Modified: zest/site/content/java/develop/website.html URL: http://svn.apache.org/viewvc/zest/site/content/java/develop/website.html?rev=1689843&r1=1689842&r2=1689843&view=diff ============================================================================== --- zest/site/content/java/develop/website.html (original) +++ zest/site/content/java/develop/website.html Wed Jul 8 11:08:41 2015 @@ -48,16 +48,18 @@ <script type="text/javascript" src="js/tablestyler.js"></script> -</head><body><div xml:lang="en" class="article" lang="en"><div class="titlepage"><hr /></div><div class="toc"><p><strong>Table of Contents</strong></p><dl><dt><span class="section"><a href="#home">1. Qi4j</a></span></dt><dd><dl><dt><span class="section"><a href="#_what_is_qi4j">1.1. What is Qi4jâ¢?</a></span></dt></dl></dd><dt><span class="section"><a href="#intro">2. Introduction</a></span></dt><dd><dl><dt><span class="section"><a href="#highlights">2.1. Highligts</a></span></dt><dt><span class="section"><a href="#introduction-background">2.2. Background</a></span></dt><dt><span class="section"><a href="#what-is-cop">2.3. What is COP?</a></span></dt><dt><span class="section"><a href="#what-s-an-object-anyway">2.4. Whatâs an Object anyway?</a></span></dt><dt><span class="section"><a href="#state-modeling">2.5. Qi4j and state modeling</a></span></dt><dt><span class="section"><a href="#related">2.6. Related publications & projects</a></span></dt></dl></dd><dt><span class= "section"><a href="#tutorials">3. Tutorials</a></span></dt><dd><dl><dt><span class="section"><a href="#_overview">3.1. Overview</a></span></dt><dt><span class="section"><a href="#two-minutes-intro">3.2. Qi4j in 2 minutes</a></span></dt><dt><span class="section"><a href="#ten-minutes-intro">3.3. Qi4j in 10 minutes</a></span></dt><dt><span class="section"><a href="#thirty-minutes-intro">3.4. Qi4j in 30 minutes</a></span></dt><dt><span class="section"><a href="#two-hours-intro">3.5. Qi4j in 2 hours</a></span></dt><dt><span class="section"><a href="#howto-depend-on-qi4j">3.6. Depend on Qi4j in your build</a></span></dt><dt><span class="section"><a href="#howto-assemble-application">3.7. Assemble an Application</a></span></dt><dt><span class="section"><a href="#tut-composites">3.8. Transient Composites Tutorial</a></span></dt><dt><span class="section"><a href="#tut-services">3.9. Services Composites Tutorial</a></span></dt><dt><span class="section"><a href="#howto-contextual-fragments">3 .10. Use contextual fragments</a></span></dt><dt><span class="section"><a href="#howto-leverage-properties">3.11. Leverage Properties</a></span></dt><dt><span class="section"><a href="#howto-create-constraint">3.12. Create a Constraint</a></span></dt><dt><span class="section"><a href="#howto-create-concern">3.13. Create a Concern</a></span></dt><dt><span class="section"><a href="#howto-create-sideeffect">3.14. Create a SideEffect</a></span></dt><dt><span class="section"><a href="#howto-create-entity">3.15. Create an Entity</a></span></dt><dt><span class="section"><a href="#howto-configure-service">3.16. Configure a Service</a></span></dt><dt><span class="section"><a href="#howto-invocation-annotation">3.17. Use @Invocation</a></span></dt><dt><span class="section"><a href="#howto-use-io">3.18. Use I/O API</a></span></dt><dt><span class="section"><a href="#build-system">3.19. Build System</a></span></dt><dt><span class="section"><a href="#community-docs">3.20. Writing Qi4j Documentati on</a></span></dt></dl></dd><dt><span class="section"><a href="#javadocs">4. Javadoc</a></span></dt><dd><dl><dt><span class="section"><a href="#_javadocs">4.1. JavaDocs</a></span></dt></dl></dd><dt><span class="section"><a href="#samples">5. Samples</a></span></dt><dd><dl><dt><span class="section"><a href="#_overview_2">5.1. Overview</a></span></dt><dt><span class="section"><a href="#sample-dci">5.2. DCI Sample</a></span></dt><dt><span class="section"><a href="#sample-dci-cargo">5.3. DCI Cargo Sample</a></span></dt><dt><span class="section"><a href="#sample-forum">5.4. Forum Sample</a></span></dt><dt><span class="section"><a href="#sample-car-rental">5.5. Car Rental Sample</a></span></dt><dt><span class="section"><a href="#sample-sql-support">5.6. SQL Support Sample</a></span></dt><dt><span class="section"><a href="#sample-swing">5.7. Swing Bindings Sample</a></span></dt></dl></dd><dt><span class="section"><a href="#core">6. Core</a></span></dt><dd><dl><dt><span class="section"><a h ref="#_overview_3">6.1. Overview</a></span></dt><dt><span class="section"><a href="#core-api">6.2. Core API</a></span></dt><dt><span class="section"><a href="#core-bootstrap-assembly">6.3. Core Bootstrap</a></span></dt><dt><span class="section"><a href="#core-testsupport">6.4. Core Test Support</a></span></dt><dt><span class="section"><a href="#core-functional">6.5. Core Functional API</a></span></dt><dt><span class="section"><a href="#core-io">6.6. Core I/O API</a></span></dt><dt><span class="section"><a href="#core-spi">6.7. Core Extension SPI</a></span></dt><dt><span class="section"><a href="#core-runtime">6.8. Core Runtime</a></span></dt></dl></dd><dt><span class="section"><a href="#libraries">7. Libraries</a></span></dt><dd><dl><dt><span class="section"><a href="#_overview_5">7.1. Overview</a></span></dt><dt><span class="section"><a href="#library-alarm">7.2. Alarms</a></span></dt><dt><span class="section"><a href="#library-circuitbreaker">7.3. Circuit Breaker</a></span></dt><d t><span class="section"><a href="#library-constraints">7.4. Constraints</a></span></dt><dt><span class="section"><a href="#library-conversion">7.5. Conversion</a></span></dt><dt><span class="section"><a href="#library-eventsourcing">7.6. Event Sourcing</a></span></dt><dt><span class="section"><a href="#library-eventsourcing-jdbm">7.7. Event Sourcing - JDBM</a></span></dt><dt><span class="section"><a href="#library-eventsourcing-rest">7.8. Event Sourcing - ReST</a></span></dt><dt><span class="section"><a href="#library-fileconfig">7.9. FileConfig</a></span></dt><dt><span class="section"><a href="#library-http">7.10. HTTP</a></span></dt><dt><span class="section"><a href="#library-invocation-cache">7.11. Invocation Cache</a></span></dt><dt><span class="section"><a href="#library-jmx">7.12. JMX</a></span></dt><dt><span class="section"><a href="#library-locking">7.13. Locking</a></span></dt><dt><span class="section"><a href="#library-logging">7.14. Logging</a></span></dt><dt><span class= "section"><a href="#library-osgi">7.15. OSGi</a></span></dt><dt><span class="section"><a href="#library-rdf">7.16. RDF</a></span></dt><dt><span class="section"><a href="#library-rest-client">7.17. ReST Client</a></span></dt><dt><span class="section"><a href="#library-rest-client-primer">7.18. ReST - HATEOAS Primer</a></span></dt><dt><span class="section"><a href="#library-rest-common">7.19. ReST Common</a></span></dt><dt><span class="section"><a href="#library-rest-server">7.20. ReST Server</a></span></dt><dt><span class="section"><a href="#library-scheduler">7.21. Scheduler</a></span></dt><dt><span class="section"><a href="#library-script-groovy">7.22. Groovy Scripting</a></span></dt><dt><span class="section"><a href="#library-script-javascript">7.23. Javascript Scripting</a></span></dt><dt><span class="section"><a href="#lang-scala">7.24. Scala Support</a></span></dt><dt><span class="section"><a href="#library-servlet">7.25. Servlet</a></span></dt><dt><span class="section"><a href ="#library-shiro">7.26. Shiro Security</a></span></dt><dt><span class="section"><a href="#library-shiro-web">7.27. Shiro Web Security</a></span></dt><dt><span class="section"><a href="#library-spring">7.28. Spring Integration</a></span></dt><dt><span class="section"><a href="#library-sql">7.29. SQL</a></span></dt><dt><span class="section"><a href="#library-uid">7.30. UID</a></span></dt><dt><span class="section"><a href="#library-uowfile">7.31. UoWFile</a></span></dt></dl></dd><dt><span class="section"><a href="#extensions">8. Extensions</a></span></dt><dd><dl><dt><span class="section"><a href="#_overview_7">8.1. Overview</a></span></dt><dt><span class="section"><a href="#extension-vs-orgjson">8.2. org.json ValueSerialization</a></span></dt><dt><span class="section"><a href="#extension-vs-jackson">8.3. Jackson ValueSerialization</a></span></dt><dt><span class="section"><a href="#extension-vs-stax">8.4. StAX ValueSerialization</a></span></dt><dt><span class="section"><a href="#extensi on-cache-ehcache">8.5. Ehcache Cache</a></span></dt><dt><span class="section"><a href="#extension-cache-memcache">8.6. Memcache Cache</a></span></dt><dt><span class="section"><a href="#extension-es-memory">8.7. Memory EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-file">8.8. File EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-hazelcast">8.9. Hazelcast EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-jclouds">8.10. JClouds EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-jdbm">8.11. JDBM EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-leveldb">8.12. LevelDB EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-mongodb">8.13. MongoDB EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-preferences">8.14. Preferences EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-redis">8.15. Redis EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-riak">8.16. Riak EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-sql">8.17. SQL EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-voldemort">8.18. Voldemort EntityStore</a></span></dt><dt><span class="section"><a href="#extension-index-elasticsearch">8.19. ElasticSearch Index/Query</a></span></dt><dt><span class="section"><a href="#extension-index-rdf">8.20. OpenRDF Index/Query</a></span></dt><dt><span class="section"><a href="#extension-index-solr">8.21. Apache Solr Index/Query</a></span></dt><dt><span class="section"><a href="#extension-indexing-sql">8.22. SQL Index/Query</a></span></dt><dt><span class="section"><a href="#extension-metrics-yammer">8.23. Yammer Metrics</a></span></dt><dt><span class="section"><a href="#extension-migration">8.24. Migration</a></span></dt><dt><span class="section"><a href="#extension-reindexer">8.25. Reindexer</a></ span></dt></dl></dd><dt><span class="section"><a href="#tools">9. Tools</a></span></dt><dd><dl><dt><span class="section"><a href="#_overview_8">9.1. Overview</a></span></dt><dt><span class="section"><a href="#tools-envisage">9.2. Envisage</a></span></dt></dl></dd><dt><span class="section"><a href="#glossary">10. Glossary </a></span></dt></dl></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h2 class="title" style="clear: both"><a id="home"></a>1. Qi4j</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#_what_is_qi4j">1.1. What is Qi4jâ¢?