Roma introduction and concepts

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Roma introduction and concepts

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Romulus project ended, new modules moved to the Roma SVN repository

After more than 2 years of good work, sharing of ideas, cooperation and, of course, development the Romulus project reaches the end. The Romulus project brought a lot of modules in the Roma Framework project:

• View-Janiculum as new View Aspect based on HTML and CSS2. It uses FreeMarker to render single components
  
• Project-Portlet, Session-Portlet and Wizard-Portlet, to deploy Roma Applications as JSR-168 portlets (but there is also some extension for Liferay, our partner)
  
• Semantic Jena, to export your domain in RDF just annotating it
• Mashup-MyCocktail, to create mashup by using the MyCocktail Open Source product (built under Romulus)

Starting from today these modules will be available and supported directly from the Roma community and therefore have been moved in the Roma Framework Subversion repository.

Soon the new version 2.2 that include Janiculum as default View Aspect by replacing the View-Echo2 module (after 4 years!). View-Echo2 will rest in the repository but all the new development on the Web UI will be concentrated only to the Janiculum module.

To switch your project to janiculum just download it and add as module. The Janiculum wizard will do the rest. All your application will work but stylesheets that in Janiculum are CSS and not anymore custom XML.

Released TevereFlow, the first workflow engine with a Web Editor

Starting from December 22nd 2009 is available the new version of TevereFlow. Tevere Flow is a light-weight Workflow engine built using the Java® technology. Just download it and create your process using the Web interface. You can use Tevere as embedded or as external engine by using the provided Web Services API.

Tevere was built using Roma Framework under the Romulus consortium an it's currently used in several production systems.

Main features:

• Open Source Apache 2.0 license
• Web User Interface using the Ajax technology
• Stand-alone application: just download and start it
• Fully Transactional supporting any RDBMS or db4o ODBMS
• Set of built-in commands available (email, web service invocation, etc.)
• Auto-resume of failure activities
• User and profile management
• Activities can be written in Java or using any supported scripting language such as Javascript and Ruby
• Integration via Java APIs or WebService

Online a new demo of an application developed with Roma Meta Framework: Whiz! Whiz is the smaller Social Network never built. You can try it online or download it in local and change the sources as you want.

http://www.romaframework.org/demo.html

Romulus FREE workshop in Italy: the new way to build Web Applications

The Romulus consortium is organizing a new FREE event on December, 17th 2009: "Romulus FREE workshop: the new way to build Web Applications". The event is hosted in Rome, Italy under the form of a technical workshop. Most of the talks will be in the Italian language. If you're interested to have the same workshop in your city please contact romaframework -at- assetdata.it.

Location: http://www.h10hotels.com/ita/hotels-roma/h10-roma-citta.php

Draft agenda:

• 9.30 - 9.45: Presentation of the Romulus consortium [Talk in italian]
• 9.45 - 10.45: Introduction to Roma Meta Framework [Talk in italian]
• 10.45 - 11.00: Coffe break
• 11.00 - 13.00: Hands-on session: creation of a Twitter-like application from ground using the DDD approach and Roma Meta Framework. In this session the Asset Data's guys will help the attendees on installation and/or compilation problems. All the attendees with a notebook can download and install all the necessary to begin with Roma and follow the speaker step-by-step [Talk in italian]
• 13.00 - 13.45: Lunch with sandwich
• 13.45 - 14.15: Create automatic testing for the application [Talk in english by Universidad Politécnica de Madrid?]
• 14.15 - 15.00: Mashup of Social network's data with Google Maps and Flickr [Talk in english by Gesfor company?]
• 15.00 - 15.30: Exporting data in Semantic format (Semantic Web). Make the information accessible from a semantic search engine to execute queries like: "give me all the people living in Rome with at least 3 friends living outside his city" [Talk in english by Digital Enterprise Research Institute of Ireland]
• 15.30 - 15.45: Coffe break
• 15.45 - 16.15: Exporting of services and its usage inside a ESB (Atom and Web Services?) [Talk in italian by Imola Informatica]
• 16.15 - 16.45: Vertical demonstrators [Talk in english]
• 16.45 - 17.00: Conclusions [Talk in italian]

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New Hook Aspect to use AOP concepts inside Roma Framework

Hook Aspect

The Hook Aspect aims to write listeners of POJO events in simple way. The Hook Aspect allows the developer to extend an existent application in a flash. The Hook Aspect is based on the well known principles of Aspect Oriented Programming, AOP by now. The AOP supports the Object oriented paradigm. The two approaches can be used together to get the best of both.

