PRMS Report

Abstract

• This report developes the idea of a visual graphical editor for Epsilon and the process of developing it.
• A fully working epsilon workflow builder and visualizer is also presented that helps users to compose Epsilon workflows and construct visual representations from textual ones.

Statement of Ethics

• Informal user survey for requirements.
• Formal user survey to evaluate the tool ?

Introduction

Motivation

• Why EWE ? What is the need ?
• Workflow inherently visual - flow of order of tasks.
• e.g. BPM tools all provide editors.
• MDE is essentially a sequence of steps from start to finish.
• Other model management languages, frameworks tools provide it as well. (Atlas, OpenAW, etc)
• Therefore Epsilon, needs one too.

Method

• Documents the process of building such a tool using MDE techniques and Epsilon itself.

Literature Review

• Introduce ALL concepts and technologies that are critical to understanding the tool.
• Model driven engineering - tasks involved. Tasks constitute a workflow.
• How does Epsilon handle it ? Internal architecture of Epsilon Workflow.
• ANT, Java Modules, Eclipse Launch configuration, Working outside Eclipse.
• Provide a general introduction to build management, concept of dependency, task ordering, conditional ordering, task failures, transactions.
• How ANT provides some of these features as a build tool. How Epsilon uses ANT as an architecture - quote from Epsilon ANT paper.
• Introduce idea of domain modeling. Separate the concern of design and architecture. This is the CORE idea.
• Eclipse EMF technologies. How EMF supports Domain Modeling. Give a simple Library example.
  • Library domain is expressed. An Editor for the domain is generated - but uses unique architecture. e.g. Adapter, Factory and Command patterns - which WE never specified while modeling the domain.
• Make sure this concept is well understood. MDE in general and how EMF tools support MDE with practical examples.
• Eclipse graphical technologies GEF -> SWT, JFace.
• Eclipse GMF as a bridge between GEF and EMF.
• How GMF is Model based and Generative
• How it fits well for Epsilon since both are based on EMF.
• Introduction to EuGENia.

Requirements

• Initial project description
• Asking Epsilon users to comment on forum
• Discussion with Supervisor
• Self proposed requirements

Design

• Eclipse vs NonEclipse
• EMF in built editor vs (GMF/Graphiti)
• GMF vs Graphiti
• GMF - EuGENia support (Generate GMF vs manual GMF model creation), in house expertise with GMF models, EuGENia authors based in York, customization.
• EuGENia GMF support for EVL and error/warning markers.

ECore metamodel design

• Represeting ANT concepts as GMF nodes for e.g. Project, Target.
• Using concept of depends and follows.
• Accurate modeling of ANT structure - allows operations to be performed at the higher Task level as opposed to lower levels - such as EOLTask etc.

Scripting design choices

• Using Java vs using Epsilon languages
• Epsilon :- reflective features. Easy model navigation.
• Using EGL:
  • Protected regions: Merge engine
  • XML Formatter
  • Full reflective support.

Editor Design

• Task to GMF node mapping design choices (Which elements in the metamodel should be visualized)
• Compartments vs Property views - Too boxy. So rejected.
• Property Sheet
• Property Sheet implementation choices : Custom SWT code (rejected/knowledge of SWT - Time constraints: Used by Ecore editor)
• EEF as the choice.
• EEF: new technology, never been integrated with GMF before.
• Challenges in customising EEF - Poorly documented code base.