</a></span></dt></dl></div><div class="important" style="margin-left: 0; margin-right: 10%;"><table border="0" summary="Important"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Important]" src="images/icons/admon/important.png" /></td><th align="left">Important</th></tr><tr><td align="left" valign="top" ><p>This is the documentation for <span class="strong"><strong>Qi4j >0</strong></span>. Use the version switcher on the left to browse other -versions documentation.</p></td></tr></table></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h3 class="title"><a id="_what_is_qi4j"></a>1.1. What is Qi4jâ¢?</h3></div></div></div><p>The short answer is that Qi4j⢠is a framework for domain centric application development, including evolved concepts -from <a class="ulink" href="http://en.wikipedia.org/wiki/Aspect-oriented_programming"; target="_top">AOP</a>, -<a class="ulink" href="http://en.wikipedia.org/wiki/Dependency_injection"; target="_top">DI</a> and <a class="ulink" href="http://en.wikipedia.org/wiki/Domain-driven_design"; target="_top">DDD</a>.</p><p>Qi4j⢠is an implementation of Composite Oriented Programming, using the standard Java platform, without the use of +</head><body><div xml:lang="en" class="article" lang="en"><div class="titlepage"><hr /></div><div class="toc"><p><strong>Table of Contents</strong></p><dl><dt><span class="section"><a href="#home">1. Zestâ¢</a></span></dt><dd><dl><dt><span class="section"><a href="#_what_is_apache_zest">1.1. What is Apache Zest⢠?</a></span></dt><dt><span class="section"><a href="#_brief_history">1.2. Brief History</a></span></dt></dl></dd><dt><span class="section"><a href="#intro">2. Introduction</a></span></dt><dd><dl><dt><span class="section"><a href="#highlights">2.1. Highligts</a></span></dt><dt><span class="section"><a href="#introduction-background">2.2. Background</a></span></dt><dt><span class="section"><a href="#what-is-cop">2.3. What is COP?</a></span></dt><dt><span class="section"><a href="#what-s-an-object-anyway">2.4. Whatâs an Object anyway?</a></span></dt><dt><span class="section"><a href="#state-modeling">2.5. Zest⢠and state modeling</a></span></dt><dt><span clas s="section"><a href="#related">2.6. Related publications & projects</a></span></dt></dl></dd><dt><span class="section"><a href="#tutorials">3. Tutorials</a></span></dt><dd><dl><dt><span class="section"><a href="#_overview">3.1. Overview</a></span></dt><dt><span class="section"><a href="#two-minutes-intro">3.2. Zest⢠in 2 minutes</a></span></dt><dt><span class="section"><a href="#ten-minutes-intro">3.3. Zest⢠in 10 minutes</a></span></dt><dt><span class="section"><a href="#thirty-minutes-intro">3.4. Zest⢠in 30 minutes</a></span></dt><dt><span class="section"><a href="#two-hours-intro">3.5. Zest⢠in 2 hours</a></span></dt><dt><span class="section"><a href="#howto-depend-on-qi4j">3.6. Depend on Zest⢠in your build</a></span></dt><dt><span class="section"><a href="#howto-assemble-application">3.7. Assemble an Application</a></span></dt><dt><span class="section"><a href="#tut-composites">3.8. Transient Composites Tutorial</a></span></dt><dt><span class="sect ion"><a href="#tut-services">3.9. Services Composites Tutorial</a></span></dt><dt><span class="section"><a href="#howto-contextual-fragments">3.10. Use contextual fragments</a></span></dt><dt><span class="section"><a href="#howto-leverage-properties">3.11. Leverage Properties</a></span></dt><dt><span class="section"><a href="#howto-create-constraint">3.12. Create a Constraint</a></span></dt><dt><span class="section"><a href="#howto-create-concern">3.13. Create a Concern</a></span></dt><dt><span class="section"><a href="#howto-create-sideeffect">3.14. Create a SideEffect</a></span></dt><dt><span class="section"><a href="#howto-create-entity">3.15. Create an Entity</a></span></dt><dt><span class="section"><a href="#howto-configure-service">3.16. Configure a Service</a></span></dt><dt><span class="section"><a href="#howto-invocation-annotation">3.17. Use @Invocation</a></span></dt><dt><span class="section"><a href="#howto-use-io">3.18. Use I/O API</a></span></dt><dt><span class="sectio n"><a href="#build-system">3.19. Build System</a></span></dt><dt><span class="section"><a href="#community-docs">3.20. Writing Zest⢠Documentation</a></span></dt></dl></dd><dt><span class="section"><a href="#javadocs">4. Javadoc</a></span></dt><dd><dl><dt><span class="section"><a href="#_javadocs">4.1. JavaDocs</a></span></dt></dl></dd><dt><span class="section"><a href="#samples">5. Samples</a></span></dt><dd><dl><dt><span class="section"><a href="#_overview_2">5.1. Overview</a></span></dt><dt><span class="section"><a href="#sample-dci">5.2. DCI Sample</a></span></dt><dt><span class="section"><a href="#sample-dci-cargo">5.3. DCI Cargo Sample</a></span></dt><dt><span class="section"><a href="#sample-forum">5.4. Forum Sample</a></span></dt><dt><span class="section"><a href="#sample-car-rental">5.5. Car Rental Sample</a></span></dt><dt><span class="section"><a href="#sample-sql-support">5.6. SQL Support Sample</a></span></dt><dt><span class="section"><a href="#sample-swing">5.7. S wing Bindings Sample</a></span></dt></dl></dd><dt><span class="section"><a href="#core">6. Core</a></span></dt><dd><dl><dt><span class="section"><a href="#_overview_3">6.1. Overview</a></span></dt><dt><span class="section"><a href="#core-api">6.2. Core API</a></span></dt><dt><span class="section"><a href="#core-bootstrap-assembly">6.3. Core Bootstrap</a></span></dt><dt><span class="section"><a href="#core-testsupport">6.4. Core Test Support</a></span></dt><dt><span class="section"><a href="#core-functional">6.5. Core Functional API</a></span></dt><dt><span class="section"><a href="#core-io">6.6. Core I/O API</a></span></dt><dt><span class="section"><a href="#core-spi">6.7. Core Extension SPI</a></span></dt><dt><span class="section"><a href="#core-runtime">6.8. Core Runtime</a></span></dt></dl></dd><dt><span class="section"><a href="#libraries">7. Libraries</a></span></dt><dd><dl><dt><span class="section"><a href="#_overview_5">7.1. Overview</a></span></dt><dt><span class="section">< a href="#library-alarm">7.2. Alarms</a></span></dt><dt><span class="section"><a href="#library-circuitbreaker">7.3. Circuit Breaker</a></span></dt><dt><span class="section"><a href="#library-constraints">7.4. Constraints</a></span></dt><dt><span class="section"><a href="#library-conversion">7.5. Conversion</a></span></dt><dt><span class="section"><a href="#library-eventsourcing">7.6. Event Sourcing</a></span></dt><dt><span class="section"><a href="#library-eventsourcing-jdbm">7.7. Event Sourcing - JDBM</a></span></dt><dt><span class="section"><a href="#library-eventsourcing-rest">7.8. Event Sourcing - ReST</a></span></dt><dt><span class="section"><a href="#library-fileconfig">7.9. FileConfig</a></span></dt><dt><span class="section"><a href="#library-http">7.10. HTTP</a></span></dt><dt><span class="section"><a href="#library-invocation-cache">7.11. Invocation Cache</a></span></dt><dt><span class="section"><a href="#library-jmx">7.12. JMX</a></span></dt><dt><span class="section"><a hr ef="#library-locking">7.13. Locking</a></span></dt><dt><span class="section"><a href="#library-logging">7.14. Logging</a></span></dt><dt><span class="section"><a href="#library-osgi">7.15. OSGi</a></span></dt><dt><span class="section"><a href="#library-rdf">7.16. RDF</a></span></dt><dt><span class="section"><a href="#library-rest-client">7.17. ReST Client</a></span></dt><dt><span class="section"><a href="#library-rest-client-primer">7.18. ReST - HATEOAS Primer</a></span></dt><dt><span class="section"><a href="#library-rest-common">7.19. ReST Common</a></span></dt><dt><span class="section"><a href="#library-rest-server">7.20. ReST Server</a></span></dt><dt><span class="section"><a href="#library-scheduler">7.21. Scheduler</a></span></dt><dt><span class="section"><a href="#library-script-groovy">7.22. Groovy Scripting</a></span></dt><dt><span class="section"><a href="#library-script-javascript">7.23. Javascript Scripting</a></span></dt><dt><span class="section"><a href="#lang-scala">7 .24. Scala Support</a></span></dt><dt><span class="section"><a href="#library-servlet">7.25. Servlet</a></span></dt><dt><span class="section"><a href="#library-shiro">7.26. Shiro Security</a></span></dt><dt><span class="section"><a href="#library-shiro-web">7.27. Shiro Web Security</a></span></dt><dt><span class="section"><a href="#library-spring">7.28. Spring Integration</a></span></dt><dt><span class="section"><a href="#library-sql">7.29. SQL</a></span></dt><dt><span class="section"><a href="#library-uid">7.30. UID</a></span></dt><dt><span class="section"><a href="#library-uowfile">7.31. UoWFile</a></span></dt></dl></dd><dt><span class="section"><a href="#extensions">8. Extensions</a></span></dt><dd><dl><dt><span class="section"><a href="#_overview_7">8.1. Overview</a></span></dt><dt><span class="section"><a href="#extension-vs-orgjson">8.2. org.json ValueSerialization</a></span></dt><dt><span class="section"><a href="#extension-vs-jackson">8.3. Jackson ValueSerialization</a></spa n></dt><dt><span class="section"><a href="#extension-vs-stax">8.4. StAX ValueSerialization</a></span></dt><dt><span class="section"><a href="#extension-cache-ehcache">8.5. Ehcache Cache</a></span></dt><dt><span class="section"><a