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From conflue...@apache.org
Subject [CONF] Apache Tuscany Docs 2.x > SCA Java Development Guide
Date Wed, 02 Jun 2010 23:14:00 GMT
Space: Apache Tuscany Docs 2.x (http://cwiki.apache.org/confluence/display/TUSCANYxDOCx2x)
Page: SCA Java Development Guide (http://cwiki.apache.org/confluence/display/TUSCANYxDOCx2x/SCA+Java+Development+Guide)

Edited by Luciano Resende:
This document is the development guideline for SCA Java 2.x project.

* [General Guide|#General Guide]
* [Getting Source code|#Getting Source]
* [Setting up your development environment|#Setup]
* [Importing SCA modules into your Development IDE|#IDE]
* [Coding Guidelines|#Coding Guidelines]
* [Testing|#Testing]
* [Client Applications|#Client Applications]
* [Maven Build Structure|#Maven Build Structure]
* *Development Hints*
** [Generating Eclipse WTP Web Projects for Webapp samples|#Webapp in Eclipse]
** [Generating Dependencies for Ant in Samples|#Ant]

h3.OSGi Overview and Approach

[OSGI & Tuscany|http://people.apache.org/~lresende/presentations/felix%20goes%20to%20tuscany.pdf]

h3. {anchor:General Guide} General Guide

Welcome to the Tuscany SCA Java subproject project. We look forward to your participation
and try to help you get on board. Feel free to ask your questions on the mailing list.

Here are some general guidelines we use in this project.
* Java SCA sub-project aims to provide enterprise-grade service infrastructure based on SCA.
* Tuscany SCA is not just a reference implementation. We encourage innovation based on the
tenets of SCA. A lot of work we do provides feedback to the specifications.
* The Java SCA infrastructure should provide flexibility and choice. It should not dictate
programming models but support many.
* The Java SCA infrastructure is very modularized and is designed to be highly extensible
so users can customize it to fit their needs.

h3. {anchor:Prerequisites} Prerequisites

Java SCA requires the following:
* [J2SE 1.6.0+)|http://java.sun.com/javase/downloads/index.jsp]
* [Apache Maven (2.2.1+)|http://maven.apache.org/]
* [Subversion (1.6+)|http://subversion.tigris.org/] or [TortoiseSVN (1.6.x+)|http://tortoisesvn.tigris.org/]
* [Eclipse PDE (Ganymede ) |http://www.eclipse.org/downloads]

h4. Checking out code from Subversion

Use the command as follows:
svn checkout https://svn.apache.org/repos/asf/tuscany/sca-java-2.x/trunk/

h3. {anchor:Setup} Setting up your Development Environment

h4. top-down build (recommended approach)

Check out all of the java source code.
svn checkout https://svn.apache.org/repos/asf/tuscany/sca-java-2.x/trunk/
Building the SCA source code :
cd trunk
mvn -fae clean install
It should work even if you start with an empty Maven local repository, and it should always
work, however when you are building for Tuscany for the first time there are a lot of dependencies
which must be downloaded so the first build can take a long time and it may fail with problems
retrieving the dependencies.

(on) There can be occasional problems downloading artifacts from remote Maven repositories
so if mvn fails with network related sounding messages sometimes just trying again can fix
the problem.

(on) The trunk code sometimes has SNAPSHOT dependencies which can get out of date in your
local repository so if you see odd build failures try updating the SNAPSHOT jars by using
the "-U" parameter in the mvn command.

(on) Once you have done a top-down build, and your local maven repository is populated, you
can start using the maven off line option to speed up the build process by using the "-o"
parameter in the mvn command.

 The SCA build consumes a good amount of memory, in case you are seeing issues during the
build, set a MAVEN_OPTS environment variable to allocate more memory for the build process.

 Windows : SET MAVEN_OPTS="-Xmx512m -XX:MaxPermSize=384m"
 Unix    : export MAVEN_OPTS="-Xmx512m -XX:MaxPermSize=384m"

   If you are using MAC OS, please see 'Special instructions for MAC OS users' section below

h3. {anchor:IDE}Importing SCA modules into your Development IDE

h4. Using Eclipse

If this is the first time you are using your workspace with maven m2 local repository, you
will need to tell your Eclipse workspace the location of the directory, and you can do this
with the following command :
mvn -Declipse.workspace=[path-to-eclipse-workspace] eclipse:add-maven-repo
In order to generate the necessary project files to import the SCA modules to Eclipse, you
can use the maven eclipse plugin

mvn eclipse:eclipse

Now launch your Eclipse IDE, select File->Import->Existing projects into Workplace,
and then import the project from SCA Modules into your Eclipse Workspace.