You can hook any action of any POJO at runtime as well as read/write of any fields.

Using the Hook Aspect you can change and customize your application behaviour in a non-invasive mode.

Scope

Each hook belong to a scope. Scope can be:

• SESSION, means that all the registered POJOs that are part of the current User Session will be waked up when the event is raised

• APPLICATION, means that the POJOs are components declared into the IoC container (Spring IoC).

Using the scope APPLICATION you must assure that the POJO loaded by Spring IoC use the annotation @CoreClass(loading=EARLY) on top of the class declaration (look at the example below). This is the only way to assure to activate the Roma configuration when the application starts.

Below a table of the hooks available for the action:

@HookAction	Description
onBeforeAction	Invoked just before an action is called
onAroundAction	Invoked in place of the original action
onAfterAction	Invoked just after an action is called
onBeforeFieldRead	Invoked just before a field is read
onAroundFieldRead	Invoked in place of the original read. The action must return the value to return in place of the original
onAfterFieldRead	Invoked just after a field is read
onBeforeFieldWrite	Invoked just before a field is written
onAroundFieldWrite	Invoked in place of the original write. The action must return the value to assign to the field in place of the original
onAfterFieldWrite	Invoked just after a field is written

@HookField	Description
field	Copy the content of the field hooked everytime changes

Change the behaviour at run-time

In this example you need to avoid further login into the application for a while. The classic path would be to change the code or to write a parameter to switch on/off this feature.

Using a hook makes all things much easyer. Please note that the hook hookAroundAction means in-place-of. This action will be called in place of the original one.

ApplicationControl Example

@CoreClass(loading = LOADING_MODE.EARLY)

public class ApplicationControl {

@HookAction(hookAroundAction="CustomLogin.login", scope=HookScope.APPLICATION)

public void hook() {

  // DISABLE THE LOGIN

  System.out.println("Application in mantainance: login disabled");

  RomaFrontend.flow().forward(

         new MessageOk("login", "Login temporary disabled").

         setMessage("Login is temporary disabled, please try in few minutes"),

         "screen:popup:alert");

  }

}

In the same way you can customize strategies, alghoritms, navigation paths all by using the Hook Aspect.

Collect results

This is an example of a simple profiler that record in a Map in memory the times the actions are called.

Remember that to use the scope “application” you need to instantiate the component as singleton by the IoC container (Spring IoC at this time). Add this line at the end of applicationContext.xml file of your application:

<bean id="ProfilerDemo" singleton="true" class="com.orientechnologies.moobilis.server.view.domain.ProfilerDemo" />

And create a class in this way:

ProfilerDemo Example:

import java.util.HashMap;



import org.romaframework.aspect.hook.annotation.HookAction;

import org.romaframework.aspect.hook.annotation.HookScope;



@CoreClass(loading = LOADING_MODE.EARLY)

public class ProfilerDemo {



   protected HashMap<String, Long>    totalTimes = new HashMap<String, Long>();



   @HookAction(hookAfterAction = "*", scope = HookScope.APPLICATION)

   public void profileAllActions() {

       Long times = totalTimes.get("allActions");

       if (times == null)

           times = new Long(0);

       times = times + 1;

       totalTimes.put("allActions", times);

   }



   @HookAction(hookAfterAction = "*Login*", scope = HookScope.APPLICATION)

   public void profileAllLoginActions() {

       Long times = totalTimes.get("loginActions");

       if (times == null)

           times = new Long(0);

       times = times + 1;

       totalTimes.put("loginActions", times);

   }

}

Finally released the "Virtual Objects" in SVN trunk

Roma Framework is strictly based on the POJO Java architecture. Anything is a POJO from the view to the persistence. But in some circumstances it could be better having a lighter way to hide some fields in a form or adding a new action to an existent POJO.