href="#extension-cache-memcache">8.6. Memcache Cache</a></span></dt><dt><span class="section"><a href="#extension-es-memory">8.7. Memory EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-file">8.8. File EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-hazelcast">8.9. Hazelcast EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-jclouds">8.10. JClouds EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-jdbm">8.11. JDBM EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-leveldb">8.12. LevelDB EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-mongodb">8.13. MongoDB EntityStore</a></span></dt><dt><span class="se ction"><a href="#extension-es-preferences">8.14. Preferences EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-redis">8.15. Redis EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-riak">8.16. Riak EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-sql">8.17. SQL EntityStore</a></span></dt><dt><span class="section"><a href="#extension-es-voldemort">8.18. Voldemort EntityStore</a></span></dt><dt><span class="section"><a href="#extension-index-elasticsearch">8.19. ElasticSearch Index/Query</a></span></dt><dt><span class="section"><a href="#extension-index-rdf">8.20. OpenRDF Index/Query</a></span></dt><dt><span class="section"><a href="#extension-index-solr">8.21. Apache Solr Index/Query</a></span></dt><dt><span class="section"><a href="#extension-indexing-sql">8.22. SQL Index/Query</a></span></dt><dt><span class="section"><a href="#extension-metrics-yammer">8.23. Yammer Metrics</a></span></dt><dt><span class=" section"><a href="#extension-migration">8.24. Migration</a></span></dt><dt><span class="section"><a href="#extension-reindexer">8.25. Reindexer</a></span></dt></dl></dd><dt><span class="section"><a href="#tools">9. Tools</a></span></dt><dd><dl><dt><span class="section"><a href="#_overview_8">9.1. Overview</a></span></dt><dt><span class="section"><a href="#tools-envisage">9.2. Envisage</a></span></dt></dl></dd><dt><span class="section"><a href="#glossary">10. Glossary </a></span></dt></dl></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h2 class="title" style="clear: both"><a id="home"></a>1. Zestâ¢</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#_what_is_apache_zest">1.1. What is Apache Zest⢠?</a></span></dt><dt><span class="section"><a href="#_brief_history">1.2. Brief History</a></span></dt></dl></div><div class="important" style="margin-left: 0; margin-right: 10%;"><table border="0" summary="Important"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Important]" src="images/icons/admon/important.png" /></td><th align="left">Important</th></tr><tr><td align="left" valign="top"><p>This is the documentation for <span class="strong"><strong>Zest⢠0</strong></span>. Use the version switcher on the left to browse other +versions documentation.</p></td></tr></table></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h3 class="title"><a id="_what_is_apache_zest"></a>1.1. What is Apache Zest⢠?</h3></div></div></div><p>The short answer is that Apache Zest⢠is a framework for domain centric application development, including evolved +concepts from <a class="ulink" href="http://en.wikipedia.org/wiki/Aspect-oriented_programming"; target="_top">AOP</a>, +<a class="ulink" href="http://en.wikipedia.org/wiki/Dependency_injection"; target="_top">DI</a> and <a class="ulink" href="http://en.wikipedia.org/wiki/Domain-driven_design"; target="_top">DDD</a>.</p><p>Zest⢠is an implementation of Composite Oriented Programming, using the standard Java platform, without the use of any pre-processors or new language elements. Everything you know from Java still applies and you can leverage both -your experience and toolkits to become more productive with Composite Oriented Programming today.</p><p>Moreover, Qi4j⢠enables Composite Oriented Programming on the Java platform, including both Java and Scala as primary -languages as well as many of the plethora of languages running on the JVM as bridged languages.</p><p><span class="inlinemediaobject"><img src="images/intro-qi.png" alt="Qi" /></span></p><p>Qi4j⢠is pronounced "chee for jay". This website is out of scope to explain the many +your experience and toolkits to become more productive with Composite Oriented Programming today.</p><p>Moreover, Zest⢠enables Composite Oriented Programming on the Java platform, including both Java and Scala as primary +languages as well as many of the plethora of languages running on the JVM as bridged languages.</p><p>We strongly recommend the <a class="link" href="#intro" title="2. Introduction">introduction</a> section.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h3 class="title"><a id="_brief_history"></a>1.2. Brief History</h3></div></div></div><p>Apache Zest⢠started its life in 2007 as Qi4jâ¢, initially at OPS4Jâs infrastructure and later on GitHub. +In March 2015, Apache Zest⢠was created with the Qi4j⢠codebase as the base, existing Apache Members as the +bootstrap Project Management Committee (PMC).</p><p><span class="inlinemediaobject"><img src="images/intro-qi.png" alt="Qi" /></span></p><p>Qi4j⢠is pronounced "chee for jay". This website is out of scope to explain the many facets and history of Qi, so we refer the interested to read the <a class="ulink" href="http://en.wikipedia.org/wiki/Qi"; target="_top">lengthy article</a> at Wikipedia. For us, Qi is the force/energy within the body, in this case the Java platform. Something that makes Java -so much better, if it is found and channeled into a greater good.</p><p>We strongly recommend the <a class="link" href="#intro" title="2. Introduction">introduction</a> section.</p></div></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h2 class="title" style="clear: both"><a id="intro"></a>2. Introduction</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#highlights">2.1. Highligts</a></span></dt><dt><span class="section"><a href="#introduction-background">2.2. Background</a></span></dt><dt><span class="section"><a href="#what-is-cop">2.3. What is COP?</a></span></dt><dt><span class="section"><a href="#what-s-an-object-anyway">2.4. Whatâs an Object anyway?</a></span></dt><dt><span class="section"><a href="#state-modeling">2.5. Qi4j and state modeling</a></span></dt><dt><span class="section"><a href="#related">2.6. Related publications & projects</a></s pan></dt></dl></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h3 class="title"><a id="highlights"></a>2.1. Highligts</h3></div></div></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="_principles"></a>Principles</h4></div></div></div><p>Composite Oriented Programming builds on some principles that are not addressed by Object Oriented Programming at all.</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"> +so much better, if it is found and channeled into a greater good.</p></div></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h2 class="title" style="clear: both"><a id="intro"></a>2. Introduction</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#highlights">2.1. Highligts</a></span></dt><dt><span class="section"><a href="#introduction-background">2.2. Background</a></span></dt><dt><span class="section"><a href="#what-is-cop">2.3. What is COP?</a></span></dt><dt><span class="section"><a href="#what-s-an-object-anyway">2.4. Whatâs an Object anyway?</a></span></dt><dt><span class="section"><a href="#state-modeling">2.5. Zest⢠and state modeling</a></span></dt><dt><span class="section"><a href="#related">2.6. Related publications & projects</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a hre f="#idm132692182224">Return to top</a></p><div><h3 class="title"><a id="highlights"></a>2.1. Highligts</h3></div></div></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h4 class="title"><a id="_principles"></a>Principles</h4></div></div></div><p>Composite Oriented Programming builds on some principles that are not addressed by Object Oriented Programming at all.</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"> Behavior depends on Context </li><li class="listitem"> Decoupling is a virtue @@ -65,7 +67,7 @@ Decoupling is a virtue Business Rules matters more. </li><li class="listitem"> Classes are dead, long live interfaces. -</li></ul></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h5 class="title"><a id="_behavior_depends_on_context"></a>Behavior Depends on Context</h5></div></div></div><p>Many objects has life cycles that are more extensive than the simple model that Object Oriented Programming model wants +</li></ul></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h5 class="title"><a id="_behavior_depends_on_context"></a>Behavior Depends on Context</h5></div></div></div><p>Many objects has life cycles that are more extensive than the simple model that Object Oriented Programming model wants us to believe. A few simple examples;</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"> An egg becomes a chicken which in turn becomes food. </li><li class="listitem"> @@ -80,48 +82,48 @@ that Person may live on for a long time. LivingPerson class to a DeadPerson class. In Composite Oriented Programming, it is the same object with different behavior.</p><p>We think that one of the the main flaws in OOP is that it is not object oriented at all, but in fact class oriented. Class is the first class citizen that objects are derived from. Not objects being the first-class citizen to which -one or many classes are assigned.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h5 class="title"><a id="_decoupling_is_virtue"></a>Decoupling is Virtue</h5></div></div></div><p>Decoupling is more important than developers in general think. If you could have every OOP class decoupled from all +one or many classes are assigned.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h5 class="title"><a id="_decoupling_is_virtue"></a>Decoupling is Virtue</h5></div></div></div><p>Decoupling is more important than developers in general think. If you could have every OOP class decoupled from all other classes, it is easy to re-use that class. But when that class references another class and the chain never ends, your chances of re-use diminishes quickly.