
What we see here:
  • the project depends on 2 libraries (2 artifacts)
  • one of the libraries was in the cache because there was only 1 download (1 downloaded)
  • Ivy retrieved version 1 of the project "dependee". The call to standalone.Main.getVersion() has returned 1. If you look in the depender/lib directory, you should see dependee-1.jar which is the version 1 artifact of the project "dependee"
  • the call to standalone.Main.capitalizeWords(str) succeed, which means that the required library was in the classpath. If you look at the lib directory, you will see that the library commons-lang-2.0.jar was also retrieved. This library was declared as a dependency of the "dependee" project, so Ivy retrieves it (transitively) along with the dependee artifact.

step 5: new version of dependee project

Like we did before in step 3, publish the dependee project again. This will result in a new version of the project being published. 
[ivy@apache:/ivy/dependence/dependee]$ ant publish
Buildfile: /ivy/dependence/dependee/build.xml

resolve:
[ivy:retrieve] :: Apache Ivy 2.3.0 - 20130110142753 :: http://ant.apache.org/ivy/ ::
[ivy:retrieve] :: loading settings :: file = /ivy/dependence/settings/ivysettings.xml
[ivy:retrieve] :: resolving dependencies :: org.apache#dependee;working@apache
[ivy:retrieve] 	confs: [default]
[ivy:retrieve] 	found commons-lang#commons-lang;2.0 in libraries
[ivy:retrieve] :: resolution report :: resolve 62ms :: artifacts dl 16ms
	---------------------------------------------------------------------
	|                  |            modules            ||   artifacts   |
	|       conf       | number| search|dwnlded|evicted|| number|dwnlded|
	---------------------------------------------------------------------
	|      default     |   1   |   0   |   0   |   0   ||   1   |   0   |
	---------------------------------------------------------------------
[ivy:retrieve] :: retrieving :: org.apache#dependee
[ivy:retrieve] 	confs: [default]
[ivy:retrieve] 	0 artifacts copied, 1 already retrieved (0kB/0ms)

compile:

jar:
[propertyfile] Updating property file: /ivy/dependence/dependee/build/classes/version.properties
      [jar] Building jar: /ivy/dependence/dependee/build/dependee.jar

publish:
   [delete] Deleting: /ivy/dependence/dependee/build/ivy.xml
[ivy:publish] :: delivering :: org.apache#dependee;working@apache :: 2 :: release :: Thu Jan 10 14:34:40 CET 2013
[ivy:publish] 	delivering ivy file to /ivy/dependence/dependee/build/ivy.xml
[ivy:publish] :: publishing :: org.apache#dependee
[ivy:publish] 	published dependee to /ivy/dependence/settings/repository/dependee-2.jar
[ivy:publish] 	published ivy to /ivy/dependence/settings/repository/dependee-2.xml
     [echo] project dependee released with version 2

BUILD SUCCESSFUL
Total time: 1 second
Now if you look in your repository folder, you will find 2 versions of the dependee project.
Let's look at it: 
I:\dependee>dir ..\settings\repository /w

[.]                [..]               dependee-1.jar   dependee-1.xml   dependee-2.jar   dependee-2.xml

I:\dependee>
OK, now our repository contains two versions of the project dependee, so other projects can refer to either version.

step 6: get the new version in depender project

What should we expect if we run the depender project again? It should:
  • retrieve version 2 as the latest.integration version of the dependee project
  • display version 2 of dependee project
Let's try it!! 
[ivy@apache:/ivy/dependence/depender]$ ant 
Buildfile: /ivy/dependence/depender/build.xml

clean:

resolve:
[ivy:retrieve] :: Apache Ivy 2.3.0 - 20130110142753 :: http://ant.apache.org/ivy/ ::
[ivy:retrieve] :: loading settings :: file = /ivy/dependence/settings/ivysettings.xml
[ivy:retrieve] :: resolving dependencies :: org.apache#depender;working@apache
[ivy:retrieve] 	confs: [default]
[ivy:retrieve] 	found org.apache#dependee;2 in projects
[ivy:retrieve] 	[2] org.apache#dependee;latest.integration
[ivy:retrieve] 	found commons-lang#commons-lang;2.0 in libraries
[ivy:retrieve] downloading /ivy/dependence/settings/repository/dependee-2.jar ...
[ivy:retrieve] .. (1kB)
[ivy:retrieve] .. (0kB)
[ivy:retrieve] 	[SUCCESSFUL ] org.apache#dependee;2!dependee.jar (0ms)
[ivy:retrieve] :: resolution report :: resolve 140ms :: artifacts dl 0ms
	---------------------------------------------------------------------
	|                  |            modules            ||   artifacts   |
	|       conf       | number| search|dwnlded|evicted|| number|dwnlded|
	---------------------------------------------------------------------
	|      default     |   2   |   1   |   1   |   0   ||   2   |   1   |
	---------------------------------------------------------------------
[ivy:retrieve] :: retrieving :: org.apache#depender
[ivy:retrieve] 	confs: [default]
[ivy:retrieve] 	2 artifacts copied, 0 already retrieved (167kB/16ms)

compile:
    [mkdir] Created dir: /ivy/dependence/depender/build/classes
    [javac] Compiling 1 source file to /ivy/dependence/depender/build/classes

run:
     [java] you are using version 2 of class standalone.Main
     [java] standard message : i am depending.Main and standalone.Main will do the job for me
     [java]     [standalone.Main] capitalizing string "i am depending.Main and standalone.Main will do the job for me" using org.apache.commons.lang.WordUtils
     [java] capitalized message : I Am Depending.main And Standalone.main Will Do The Job For Me

BUILD SUCCESSFUL
Total time: 1 second
OK, we got what we expected as the run target shows that we are using version 2 of the main class of the dependee project. If we take a look at the resolve target results, we see that one artifact has been downloaded to the ivy cache. In fact, this file is the same version 2 of the dependee project that is in the repository, but now all future retrievals will pull it from your ivy-cache directory.