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Maven Kicking the tyres without changing your project structure

Version 22.1 by Lachlan Deck on 2008/06/24 00:39
Warning: For security reasons, the document is displayed in restricted mode as it is not the current version. There may be differences and errors due to this.

So you're interested in kicking the maven tyres, so to speak, or just want to see what it's all about. The following provides hints on how to try maven with your current WebObjects projects, if say you're using the standard WOLips ant builds, without having to adopt a different file structure. Whilst this is not the recommended approach for the long term it allows you to try things out side-by-side with your current build system.

Information
Recommended Homework (or pre-requisites)

It's _really_ worth doing your homework on maven in order to understand it. The place to start is Learning Maven found at [http://maven.apache.org]. Various guides are also found at [http://maven.apache.org/guides/].

At the very least you want to have read through, and understood, the [Getting Started Tutorial|http://maven.apache.org/guides/getting-started/index.html].

The maven user mailing list is also recommended for getting help. It's quite active and, as you find for the WebObjects mailing lists, is an invaluable resource. See [Getting Help|http://maven.apache.org/users/getting-help.html].

Success

Hang in there

This particular guide might look long but some of the xml is duplicated a few times to show differing examples.

What's the aim

This might be stating the obvious, but an OO developer will, in the course of time (or is supposed to anyway), build up various encapsulated, reusable, libraries or frameworks that can be tapped into for differing projects. So let's assume we have multiple frameworks and applications in our build. Each of these has some common ground, such as their dependencies on certain WebObjects frameworks, or the file layout, and of course they each may have something distinctive about them.

The layout of the frameworks and applications might look like this:

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Our aim is twofold:

  1. put as much configuration as possible that's shared between all frameworks, for example, into /frameworks/pom.xml so we only have to define it once. The configuration is inherited by a child pom.
  2. Be able to issue a single command that will package each and every framework and application.

Key Concepts

Typical things that make up a pom are as follows. (Note: only pom identification is mandatory. All the others have defaults.)

  1. pom identification (who am I?)
    The base triplet used to identify an artifact (i.e., product)

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  1. pom packaging (i.e., what are we building?)
    The default value for the packaging element is JAR if not specified. For the purposes of this exercise, we'll use JAR for the frameworks and woapplication for the applications, which requires the woproject maven plugin (TODO revisit this scenario with the apple maven plugin)

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  1. pom parent identification (who do I belong to?)

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  1. modules (a.k.a kids; who belongs to me?)

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  1. dependencies (what do I need?)

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  1. build sources/resources (what do I have?)
  2. properties and filtering resources (variable definitions)
  3. dependency/plugin management (shared configuration and versioning)
  4. repositories (where to find dependencies and plugins)

Of course, with the plethora of plugins available for maven, this is only the tip of the iceberg. However, these main concepts will suffice for now.

Alternate File System Layout Concepts

As you would (i.e., should) have read by now, Maven has what it calls standards. One such standard is the standard directory layout. One of the advantages of following the standards is that you get something for free: you have less to configure (or even almost nothing) in order to build a jar, for example, from your sources and resources. When that's not possible, options are available that allow you to subvert these standards or provide extra resouces.

Success

Mavan Model Reference Doco

To see what built-in options are available for maven see [Maven Model|http://maven.apache.org/ref/2.0.9/maven-model/maven.html].

The following roughly resembles the current WebObjects WOLips produced project layout (a.k.a Fluffy Bunny layout).

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Assuming your building a framework, for example, the following is an extract from the relevant pom.xml. It specifies where to find your java source files and resources. Notice we've also defined the target path for each resource. (See the Maven Model#classresource for a definition of targetPath)

pom.xml

<...>
 <build>
   <sourceDirectory>Sources</sourceDirectory>
   <testSourceDirectory>Tests</testSourceDirectory>
   <resources>
     <resource>
       <targetPath>Resources</targetPath>
       <filtering>false</filtering>
       <directory>Components</directory>
     </resource>
     <resource>
       <targetPath>Resources</targetPath>
       <filtering>false</filtering>
       <directory>Resources</directory>
     </resource>
     <resource>
       <targetPath>WebServerResources</targetPath>
       <filtering>false</filtering>
       <directory>WebServerResources</directory>
     </resource>
   </resources>
   <...>
 </build>
<...>

So, concentrating on our frameworks alone for the moment, assuming all of your frameworks share the above project layout the above can happily go into your /frameworks/pom.xml file and as such be shared by all sub-modules (i.e., frameworks).

Project Dependencies Concepts

Most projects, of course, have dependencies on other libraries or frameworks. See the Maven Getting Started#HowdoIuseexternaldependencies.

The following shows the mixture of third party dependencies and custom framework dependencies. Notice that the scope element determines the life cycle phase each dependency is relevant for. See Maven Model#classdependency for specific definitions.

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Repositories

So far we have assumed that maven just knows where to find third party libraries. There is the default local repository (e.g., /.m2/repository) and a remote one at ibiblio.org or a mirror of the same. See http://maven.apache.org/guides/introduction/introduction-to-repositories.html.

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Note: A remote repository is not guaranteed to keep older versions of libraries, for example, indefinitely. It's recommended that you set up one for your intranet which stores what you need for longevity. See both the above intro to repositories and http://www.theserverside.com/tt/articles/article.tss?l=SettingUpMavenRepository.

Packaging Frameworks as Jars

Here's the definition for /frameworks/pom.xml.