</p><p>Object Oriented Programming is suffering a lot from this, and many mechanisms have been introduced over time to counter this problem. But in reality, the best we can manage is subsystems of functionality, which client code can re-use. And these subsystems tend to be infrastructure related, since domain models are less prone to be similar enough from one project to the next, and since OOP in reality constrains the the re-use of individual domain classes, we need to re-do -the domain model from scratch ever time.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h5 class="title"><a id="_business_rules_matters_more"></a>Business Rules matters more</h5></div></div></div><p>Smart developers often think that low-level, infrastructure and framework code is more important and more cool to work +the domain model from scratch ever time.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h5 class="title"><a id="_business_rules_matters_more"></a>Business Rules matters more</h5></div></div></div><p>Smart developers often think that low-level, infrastructure and framework code is more important and more cool to work with, than the simple domain model. But in reality, it is the Domain Model that reflects the actual need and pays the bills. Infrastructure is just a necessary evil to get things done.</p><p>If most developers could focus on the Business Rules and Domain Model, and not having to worry about any infrastructure issues, such as persistence, transactions, security or the framework housing it all, the productivity would surge. Eric Evans has written an excellent book about Domain Driven Design, where he goes through the real process that makes the money for companies. However, it is very hard to follow that book, since one is constantly caught up in constraints -irrelevant to the domain model, introduced by the underlying framework, from the so called smart developers.</p><p><span class="inlinemediaobject"><img src="images/classes-are-dead.gif" alt="classes-are-dead.gif" /></span></p><p>Qi4j⢠is trying to address the flaws of OOP and introduce Composite Oriented Programming to the world, without -introducing new programming languages, or awkward constructs. Heck, we donât even use any XML.</p><p>Qi4j⢠is not a framework. It is a new way to write code. Other people might create frameworks using Qi4jâ¢, or create a -framework optimized for Qi4jâ¢, but here at Qi4j⢠we concentrate to make Qi4j⢠behave well in existing frameworks, -application servers, platforms and environments.</p><p>You are to embark on a new journey. Enjoy!</p></div></div></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h3 class="title"><a id="introduction-background"></a>2.2. Background</h3></div></div></div><p>Qi4j is the first Composite Oriented Programming implementation leveraging the Java 5 platform, so that everything you -know from Java 5 still applies. You can mix Qi4j with your ordinary Java code as much as you want. All your existing -Java tools works just like before, and Qi4j does not introduce any new programming language, no special development -tools needed and no XML is required.</p><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="_purpose"></a>Purpose</h4></div></div></div><p>Qi4j addresses the programming problems from the top-down, starting with the Domain Model and Business Rules needs, +irrelevant to the domain model, introduced by the underlying framework, from the so called smart developers.</p><p><span class="inlinemediaobject"><img src="images/classes-are-dead.gif" alt="classes-are-dead.gif" /></span></p><p>Zest⢠is trying to address the flaws of OOP and introduce Composite Oriented Programming to the world, without +introducing new programming languages, or awkward constructs. Heck, we donât even use any XML.</p><p>Zest⢠is not a framework. It is a new way to write code. Other people might create frameworks using Zestâ¢, or create a +framework optimized for Zestâ¢, but here at Zest⢠we concentrate to make Zest⢠behave well in existing frameworks, +application servers, platforms and environments.</p><p>You are to embark on a new journey. Enjoy!</p></div></div></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h3 class="title"><a id="introduction-background"></a>2.2. Background</h3></div></div></div><p>Zest⢠is the first Composite Oriented Programming implementation leveraging the Java 5 platform, so that everything you +know from Java 5 still applies. You can mix Zest⢠with your ordinary Java code as much as you want. All your existing +Java tools works just like before, and Zest⢠does not introduce any new programming language, no special development +tools needed and no XML is required.</p><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h4 class="title"><a id="_purpose"></a>Purpose</h4></div></div></div><p>Zest⢠addresses the programming problems from the top-down, starting with the Domain Model and Business Rules needs, and let those requirements flow downwards in the software stack and dictate the requirements for underlying layers such as persistence, messaging, querying and more. This means that the business value developer is left to concentrate on the domain models and the actual application bringing the value, instead of creating massive amounts -of glue code to tie underlying technologies together.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="_problem_descriptions"></a>Problem Descriptions</h4></div></div></div><p>Qi4j didnât appear out of the blue, when the founders of the project had nothing better to do. It is the result of +of glue code to tie underlying technologies together.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h4 class="title"><a id="_problem_descriptions"></a>Problem Descriptions</h4></div></div></div><p>Zest⢠didnât appear out of the blue, when the founders of the project had nothing better to do. It is the result of observation of problems in real applications, and the experience from previous attempts to address or correct these -problems, that has led to the Qi4j vision.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="_object_oriented_programming_oop"></a>Object Oriented Programming (OOP)</h4></div></div></div><p>How can OOP be a problem? We and others have observed that there is a fundamental flaw in the OOP model. In fact, we +problems, that has led to the Zest⢠vision.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h4 class="title"><a id="_object_oriented_programming_oop"></a>Object Oriented Programming (OOP)</h4></div></div></div><p>How can OOP be a problem? We and others have observed that there is a fundamental flaw in the OOP model. In fact, we would like to even state that OOP as it is commonly practiced today is not object oriented at all. The object is not the primary citizen, instead the class is the primary artifact. In most mainstream OOP languages, Objects are derived from classes, not that classes are assigned to created objects. Therefore, we think it should have been called Class Oriented Programming. We can also see this class focus in many of the technologies in Java today: in Spring you declare -class names in application contexts, JSP uses class names to declare beans and so forth.</p><p>This in turn leads to that there is no good OOP solution for the problem we describe below.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="_behavior_depends_on_context_2"></a>Behavior depends on Context</h4></div></div></div><p>Once you start thinking of "Behavior depends on Context", you have a hard time understanding how people for the last 20 -years or so of Object Oriented Programming (OOP) has ignored this fact.</p><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h5 class="title"><a id="_who_am_i"></a>Who am I?</h5></div></div></div><p>When I sitting in front of the computer, I am a software developer, but if I go out in the jungle, I am suddenly +class names in application contexts, JSP uses class names to declare beans and so forth.</p><p>This in turn leads to that there is no good OOP solution for the problem we describe below.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h4 class="title"><a id="_behavior_depends_on_context_2"></a>Behavior depends on Context</h4></div></div></div><p>Once you start thinking of "Behavior depends on Context", you have a hard time understanding how people for the last 20 +years or so of Object Oriented Programming (OOP) has ignored this fact.</p><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h5 class="title"><a id="_who_am_i"></a>Who am I?</h5></div></div></div><p>When I sitting in front of the computer, I am a software developer, but if I go out in the jungle, I am suddenly hunter-gatherer and prey. A large set of me is the same, but my interaction with the surroundings, i.e. the context, is very different. I need different interfaces, so to speak, in these two different contexts.</p><p>Now, the above example is perhaps a bit extreme, but we see it in everyday life of the developer. When an object is stored in the database it is of a different class, than when it is transported to the client and possibly when it is displayed in the GUI. We see the effect of this problem in many of the design patterns and so called "best practices" -in Java EE development. Facades, delegation, data transport objects and many more.</p></div></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="_coupling"></a>Coupling</h4></div></div></div><p>The OOP proponents once proclaimed that classes can be re-used, since the code is encapsulated with the class, so the +in Java EE development. Facades, delegation, data transport objects and many more.