h4. Using Eclipse PDE

To help with development in an OSGi environment Tuscany also has a build profile to setup
the Eclipse Plugin Development Environment:
mvn -fae -Peclipse

Now set the "Target Platform" in your Eclipse IDE by following the steps below :

* Inside eclipse, select File->Open File" and open "distribution/all/target/features/tuscany.target"
** click "Set as target platform" on the upper-right side of the overview window that opened

Then as when using eclipse:eclipse launch your Eclipse IDE, select File->Import->Existing
projects into Workplace, and then import the project from SCA Modules into your Eclipse Workspace.

There are also some Tuscany Eclipse code templates available:
[Eclipse Style Formatter | https://svn.apache.org/repos/asf/tuscany/java/etc/tuscany-eclipse-codestyle.xml
[Eclipse Templates | https://svn.apache.org/repos/asf/tuscany/java/etc/tuscany-eclipse-codetemplates.xml

h4. {anchor:Eclipse Build Troubleshooting} Eclipse Build Troubleshooting

Sometimes a Maven build will work from the command line, yet the same component will not build
in the Eclipse environment. Of course, developers try to prevent this from happening, but
it does happen and makes for a valid Jira. In the meantime, here are some steps that might
help correct build issues in the Eclipse environment:

* *Missing classpath variables* - Sometimes Java build classpath variables are incorrect or
missing, for instance "Unbound classpath variable: 'M2_REPO/com/sun/xml/bind/jaxb-impl/2.1.9/jaxb-impl-2.1.9.jar'".
Add the classpath variable 'M2_REPOS' to your workspace. Window > Preferences > Java
> Build Path > Classpath variables. Create variables for any missing variables and point
them to the appropriate place in your file system. Do a complete rebuild.

* *Missing projects* - Sometimes developers add or remove project dependencies. These show
up with error message "The project cannot be built until build path errors are resolved".
This is often a sign that your Eclipse workspace is out of sync with your local repository
or the svn repository. The full remedy is to refresh your local repos (svn update), rebuild
your local repos (mvn clean install -U), regenerate Eclipse projects (mvn -Declipse), reimport
projects in Eclipse, and clean/rebuild your projects. You may be able to do less than this
full refresh with simple changes, but the full refresh is often needed for major changes.

* *Project won't build* - Sometimes a particular project will not build despite repeated efforts.
Consider if this project is necessary to the task at hand. You may be able to delete the problematic
Eclipse project and continue with other work.

h3. {anchor:MacOS} Special instructions for MAC OS users

Some plugins used in the Tuscany build requires a explicit dependency on some classes from
JDK tools.jar, which is in a different place in the MAC OS environment. 

We have created duplicate profiles in Tuscany to accommodate the most used user tasks

* Running a build : there is a default profile for the mac environment properly configuring
the tools.jar property
   mvn clean install

* Creating Eclipse IDE project files : there is a "eclipse-mac" profile
   mvn -Peclipse-mac

h4. Update your maven settings.xml (%user_home%/.m2/settings.xml)

Updating your settings.xml with proper property configuration will make all profiles work
in a MAC OS environment.




h3. {anchor:Coding Guidelines} Coding Guidelines

There are a few simple guidelines when developing for JAVA SCA:
* The basic coding style used is the described at [Sun Java coding standards|http://java.sun.com/docs/codeconv/]
but the main thing is to be consistent with the existing code you're updating, so for example,
if you're updating a method that uses the braces on the same line style don't add code with
the hanging braces style.

* Always include the Apache License Headers on all files (both source code files and resource
files such as xml documents)

* Include a descriptive log message for checkins, for example "fixed such and such problem".

While Tuscany does not yet have an official style or template, here are some templates that
folks have been using and have been checked into the build which are stored at [https://svn.apache.org/repos/asf/tuscany/java/etc/]

h4. Naming conventions to increase consistency

*Folder Names:* Please use all lowercases and dashes in folder names (like in the jar names)
- Maven artifact id = tuscany-<folder name>

*Package names:* Package names within modules should include the module name so that source
code can be located in the source tree easily. So, for example, java/sca/module/implementation-java
would be in package structure org.apache.tuscany.implementation.java.\*

h3. {anchor:Testing} Testing

Tuscany uses plain junit test cases to perform unit and integration testing, below is an example
that can also be used as a template for writing new test cases; it demonstrates how to bootstrap
the Tuscany SCA runtime in your test case, and because they are based on junit, you can run
it from your IDE of choice or from Maven.