/frameworks/pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
    http://maven.apache.org/xsd/maven-4.0.0.xsd">

   <modelVersion>4.0.0</modelVersion>
   
   <!-- parent artifact -->
   <parent>
       <artifactId>mywostuff</artifactId>
       <groupId>com</groupId>
       <version>1.0-SNAPSHOT</version>
   </parent>

   <!-- artifact identity -->
   <artifactId>frameworks</artifactId>
   <groupId>com.mywostuff</groupId>
   <packaging>pom</packaging>
   
   <!-- framework relevant properties -->
   <properties>
       <!-- NS related properties fills in Info.plist etc-->
       <CFBundleDevelopmentRegion>English</CFBundleDevelopmentRegion>
       <CFBundleGetInfoString></CFBundleGetInfoString>
       <CFBundlePackageType>FMWK</CFBundlePackageType>
       <CFBundleIconFile>WOAfile.icns</CFBundleIconFile>
       <CFBundleInfoDictionaryVersion>6.0</CFBundleInfoDictionaryVersion>
       <CFBundleVersion>5.3.1</CFBundleVersion>
       <Has_WOComponents>true</Has_WOComponents>
       <NSPrincipalClass>${mainclass}</NSPrincipalClass>
       <NSResourcesBundlePath></NSResourcesBundlePath>
   </properties>

   <!-- modules -->
   <modules>
       <module>CustomExtensions</module>
       <module>CustomBusinessLogic</module>
   </modules>

   <!-- specific dependencies (for modules) -->
   <dependencies>
       <dependency>
           <artifactId>ERExtensions</artifactId>
           <groupId>${wonder.common.groupId}</groupId>
       </dependency>
       <dependency>
           <artifactId>JavaWOExtensions</artifactId>
           <groupId>${wonder.common.groupId}</groupId>
       </dependency>
       <dependency>
           <artifactId>JavaFoundation</artifactId>
           <groupId>${webobjects.groupId}</groupId>
       </dependency>
       <dependency>
           <artifactId>JavaJDBCAdaptor</artifactId>
           <groupId>${webobjects.groupId}</groupId>
       </dependency>
       <dependency>
           <artifactId>JavaWebObjects</artifactId>
           <groupId>${webobjects.groupId}</groupId>
       </dependency>
       <dependency>
           <artifactId>JavaEOControl</artifactId>
           <groupId>${webobjects.groupId}</groupId>
       </dependency>
       <dependency>
           <artifactId>JavaEOAccess</artifactId>
           <groupId>${webobjects.groupId}</groupId>
       </dependency>
       <dependency>
           <artifactId>JavaWebObjects</artifactId>
           <groupId>${webobjects.groupId}</groupId>
       </dependency>
       <dependency>
           <artifactId>JavaXML</artifactId>
           <groupId>${webobjects.groupId}</groupId>
       </dependency>
   </dependencies>


   <!-- build config (for modules) -->
   <build>
       <sourceDirectory>src</sourceDirectory>
       <testSourceDirectory>tests</testSourceDirectory>
       <resources>
           <!-- relative dir for Info.plist -->
           <resource>
               <targetPath>Resources</targetPath>
               <filtering>true</filtering>
               <directory>../src/main/resources</directory>
           </resource>
           <resource>
               <targetPath>Resources</targetPath>
               <filtering>false</filtering>
               <directory>Components</directory>
           </resource>
           <resource>
               <targetPath>Resources</targetPath>
               <filtering>false</filtering>
               <directory>Resources</directory>
           </resource>
           <resource>
               <targetPath>WebServerResources</targetPath>
               <filtering>false</filtering>
               <directory>WebServerResources</directory>
           </resource>
       </resources>
       <plugins>
           <plugin>
               <groupId>org.apache.maven.plugins</groupId>
               <artifactId>maven-compiler-plugin</artifactId>
               <configuration>
                   <source>${java.target}</source>
                   <target>${java.target}</target>
               </configuration>
           </plugin>
       </plugins>
   </build>
</project>

and CustomExtensions which has no further dependencies

/frameworks/CustomBusinessLogic/pom.xml

<?xml version="1.0"?>
<project>
   <!-- parent artifact -->
   <parent>
       <artifactId>frameworks</artifactId>
       <groupId>com.mywostuff</groupId>
       <version>1.0-SNAPSHOT</version>
   </parent>

   <!-- artifact identity -->
   <artifactId>CustomBusinessLogic</artifactId>
   <groupId>com.mywostuff.frameworks</groupId>
</project>

and CustomBusinessLogic (which has a further dependency on CustomExtensions)

/frameworks/CustomBusinessLogic/pom.xml

<?xml version="1.0"?>
<project>
   <!-- parent artifact -->
   <parent>
       <artifactId>frameworks</artifactId>
       <groupId>com.mywostuff</groupId>
       <version>1.0-SNAPSHOT</version>
   </parent>

   <!-- artifact identity -->
   <artifactId>CustomBusinessLogic</artifactId>
   <groupId>com.mywostuff.frameworks</groupId>
   
   <!-- specific dependencies -->
   <dependencies>
       <dependency>
           <artifactId>CustomExtensions</artifactId>
           <groupId>${pom.groupId}</groupId>
       </dependency>
   </dependencies>
</project>

Packaging Applications

details to come...

Packaging Applications as True WAR

You can find steps to package WO Applications as True WAR here.

more details to come...

Project Inheritance

details to come...

Eclipse Integration

details to come...

Putting It All Together

details to come...