</p></div></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h4 class="title"><a id="_coupling"></a>Coupling</h4></div></div></div><p>The OOP proponents once proclaimed that classes can be re-used, since the code is encapsulated with the class, so the class is an independent unit which lends itself well to re-use. In reality, however, we have found that classes becomes tightly coupled with many other classes in their neighborhood, leading to impossibilities of single class re-use. Many tricks are introduced to minimize the "Coupling Hell", such as Inversion of Control and Dependency Injection. Although those tools are good, the underlying problem remains.</p><p>Why do we end up with large coupled class network graphs?</p><p>Essentially, it boils down to "scope". Classes are too large, their scope is too large, and for each small functional unit within the class, there will be additional coupling to other classes. And this often progresses to the full -boundary of the entire domain the class remains in.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="_application_layer_impedance_mismatch"></a>Application layer impedance mismatch</h4></div></div></div><p>Almost all technologies used in modern software development, starts by looking at an infrastructural problem and try to +boundary of the entire domain the class remains in.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h4 class="title"><a id="_application_layer_impedance_mismatch"></a>Application layer impedance mismatch</h4></div></div></div><p>Almost all technologies used in modern software development, starts by looking at an infrastructural problem and try to solve that the best way. This is often done in a vacuum and layers on top will be struggling to map or translate the solution into the higher abstraction, and the higher up we get, the harder it becomes to ignore the assumptions, problems and limitations of the underlying technologies. It is also common that the underlying technologies "bleeds" @@ -131,48 +133,48 @@ often, the most skilled developers end u Another interesting consequence is that each layer needs to anticipate every single use-case - real, potential or perceived - and deal with it in a specifiable and useful manner. This leads to overly complex solutions, compared to if the system is built from the top layer down, where each layer beneath knows exactly what is expected from it, and only -needs to handle those use-cases.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="_abstracting_away_meaning"></a>Abstracting away meaning.</h4></div></div></div><p>To paraphrase a famous proverb about a hammer: "If all you have are objects, everything looks like a dependency." +needs to handle those use-cases.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h4 class="title"><a id="_abstracting_away_meaning"></a>Abstracting away meaning.</h4></div></div></div><p>To paraphrase a famous proverb about a hammer: "If all you have are objects, everything looks like a dependency." We think that increasing abstraction often also increases complexity, and that the abstraction benefits are somewhat linear whereas the complexity negatives are exponential. So, our conclusion is that by making no distinction between different kinds of objects, many sound technologies run into incredibly difficult problems. The implementation of the programming platform (e.g. Java) is of course easier to implement with a hefty amount of scope reduction into as few as possible abstractions. But that is not the situation for the user. The abstraction is then required to be reversed when the rubber hits the road, e.g. ORM mapping must be declared explicitly by the programmer, often using separate tools -and languages.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="_solution"></a>Solution</h4></div></div></div><p>We think the solution was expressed more than 2500 years ago, first by Indian scholars and slightly later by Leucippus +and languages.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h4 class="title"><a id="_solution"></a>Solution</h4></div></div></div><p>We think the solution was expressed more than 2500 years ago, first by Indian scholars and slightly later by Leucippus and Democritus. We are of course talking about atoms, and by using really small building blocks, we can express arbitrarily complex structures. By reducing the classes into what we in Composite Oriented Programming call Fragments, we limit the coupling network graph substantially. Re-use of Fragments becomes a reality, and by combination of Fragments, we compose larger -structures, the Composites.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="_composition"></a>Composition</h4></div></div></div><p>Composite Oriented Programming also view the object, we call it the Composite instance, as the first class citizen. The +structures, the Composites.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h4 class="title"><a id="_composition"></a>Composition</h4></div></div></div><p>Composite Oriented Programming also view the object, we call it the Composite instance, as the first class citizen. The Composite instance can be cast to any context, meaning a different behavior can be applied to the Composite instance, without affecting its underlying state. And back. This in turn means that we can for instance create a ServerContextualInvoiceEntity, transport that across to a client, cast it to a GuiContextualInvoiceEntity do the modifications to the underlying state, possibly using extra interfaces and methods for interacting with the GUI environment, and then transport the modified object back to the server, cast it back to the -ServerContextualInvoiceEntity, and then persist the changes.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="_domain_driven_design_focus"></a>Domain Driven Design focus</h4></div></div></div><p>Composite Oriented Programming is heavily influenced by the book "Domain Driven Design" by Eric Evans. And we are +ServerContextualInvoiceEntity, and then persist the changes.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h4 class="title"><a id="_domain_driven_design_focus"></a>Domain Driven Design focus</h4></div></div></div><p>Composite Oriented Programming is heavily influenced by the book "Domain Driven Design" by Eric Evans. And we are trying to use his analysis of the problem to provide the mechanisms needed to get the job done quicker and more reliably. Mr Evans talks about Applications, Layers, Modules, Specifications, SideEffects and so forth, and all of -these should be present in a Composite Oriented Programming implementation, and to a large extent it is in Qi4j.</p></div></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h3 class="title"><a id="what-is-cop"></a>2.3. What is COP?</h3></div></div></div><p>We found this very well written blog entry on the Internet, which very well describes what Composite Oriented +these should be present in a Composite Oriented Programming implementation, and to a large extent it is in Zestâ¢.</p></div></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h3 class="title"><a id="what-is-cop"></a>2.3. What is COP?</h3></div></div></div><p>We found this very well written blog entry on the Internet, which very well describes what Composite Oriented Programming really is.</p><p>The article uses C# and a "show by example" approach to explaining COP, and this shows clearly that COP is not -Java specific, and although Qi4j was (to our knowledge) first to introduce the name, it applies across languages and +Java specific, and although Zest⢠was (to our knowledge) first to introduce the name, it applies across languages and potentially deserves one or more languages on its own.</p><p>The article is re-published here, as allowed by the <a class="ulink" href="http://msdn.microsoft.com/en-us/windowsmobile/bb264332.aspx"; target="_top">Microsoft Permissive License</a> , more recently known as <a class="ulink" href="http://www.opensource.org/licenses/MS-PL"; target="_top">Microsoft Public License</a>. The content below -is NOT under the usual <a class="ulink" href="http://www.opensource.org/licenses/Apache-2.0"; target="_top">Apache License</a>.</p><p>We would like to thank Fredrik Kalseth for his explicit approval as well.</p><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="_ulink_url_http_iridescence_no_post_composite_oriented_programming_aspx_composite_oriented_programming_ulink"></a><a class="ulink" href="http://iridescence.no/post/composite-oriented-programming.aspx"; target="_top">Composite Oriented Programming</a></h4></div></div></div><p>Iâve written a series of post on AOP lately (here, here and here), and in the last part I promised to tackle mixins +is NOT under the usual <a class="ulink" href="http://www.opensource.org/licenses/Apache-2.0"; target="_top">Apache License</a>.</p><p>We would like to thank Fredrik Kalseth for his explicit approval as well.</p><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h4 class="title"><a id="_ulink_url_http_iridescence_no_post_composite_oriented_programming_aspx_composite_oriented_programming_ulink"></a><a class="ulink" href="http://iridescence.no/post/composite-oriented-programming.aspx"; target="_top">Composite Oriented Programming</a></h4></div></div></div><p>Iâve written a series of post on AOP lately (here, here and here), and in the last part I promised to tackle mixins and introductions in a future post. When I was doing my research for just that, I came cross a Java framework (just -humor me :p) called Qi4j (thatâs <span class="emphasis"><em>chee for jay</em></span>), written by Swedish Richard Ãberg, pioneering the idea of Composite +humor me :p) called Zest⢠(thatâs <span class="emphasis"><em>chee for jay</em></span>), written by Swedish Richard Ãberg, pioneering the idea of Composite Oriented Programming, which instantly put a spell on me. Essentially, it takes the concepts from Aspect Oriented Programming to the extreme, and for the past week Iâve dug into it with a passion. This post is the first fruits of -my labor.</p><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h5 class="title"><a id="_oop_is_not_object_oriented"></a>OOP is Not Object Oriented!