Note that we are using JUnit 4.2 code style in OSGI development stream

 * Description of your test case and necessary details you find necessary
@Scope("COMPOSITE") @EagerInit
public class CalculatorTestCase {

    private static CalculatorService calculatorService;
    private static NodeLauncher launcher;
    private static Node node;

    public void setCalculatorService(CalculatorService calculatorService) {
        CalculatorTestCase.calculatorService = calculatorService;
    public static void setUpBeforeClass() throws Exception {
        launcher = NodeLauncher.newInstance();
        String location = ContributionLocationHelper.getContributionLocation(CalculatorClient.class);
        node = launcher.createNode("Calculator.composite", new Contribution("test", location));
        System.out.println("SCA Node API ClassLoader: " + node.getClass().getClassLoader());

    public static void tearDownAfterClass() throws Exception {
        if (node != null) {
        if (launcher != null) {

    public void testCalculator() throws Exception {
        // Calculate
        assertEquals(calculatorService.add(3, 2), 5.0);
        assertEquals(calculatorService.subtract(3, 2), 1.0);
        assertEquals(calculatorService.multiply(3, 2), 6.0);
        assertEquals(calculatorService.divide(3, 2), 1.5);
(on) Note that we use surefire maven plugin to run the unit and integration tests, and in
most cases, they are configured to match a \**/*TestCase.java file name pattern. Because of
this, if your test case has a different file name pattern, you might execute it from your
IDE of choice, but the maven build won't execute the test.

h3. {anchor:Client Applications} Client Applications as SCA Components

Below is how you can build client applications as an SCA component.

@Scope("COMPOSITE") @EagerInit
public class CalculatorClient {
    private CalculatorService calculatorService;

    public void setCalculatorService(CalculatorService calculatorService) {
        this.calculatorService = calculatorService;
    public void calculate() {

        // Calculate
        System.out.println("SCA API ClassLoader: " + print(Reference.class.getClassLoader()));
        System.out.println("3 + 2=" + calculatorService.add(3, 2));
        System.out.println("3 - 2=" + calculatorService.subtract(3, 2));
        System.out.println("3 * 2=" + calculatorService.multiply(3, 2));
        System.out.println("3 / 2=" + calculatorService.divide(3, 2));
    private static String print(ClassLoader cl) {
        StringBuffer buf = new StringBuffer();
        for (; cl != null;) {
            buf.append(' ');
            cl = cl.getParent();
        return buf.toString();


h3. {anchor:Maven Build Structure} Maven Build Structure

_We use the term Module to refer to the leaf of maven tree._
* sca/pom.xml's parent will be pom/parent/pom.xml
* Other poms will use the pom from the parent folder as parent pom
* Group id: org.apache.tuscany.sca
* Version of our modules will be specified once in java/sca/pom.xml, child poms don't need
specify a version as they get it from their parent
* pom names begin Apache Tuscany SCA
* Eclipse projects are generated for all built modules using mvn eclipse:eclipse

h4. Adding a new module and not ready to integrate?

'work-in-progress' modules can be worked on in the same source tree and yet not break the
top-down build. You can do this by not listing your module(s) in java/sca/modules/pom.xml.

h2. Development Hints

h3. {anchor:Webapp in Eclipse} Generating Eclipse WTP Web Projects for Webapp samples

If you're using Eclipse WTP and want to get WTP Web Projects generated
for our Webapp samples you can simply pass a \-Dwtpversion=1.5 option to
the usual mvn eclipse:eclipse command, like this:
mvn \-Dwtpversion=1.5 \-Peclipse eclipse:eclipse

The magic \-Dwtpversion=1.5 option will add the WTP Web project nature to
all the Eclipse projects with <packaging>war</packaging> in their Maven
pom.xml. You'll then be able to add these projects to a WTP Tomcat or
Geronimo Server configuration, to publish and run them straight from
your Eclipse workspace.

h3:{anchor:Ant} Generating Dependencies for Ant in Samples

Figuring out the package dependency to include in Ant build.xml can be a pain. Here is a quick
script which works in Linux environment for war files.
jar tvf sample-feed-aggregator-webapp.war | grep .jar | awk '{ printf "%s\n", $8 }' |
   sed -e "s/WEB-INF\/lib\///" | awk '{ printf "<include name=\"%s\"/>\n", $1 }' | grep
-v tuscany

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