Openflexo Pamela

Introduction

Introduction to Pamela

Pamela is an annotation-based Java modelling framework. The strong idea behind this technology is a smooth integration between model and code, without code generation nor externalized model serialization. We aim to avoid separation between model and code to simplify consistency management and avoid round-tripping issues.

Key features of Pamela

• Model/code strong coupling
• No code generation: the 'model' is serialized in the Java code with annotations
• Custom implementations might be redefined by the developer
• All is executed at run-time: Java dynamic binding is overridden
• Support for multiple inheritance in Java
• XML serialization/deserialization
• On the fly meta-model closure computation (powerful management of metamodel fragmentation)
• Integrated notification management
• Embedding management
• Object graph closure computation
• Deletion management
• Clipboard operations (copy, cut, paste) management
• Multi-level undo/redo support
• A graphical editor is also provided in this project, allowing to graphically view and edit Pamela models.

Getting Pamela

There are several way to get Pamela.

OpenFlexo

OpenFlexo make instensive use of Pamela. If you're using OpenFlexo you have access to Pamela.

Maven

Pamela is built using maven (soon it will use Gradle) and publish it's artifacts to the OpenFlexo maven repository. In order to use Pamela in your maven project, add the repository adding the following in the pom.xml:

<repositories>
    <repository>
        <id>openflexo-release</id>
        <name>openflexo-release</name>
        <url>https://maven.openflexo.org/artifactory/openflexo-release/</url>
    </repository>
</repositories>

Add also the dependency to the pamela-core artifact:

<dependency>
  <groupId>org.openflexo</groupId>
  <artifactId>pamela-core</artifactId>
  <version>RELEASE</version>
</dependency>

Gradle

Even if Pamela is build using maven, it's easy to use it from Gradle. The Pamela artifact are publish in the OpenFlexo maven repository. In order to use Pamela in your gradle project, add the repository adding the following in the build.gradle:

maven {
    url "https://maven.openflexo.org/artifactory/openflexo-release/"
}

Add also the dependency to the pamela-core artifact:

compile group: 'org.openflexo', name: 'pamela-core', version: '1.3-RC1'

Direct download

Pamela can be directly downloaded from the OpenFlexo maven repository along with it dependencies:

• org.openflexo:pamela-core:1.3-RC1,
• org.openflexo:connie-core:1.3-RC1,
• org.openflexo:flexoutils:1.3-RC1,
• org.openflexo:tools-configuration:0.4-RC1.
• com.google.guava:guava:18.0,
• org.apache.commons:commons-lang3:3.1,
• org.javassist:javassist:3.18.0-GA,

TODO

Build it your self

In order to get the most up to date code you can build Pamela yourself.

Prerequisite

• git.
• Java JDK 7
• Maven

Building Pamela is easy, follow these steps:

TODO

Your first model

To build your first model, you only have to defined the interface, Pamela does the implementation for you. Just write:

@ModelEntity
interface Person {
    String NAME = "name";

    @Getter(NAME)
    String getName();

    @Setter(NAME)
    void setName(String name);
}

Pamela will build a class that implements the getName getter and the setName setter. The getter is really simple, it returns the stored property name. The setter is much more evolved sine it:

• sets the value,
• notify the value change (if the new value is actually different) and
• saves the change to an undo manager.

The setter will also handle the opposite property when needed as we see later on.

Gotcha

Since Pamela constructs it's own implementation of the interface, you can also build your own.

public class PersonImpl {
    private String name;
    
    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
}

But this implementation is really basic and doesn't provide advanced capabilities as Pamela does.

Reference documentation

The javadoc for Pamela can be found here.

Frequently Asked Questions

Class cannot access its superinterface

If you encounter an Exception like the following:

Exception in thread "main" java.lang.RuntimeException: by java.lang.IllegalAccessError: class org.javassist.tmp.java.lang.Object_$$_jvst41b_0 cannot access its superinterface MyClass

This means that the interface MyClass isn't accessible, it must be public.

How to check if my model is sound

Pamela offer high level model definitions but it does so by tricking the Java compiler using abstract constructions. You can easily check if your model is sound with a simple test:

ModelFactory factory = new ModelFactory(MyRootModelClass.class);
factory.checkMethodImplementations();