</h5></div></div></div><p>One of the things that Richard Ãberg argues, is that OOP is not really object oriented at all, but rather class -oriented. As the Qi4j website proclaims, "class is the first class citizen that objects are derived from. Not objects +my labor.</p><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h5 class="title"><a id="_oop_is_not_object_oriented"></a>OOP is Not Object Oriented!</h5></div></div></div><p>One of the things that Richard Ãberg argues, is that OOP is not really object oriented at all, but rather class +oriented. As the Zest⢠website proclaims, "class is the first class citizen that objects are derived from. Not objects being the first-class citizen to which one or many classes are assigned". Composite oriented programming (COP) then, tries to work around this limitation by building on a set of core principles; that behavior depends on context, that decoupling is a virtue, and that business rules matter more. For a short and abstract explanation of COP, <a class="link" href="#introduction-background" title="2.2. Background">see this page</a>. In the rest of this post Iâll try and explain some of its easily graspable benefits through a set of code examples, and then in a future post weâll look at how Iâve morphed the AOP framework I started developing in the previous posts in this series into a lightweight COP framework that can actually make -it compile and run.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h5 class="title"><a id="_lead_by_example"></a>Lead by Example</h5></div></div></div><p><span class="emphasis"><em>Lets pause for a short aside: obviously the examples presented here are going to be architectured beyond any rational +it compile and run.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h5 class="title"><a id="_lead_by_example"></a>Lead by Example</h5></div></div></div><p><span class="emphasis"><em>Lets pause for a short aside: obviously the examples presented here are going to be architectured beyond any rational sense, but the interesting part lies in seeing the bigger picture; imagine the principles presented here applied on a much larger scale and Iâm sure you can see the benefits quite clearly when we reach the end.</em></span></p><p>Imagine that we have a class Division, which knows how to divide one number by another:</p><pre class="programlisting brush: c#">public class Division { @@ -207,7 +209,7 @@ intertwined. To what extent is this clas calculations? Not very, at least not unless we refactored it. We could make the Calculate method and the properties virtual, and thus use inheritance to modify the logic of the calculation - and since this is a tiny example, it would probably look OK. But again, think bigger - how would this apply to a huge API? It would easily become quite difficult -to manage as things got more and more complex.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h5 class="title"><a id="_design_by_composition"></a>Design by Composition</h5></div></div></div><p>With a COP framework, we can implement each aspect as a separate object and then treat them as <span class="emphasis"><em>mixins</em></span> which blend +to manage as things got more and more complex.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h5 class="title"><a id="_design_by_composition"></a>Design by Composition</h5></div></div></div><p>With a COP framework, we can implement each aspect as a separate object and then treat them as <span class="emphasis"><em>mixins</em></span> which blend together into a meaningful <span class="emphasis"><em>composite</em></span>. Sounds confusing? Lets refactor the above example using an as of yet imaginary COP framework for .NET (which Iâm currently developing and will post the source code for in a follow-up post), and itâll all make sense (hopefully!).</p><p>Above, we identified the four different aspects in the Division class - so letâs implement each of them. First, we @@ -343,8 +345,8 @@ public interface ISubtraction : ICalcula posts. Iâve already implemented a prototype framework that supports the above examples, which builds on my <a class="ulink" href="http://www.iridescence.no/Posts/Implementing-an-AOP-Framework-Part-2.aspx"; target="_top">previously posted AOP framework</a>, and Iâll post the source code for that soon. If you want to dig deeper right now (and donât mind -a bit of Java), then I suggest you head over to the Qi4j website and poke about there. -<a class="ulink" href="http://rickardoberg.wordpress.com/"; target="_top">Richard Ãbergs blog</a> also provides great insight.</p></div></div></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h3 class="title"><a id="what-s-an-object-anyway"></a>2.4. Whatâs an Object anyway?</h3></div></div></div><p>In OOP the main idea is that we should model our reality by creating Objects. Objects have state, and they have methods. +a bit of Java), then I suggest you head over to the Zest⢠website and poke about there. +<a class="ulink" href="http://rickardoberg.wordpress.com/"; target="_top">Richard Ãbergs blog</a> also provides great insight.</p></div></div></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h3 class="title"><a id="what-s-an-object-anyway"></a>2.4. Whatâs an Object anyway?</h3></div></div></div><p>In OOP the main idea is that we should model our reality by creating Objects. Objects have state, and they have methods. Methods in an object are used to operate on the internal state and understands the domain that is being modeled.</p><p>By contrast, in procedural programming the focus is on algorithms, which can use several data structures to perform some task. The focus is on what is going on, rather than the "objects" involved.</p><p>With OOP it becomes more difficult to "read" algorithms, as they are spread out in many objects that interact. With procedural programming it becomes difficult to encapsulate and reuse functionality. Both represent extremes, neither of @@ -362,7 +364,7 @@ there will be an interface, and for each This mixin can be specific for that composite implementation, or it can be generic and reused. The key point is that it is the OBSERVER of the object, meaning, the algorithm, that gets to decide what the object should be able to do.</p><p>This is the same in real life. I donât get to decide how I communicate with you. I have to use english, and I have to use email, and I have to send it to a specific mailing list. It is the algorithm of the interaction between us, the -Qi4j dev mailing list, that has set these rules, not <span class="strong"><strong>I</strong></span> as a participant in this interaction. The same should, +Zest⢠dev mailing list, that has set these rules, not <span class="strong"><strong>I</strong></span> as a participant in this interaction. The same should, obviously, be the case for objects.</p><p>So, with the understanding that algorithms should define roles for collaborating objects, and objects should then implement these in order to participate in these algorithms, it should be trivial to realize that what has passed for OOP so far, in terms of "class oriented programming", where this role-focus of objects is difficult to achieve, if not @@ -370,7 +372,7 @@ even impossible, is just plain wrong. I designated as "coordinator", which then delegates to a number of other objects in order to implement the various roles. This "solution", which is caused by this fundamental flaw in "class oriented programming", is essentially a hack, and causes a number of other problems, such as the "self schizophrenia" problem, whereby there is no way to tell where the -object really is. There is no "this" pointer that has any relevant meaning.</p><p>The Composite pattern, as implemented in COP and Qi4j, gets around this by simply saying that the composite, as a +object really is. There is no "this" pointer that has any relevant meaning.</p><p>The Composite pattern, as implemented in COP and Zestâ¢, gets around this by simply saying that the composite, as a whole, is an object. Tada, we now have a "this" pointer, and a coherent way to deal with the object graph as though it was a single object. We are now able to get back to the strengths of the procedural approach, which allows the implementer of the algorithm to define the roles needed for the algorithm. The roles can either be specific to an @@ -378,7 +380,7 @@ algorithm, or they can be shared between algorithm is not too tightly encoded in the composites, thereby making the algorithms more reusable, and making it less necessary to read composite code when trying to understand algorithms. The assumption here is that we are going to write more algorithms than composites, therefore it has to be easy to ready algorithms, and only when necessary dive down into -composite code.</p><p>When talking about Composites as Objects in Qi4j it is most relevant to look at Entities, since these represent physical +composite code.</p><p>When talking about Composites as Objects in Zest⢠it is most relevant to look at Entities, since these represent physical objects in a model, rather than algorithms or services, or other non-instance-oriented things.</p><p>If Entities should implement roles, via mixins, in order to interact with each other through algorithms, then the majority of their behaviour should be put into those role-mixins. These are exposed publically for clients to use. However, the state that is required to implement these roles should not be exposed publically, as they represent @@ -410,7 +412,7 @@ general allow our role-oriented approach generally reusable, and the state interfaces are usually reusable. This minimizes the need for us to go into the mixin code and read it. If we have read the mixin code once, and the same mixin is reused between objects, then this makes it easier for us to understand it the next time we see it being used in another algorithm.</p><p>To summarize thus far, we have looked at why OOP so far has not worked out, why this is the case, and how COP deals -with it, and how we can implement a better solution of Entities using Qi4j. All is well!