SCA Java 2.x Development Guide : Apache Tuscany

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How to get involved in development of Java SCA?

+

This document is the development guideline for SCA Java project.

+

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

OSGi Overview and Approach

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OSGI & Tuscany

+ +

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.

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Prerequisites

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Java SCA requires the following:

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+ + +

Checking out code from Subversion

+ +

Use the command as follows:

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+svn checkout https://svn.apache.org/repos/asf/tuscany/java/sca
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+

+ +

Setting up your Development Environment

+ +

top-down build (recommended approach)

+ +

Check out all of the java source code.

+

+svn checkout https://svn.apache.org/repos/asf/tuscany/java/sca
+

+

Building the SCA source code :

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+mvn -Psetup clean install
+mvn -fae clean install
+cd  distribution
+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.

+ +

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.

+ +

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.

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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.

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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
+ Unix : export MAVEN_OPTS=-Xmx512m

+ +

Importing SCA modules into your Development IDE

+ + +

Using Eclipse

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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 :

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+mvn -Declipse.workspace=[path-to-eclipse-workspace] eclipse:add-maven-repo
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In order to generate the necessary project files to import the SCA modules to Eclipse, you can use the maven eclipse plugin

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

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Now, launch your Eclipse IDE, select File->Import->Existing projects into Workplace, and then import the "PDE Target" project (from distribution/pdetarget) into your Eclipse Workspace.

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Import distribution/pdetarget
Inside eclipse, open tuscany-distribution-pdetarget project +
- open target/tuscany-distribution-pdetarget.target
- click "Set as target platform" on the upper-right side of the overview window that opened
+

+ + +

There are some Tuscany Eclipse code templates available:
+Eclipse Style Formatter
+Eclipse Templates

+ +

Coding Guidelines

+ +

There are a few simple guidelines when developing for JAVA SCA:

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The basic coding style used is the described at Sun Java coding standards 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.

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

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

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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/

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Naming conventions to increase consistency

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Folder Names: Please use all lowercases and dashes in folder names (like in the jar names)

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Maven artifact id = tuscany-<folder name>

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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.*

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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;
+
+    @Reference
+    public void setCalculatorService(CalculatorService calculatorService) {
+        CalculatorTestCase.calculatorService = calculatorService;
+    }
+    
+    
+    @BeforeClass
+    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());
+        node.start();
+    }
+
+    @AfterClass
+    public static void tearDownAfterClass() throws Exception {
+        if (node != null) {
+            node.stop();
+            node.destroy();
+        }
+        if (launcher != null) {
+            launcher.destroy();
+        }
+    }
+
+    @Test
+    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);
+    }
+}
+

+

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.

+ +

Client Applications as SCA Components

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

+ +

+

+@Scope("COMPOSITE") @EagerInit
+public class CalculatorClient {
+    
+    private CalculatorService calculatorService;
+
+    @Reference
+    public void setCalculatorService(CalculatorService calculatorService) {
+        this.calculatorService = calculatorService;
+    }
+    
+    @Init
+    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.toString());
+            buf.append(' ');
+            cl = cl.getParent();
+        }
+        return buf.toString();
+    }
+
+}
+

+

+ +

Maven Build Structure

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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 -Peclipse eclipse:eclipse

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Adding a new module and not ready to integrate?

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'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.

+ +

Development Hints

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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: 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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