This is the reason because Roma (starting from version 2.0.3) supports the Virtual Objects. Virtual Objects are treated just as real Java Objects but they are declared using a descriptor. Now only XML descriptor is supported but in future it could be planned JSON or other ways.

Virtual Objects, in effects, are declared using the same XML Annotation syntax with minor additions to handle field types, inheritance and other stuff that Roma can't know since the XML descriptor is not backed by a real class file.

Cross language

Virtual object's business logic is written inside the tag using the Scripting Aspect. This means that Virtual Objects are totally decoupled by the Java technology and they can be written in any language supported by the JSR 223.

Hot changes high productivity

Virtual Objects are loaded at run-time and reloaded every time the file is saved. This boost up the productivity since it never requires to restart the JVM!

Indeed changing the signature of a class (add and remove attributes and methods) require always the JVM to restart. This is the reason why the Virtual Objects are strongly suggested to being used to build forms to display.

Web IDE

It's planned for the end of 2009 a powerful graphic editor on the Web to change the virtual objects directly from the running application without the need of an IDE.

Not Just Forms

Even though Virtual Objects makes the difference used in the View Aspect, they can be improve the productivity in any Aspect of Roma. Think for example to a service written entirely in Javascript just creating the XML descriptor and annotating it with the Service Aspect.

Below an example of a Virtual Object that extends the Roma's CustomLogin standard POJO used to make the login. Note that by default the language setted is the Scripting Aspect is JavaScript but you can use any language installed using the JSR 223 implementations.

MyLogin.xml

<?xml version="1.0" encoding="UTF-8" standalone="no"?>

<class xmlns="http://www.romaframework.org/xml/roma" xmlns:xsd="http://www.w3.org/2001/XMLSchema-instance"

xsd:schemaLocation="http://www.romaframework.org/xml/roma http://www.romaframework.org/schema/v2/roma.xsd" extends="CustomLogin">

<aspects>

  <view>

      <form>

          <area name="main" type="grid" size="1">

              <area name="help" />

              <area name="fields" type="grid" size="2" />

              <area name="actions" type="row" />

          </area>

      </form>

  </view>

  <scripting>

      me.field("help", "Please insert your account." );

  </scripting>

</aspects>

<fields>

  <field name="help" type="String">

      <aspects>

          <view render="html" />

      </aspects>

  </field>

  <field name="additionalCode" type="String">

      <aspects>

          <validation required="true" min="5" max="5" />

      </aspects>

  </field>

</fields>

<actions>

  <action name="login">

      <aspects>

          <scripting>if( me.field("additionalCode") == "12345" ) me.parent.login();</scripting>

      </aspects>

  </action>

  <action name="close">

      <aspects>

          <scripting>org.romaframework.frontend.RomaFrontend.view().close(me.pojo);</scripting>

      </aspects>

  </action>

  <action name="standardLogin">

      <aspects>

          <scripting>

          <![CDATA[

              print('Goto standard login...')

              org.romaframework.frontend.RomaFrontend.flow().forward("ProjectLogin")

          ]]>

          </scripting>

      </aspects>

  </action>

</actions>

</class>

In this example the Virtual Object called “MyLogin” makes the following changes to the class CustomLogin that extends:

• Add a new field called “help” defined as a String and displayed as HTML on top of all fields (see area definition)

• Add a new field called “additionalCode” defined as a String. This field define some validation rules: it's mandatory and the length must be of 5 characters

• In the constructor (see the scripting declaration inside the class) the field help is initialized with a welcome message.

• The login action is overridden to check if the virtual field “additionalCode” is equals to “12345”. Only in this case calls the super.login(). Not the use of “me.parent” that returns the super class.

• Add a new action called “close” to close the form. Note the use of “me.pojo” to return the real POJO in Roma.

• Add a new action called “Standard Login” that show the classic Login form.

You can use a Virtual Object such as normal POJO in Roma. To display the Virtual Object just created write:

public void test() {

RomaFrontend.flow().forward(new VObject("MyLogin"), "screen:popup");

}

Or just:

public void test() {

RomaFrontend.flow().forward("MyLogin");

}

The final result is the image on top of this post.

Enjoy!