</p><p>The next step is to start using these Entities in algorithms. Algorithms are usually stateless, or at least they donât +with it, and how we can implement a better solution of Entities using Zestâ¢. All is well!</p><p>The next step is to start using these Entities in algorithms. Algorithms are usually stateless, or at least they donât have any state that survives the execution of the algorithm. There is input, some calculation, and then output. In other words, our notion of services fit perfectly here!</p><p>Algorithms, then, should(/could?) be modeled using services. If an algorithm needs other algorithms to compute something, that is, if a service needs another service to do something, we can accomplish this using dependency @@ -440,14 +442,14 @@ would need to get the three objects invo selected item in a list, and "TaskExecutor to" could be a user designated from a popup dialog. These three are then taken by the context and used to execute the "delegate" interaction, which performs all the steps necessary.</p><p>The interaction method "delegate" is testable, both with mocks of the input, and with specific instances of the various roles. The implementations are also testable, and if the same mixin is used over and over for the implementation, then -only one set of tests is needed for each role interface.</p><p>To summarize we have in COP/Qi4j a way to get the best from procedural and object-oriented programming. As we have seen +only one set of tests is needed for each role interface.</p><p>To summarize we have in COP/Zest⢠a way to get the best from procedural and object-oriented programming. As we have seen the functionality falls into three categories, the entities implementing objects, the services implementing interactions, and the user interface implementing the context. This also maps well to the ideas of ModelViewController, which in turn maps well to the new ideas from Mr Reenskaug (inventor of MVC) called DCI: Data-Context-Interaction. As a -side-effect of this discussion we have therefore also seen how COP/Qi4j can be used to implement DCI, which is an +side-effect of this discussion we have therefore also seen how COP/Zest⢠can be used to implement DCI, which is an important next step in understanding objects and their interactions, the fundamentals of which (I believe) are captured on this page.</p><p>Thatâs it. Well done if youâve read this far :-)</p><p>Comments and thoughts to qi4j-dev forum at Google Groups on this are highly appreciated. This is very very important topics, -and crucial to understanding/explaining why COP/Qi4j is so great! :-)</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h3 class="title"><a id="state-modeling"></a>2.5. Qi4j and state modeling</h3></div></div></div><p>(From Rickard Obergâs blog, <a class="ulink" href="http://www.jroller.com/rickard/entry/qi4j_and_state_modeling"; target="_top">http://www.jroller.com/rickard/entry/qi4j_and_state_modeling</a>, 2009-02-19)</p><p>In the Qi4j project we strive to being able to express our domain as directly as possible, with as little translation +and crucial to understanding/explaining why COP/Zest⢠is so great! :-)</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h3 class="title"><a id="state-modeling"></a>2.5. Zest⢠and state modeling</h3></div></div></div><p>(From Rickard Obergâs blog, <a class="ulink" href="http://www.jroller.com/rickard/entry/qi4j_and_state_modeling"; target="_top">http://www.jroller.com/rickard/entry/qi4j_and_state_modeling</a>, 2009-02-19)</p><p>In the Zest⢠project we strive to being able to express our domain as directly as possible, with as little translation as possible between how we think about a domain and how it is actually coded. This then affects our entire view of how application frameworks should be constructed, and what we consider good and bad ways of implementing certain features.</p><p>One part which is a good example of this is persistent state modeling. In other approaches and frameworks one would @@ -457,11 +459,11 @@ If POJOs are used for both Entities and in our heads when talking about them, always keeping mind what the POJO is doing in any particular context. In Domain Driven Design terms, POJOs are not in our Ubiquitous Language.</p><p>From a DDD perspective we want to talk about Entities and Values, Properties and Associations. If our code does not reflect this, then there is translation going on, and translation inevitably leads to information loss. -In Qi4j, where Composites and not Objects, are the basic construct, we have created specialized forms to model these +In Zestâ¢, where Composites and not Objects, are the basic construct, we have created specialized forms to model these concepts more explicitly. We have EntityComposites and ValueComposites, each with different ways of creating them and managing them. Both EntityComposites and ValueComposites can then have Properties, as first-class objects, but Properties in -ValueComposites are always immutable.</p><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="_entities"></a>Entities</h4></div></div></div><p>Hereâs an example of how you could define an EntityComposite:</p><pre class="programlisting brush: java">interface PersonEntity +ValueComposites are always immutable.</p><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h4 class="title"><a id="_entities"></a>Entities</h4></div></div></div><p>Hereâs an example of how you could define an EntityComposite:</p><pre class="programlisting brush: java">interface PersonEntity extends EntityComposite { Property<String> givenName(); @@ -476,7 +478,7 @@ Entities, so thatâs all taken care So if you speak about Entities in your domain discussions, each having Properties, then you can put that down in code pretty much as-is. This is, to me, a huge advantage over other ways of doing it, including POJO modeling (which lose clarity), UML -modeling (which has roundtrip problems), DSL modeling (which lose tools support), and whatnot.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="_roles"></a>Roles</h4></div></div></div><p>If you want to get picky about it, the above example is probably not how you would model Person. Having a name is +modeling (which has roundtrip problems), DSL modeling (which lose tools support), and whatnot.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h4 class="title"><a id="_roles"></a>Roles</h4></div></div></div><p>If you want to get picky about it, the above example is probably not how you would model Person. Having a name is just one role that a Person has to play, and since Composite Oriented Programming is all about using roles and context instead of classes you would probably do something like this instead:</p><pre class="programlisting brush: java">interface Nameable { @@ -500,12 +502,12 @@ their initial values be set to a default For Strings this is the empty string, for primitives they are what you would expect. For Collections they are set to empty collections of the type indicated. "@UseDefaults Property<List<String>> addresses();" would be initialized to an empty ArrayList, for example.</p><p>In addition I have set surName() to be @Optional. -In Qi4j we have defined all properties to be not-null as the default, and the same goes for all parameters in method +In Zest⢠we have defined all properties to be not-null as the default, and the same goes for all parameters in method invocations. If you explicitly want to allow properties to be null, so that for example "Madonna" would be an acceptable name, then you can mark it as @Optional. We prefer @Optional to @Nullable since it better expresses the intent from a domain perspective. -Avoiding technical terms as much as possible is a another goal (which is damn hard to reach!).</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="_values"></a>Values</h4></div></div></div><p>If you want to get really picky about it, not even the above would be a real example. +Avoiding technical terms as much as possible is a another goal (which is damn hard to reach!).</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h4 class="title"><a id="_values"></a>Values</h4></div></div></div><p>If you want to get really picky about it, not even the above would be a real example. You may want to encapsulate the two properties into one value instead, so that you can more easily perform validation checks when they are updated. What you want are ValueComposites:</p><pre class="programlisting brush: java">interface NameValue extends ValueComposite @@ -524,7 +526,7 @@ But since NameValue extends ValueComposi of ValueComposite, and thereâs no way to "opt out" of it.</p><p>By introducing one more level in the state model you have created an easy way to access the name as a whole and hand it around the system, instead of as two separate properties. Since it is immutable you are also ensured that noone can change it without going through the Entity, and you can -also share instances of the name without having to worry about thread-safety.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="_privatizing_state"></a>Privatizing state</h4></div></div></div><p>The above is already a great step ahead in terms of how you can model your state more easily than having to use POJOs +also share instances of the name without having to worry about thread-safety.</p></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h4 class="title"><a id="_privatizing_state"></a>Privatizing state</h4></div></div></div><p>The above is already a great step ahead in terms of how you can model your state more easily than having to use POJOs to sort of "fake" the features Iâm describing above, and thereâs also a ton of cool features and consequences of the whole thing Iâm skipping here, for brevity. One of the problems with POJO models that usually come up is that your getters and setters get exposed to clients, @@ -532,7 +534,7 @@ and so functionality tend to not be put the Entity into a bunch of places. What should have been a neat and tidy little package is instead a anorectic little thing whose guts lay splashed around your code, looking all soggy and unappetizing.</p><p>What to do about this? -One of the great inventions of Qi4j, I believe, is the notion of private mixins. +One of the great inventions of Zestâ¢, I believe, is the notion of private mixins. That we can have mixins in an object which are explicitly HIDDEN from usage outside of it. How can we use this for state modeling? What youâd want to do is to model the state of an Entity as a private mixin, which is hidden from clients, and then @@ -574,10 +576,10 @@ So you can make a UI widget for listing a PersonEntity or Nameable.</p><p>For extra credit you could move the construction of "fullName" into a method on the NameValue, so that the value is not only a dumb data container, but can also perform useful operations on itself. And for the performance aware, donât worry, the mixin is lazy-loaded, so if the particular usecase handling the -Entity doesnât need the "Listable" interface the mixin will never be instantiated.</p><p>And so much moreâ¦</p><p>The above is just a small taste of what you can do with state modeling in Qi4j. +Entity doesnât need the "Listable" interface the mixin will never be instantiated.</p><p>And so much moreâ¦</p><p>The above is just a small taste of what you can do with state modeling in Zestâ¢. There is also support for associations and many-associations, the notion of aggregates, and a complete pluggable system for persistence and indexing/querying of data. -To end with, hereâs a sample of how some other state modeling concepts can be expressed in Qi4j:</p><pre class="programlisting brush: java">interface PersonEntity +To end with, hereâs a sample of how some other state modeling concepts can be expressed in Zestâ¢:</p><pre class="programlisting brush: java">interface PersonEntity extends EntityComposite { Association<PersonEntity> father(); @@ -593,10 +595,10 @@ interface BookNoteEntity Association<BookEntity> book(); } -</pre><p>I hope they are self-explanatory.</p><p>My hope is that with Composite Oriented Programming and Qi4j we can come one step closer to being able to express our -domain as clearly as possible in code.</p></div></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h3 class="title"><a id="related"></a>2.6. Related publications & projects</h3></div></div></div><p>Qi4j addresses a wide range of concepts, the related publications and projects youâll find in this section span accross +</pre><p>I hope they are self-explanatory.</p><p>My hope is that with Composite Oriented Programming and Zest⢠we can come one step closer to being able to express our +domain as clearly as possible in code.</p></div></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h3 class="title"><a id="related"></a>2.6. Related publications & projects</h3></div></div></div><p>Zest⢠addresses a wide range of concepts, the related publications and projects youâll find in this section span accross all theses concepts. Please note that this is not an exhaustive list but only some pointers to help you understand which -principles Qi4j is based on.</p><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="_publications"></a>Publications</h4></div></div></div><p>In chronological order, related publications:</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p class="simpara"> +principles Zest⢠is based on.</p><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h4 class="title"><a id="_publications"></a>Publications</h4></div></div></div><p>In chronological order, related publications:</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p class="simpara"> <span class="strong"><strong>Object-oriented Software Construction</strong></span> </p><p class="simpara">by Bertrand Meyer - 1988</p><p class="simpara">"<span class="emphasis"><em>The comprehensive reference on all aspects of object technology, from design principles to O-O techniques, Design by Contract, O-O analysis, concurrency, persistence, abstract data types and many more. Written by a pioneer in the field, @@ -690,7 +692,7 @@ information. This simple notion leads to </p><p class="simpara">by Martin Fowler - WIP</p><p class="simpara">"<span class="emphasis"><em>Capture all changes to an application state as a sequence of events.</em></span>"</p><p class="simpara"><a class="ulink" href="http://martinfowler.com/eaaDev/EventSourcing.html"; target="_top">http://martinfowler.com/eaaDev/EventSourcing.html</a></p></li><li class="listitem"><p class="simpara"> <span class="strong"><strong>Event Collaboration</strong></span> </p><p class="simpara">by Martin Fowler - WIP</p><p class="simpara">"<span class="emphasis"><em>Multiple components work together by communicating with each other by sending events when their internal state -changes.</em></span>"</p><p class="simpara"><a class="ulink" href="http://martinfowler.com/eaaDev/EventCollaboration.html"; target="_top">http://martinfowler.com/eaaDev/EventCollaboration.html</a></p></li></ul></div></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="_projects"></a>Projects</h4></div></div></div><p><span class="emphasis"><em>Pêle-mêle</em></span>, inspiring, inspired, alternatives or simply related:</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p class="simpara"> +changes.</em></span>"</p><p class="simpara"><a class="ulink" href="http://martinfowler.com/eaaDev/EventCollaboration.html"; target="_top">http://martinfowler.com/eaaDev/EventCollaboration.html</a></p></li></ul></div></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm132692182224">Return to top</a></p><div><h4 class="title"><a id="_projects"></a>Projects</h4></div></div></div><p><span class="emphasis"><em>Pêle-mêle</em></span>, inspiring, inspired, alternatives or simply related:</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p class="simpara"> <span class="strong"><strong>AspectJ</strong></span> </p><p class="simpara">"<span class="emphasis"><em>An aspect-oriented extension to the Java programming language.</em></span>"</p><p class="simpara"><a class="ulink" href="http://www.eclipse.org/aspectj/"; target="_top">eclipse.org/aspectj</a></p></li><li class="listitem"><p class="simpara"> <span class="strong"><strong>Spring Framework</strong></span> @@ -715,22 +717,22 @@ the CQRS principles.</em></span>"</p><p <span class="strong"><strong>The Fractal Project</strong></span> </p><p class="simpara">"<span class="emphasis"><em>Fractal is a modular, extensible and programming language agnostic component model that can be used to design, implement, deploy and reconfigure systems and applications, from operating systems to middleware platforms and to -graphical user interfaces.</em></span>"</p><p class="simpara"><a class="ulink" href="http://fractal.ow2.org/"; target="_top">fractal.ow2.org</a></p></li></ul></div></div></div></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h2 class="title" style="clear: both"><a id="tutorials"></a>3. Tutorials</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#_overview">3.1. Overview</a></span></dt><dt><span class="section"><a href="#two-minutes-intro">3.2. Qi4j in 2 minutes</a></span></dt><dt><span class="section"><a href="#ten-minutes-intro">3.3. Qi4j in 10 minutes</a></span></dt><dt><span class="section"><a href="#thirty-minutes-intro">3.4. Qi4j in 30 minutes</a></span></dt><dt><span class="section"><a href="#two-hours-intro">3.5. Qi4j in 2 hours</a></span></dt><dt><span class="section"><a href="#howto-depend-on-qi4j">3.6. Depend on Qi4j in your build</a></span></dt><dt><span class="section"><a href="#howto-assemble-application">3.7. Assemble an Application</a></span></dt><dt><span class="section"><a href="#tut-composites">3.8. Transient Composites Tutorial</a></span></dt><dt><span class="section"><a href="#tut-services">3.9. Services Composites Tutorial</a></span></dt><dt><span class="section"><a href="#howto-contextual-fragments">3.10. Use contextual fragments</a></span></dt><dt><span class="section"><a href="#howto-leverage-properties">3.11. Leverage Properties</a></span></dt><dt><span class="section"><a href="#howto-create-constraint">3.12. Create a Constraint</a></span></dt><dt><span class="section"><a href="#howto-create-concern">3.13. Create a Concern</a></span></dt><dt><span class="section"><a href="#howto-create-sideeffect">3.14. Create a SideEffect</a></span></dt><dt><span class="section"><a href="#howto-create-entity">3.15. Create an Entity</a></span></dt><dt><span class="section"><a href="#howto-configure-service">3.16. Configure a Service</ a></span></dt><dt><span class="section"><a href="#howto-invocation-annotation">3.17. Use @Invocation</a></span></dt><dt><span class="section"><a href="#howto-use-io">3.18. Use I/O API</a></span></dt><dt><span class="section"><a href="#build-system">3.19. Build System</a></span></dt><dt><span class="section"><a href="#community-docs">3.20. Writing Qi4j Documentation</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h3 class="title"><a id="_overview"></a>3.1. Overview</h3></div></div></div><div class="tip" style="margin-left: 0; margin-right: 10%;"><table border="0" summary="Tip"><tr><td rowspan="2" align="center" valign="top" width="25"><img alt="[Tip]" src="images/icons/admon/tip.png" /></td><th align="left">Tip</th></tr><tr><td align="left" valign="top"><p>Theses tutorials are based on actual code found in the <code class="literal">tutorials/</code> directory of the -<a class="ulink" href="http://qi4j.org/downloads.html"; target="_top">Qi4j SDK sources</a>. You should start your favorite editor and find the code related to -this tutorial, run it and play with it.</p></td></tr></table></div><p>In this section you will find a comprehensive set of tutorials about Composite Oriented Programming using Qi4j.</p><div class="section"><div class="titlepage"><div><p xmlns="" class="returntotop"><a href="#idm9305972064">Return to top</a></p><div><h4 class="title"><a id="tutorials-intro"></a>Qi4j in 2 hours 42 minutes</h4></div></div></div><p>This quite long introduction to Qi4j will start by brushing up an overview of the problems Qi4j solve, teach you what
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