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Personal opinions and lessons learnt after teaching software engineering and model-driven engineering at different levels, places and environments
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Educating in MDE
Jordi Cabothttp://modeling-languages.com
INRIA & École des Mines de Nantes,
Educating in MDE
Shouldn’t MDE also change the way we teach Software Engineering
in CS degrees?
Model-driven engineering (MDE) is changing the way software
systems are developed, operated and evolved.
Mixing personal opinions and lessons learnt during the last years
teaching SE and MDE in different places, levels and environments
No magical recipes but, hopefully, some useful ideas & discussions
Before we start: Context
Joint team between INRIA & Ecole des Mines de Nantes (EMN)
≈10 members
Research focus on:– MDE core technologies
• metamodeling, MT, MaaS, model management, virtual models…
– MDE applications• reverse engineering, tool interoperability, IS cartography,…
Commitment to Eclipse open-source projects: – ATL, MoDisco, EMF Facet, AMW, AM3, TCS
Strong links with several software development companies
Participation in both national and international research projects
AtlanMod
Nantes
Paris
Nantes is a city in Western France,
with 750,000 inhabitants in the metropolitan area.
Nantes is the most important city
of Brittanyand the 6th town
in France.
850 engineering students
115 doctoral students
125 permanent faculty members + 250 part-time teaching staff
5 research departments
10 specializations (all students get an Engineer Diploma – 2 CS-related specializations)
150 graduates per year
EMN (let´s look at the numbers)
Low number of students. Good Rate students/faculty.
Lots of support for teaching innovation
Emphasis on Technology Transfer
GOOD ENVIRONMENT FOR TEACHING MDE
Model-Driven Engineering
What is MDE?
UML
Code-Generation
DSLs
Model-driven Rev. Eng
Metamodel
M2M
OCL
M2T
Model Evolution
Model-Based Testing
MDD
MDA
Profiles
Multi-modeling
SBVR
BPMN
Model Quality
ATL
QVT
Relationship between MDA/MDD/MDE
MDD = Models as the primary artifact of the development process.
MDA is the OMG's particular vision of MDD
MDE = Models as primary artifacts of any Soft. Eng. activity
Relationship between MDA/MDD/MDE
All model-driven processes are model-based but not the other way
round.
Most MDE techniques are still useful in MBE
Technical Spaces
MDE Grammarware
MOF (metametamode
l)
UML (metamode
l)
ABank.uml
EBNF.g
Java.g
MyProgram.java
Model-Driven Engineering in CS Faculties
Educating in MDE
Shouldn’t MDE also change the way we teach Software Engineering
is taught in CS degrees?
Model-driven engineering (MDE) is changing the way software
systems are developed, operated and evolved.
Is this the case?
MDE is not included in core SE courses
In SE courses, MDE reduced to teaching UML (OCL?) for software specification (and design of centralized systems)
Few faculties have an (optional) course on MDE, sometimes only at the master level
When teaching MDE focus on MDD, e.g. creating a DSL + code-generation from it
Easier to find courses on formal methods for SE !!! (not that I´m saying that FM are not important but …)
Looking at course syllabus in CS degrees (Spain)
Out of topic:
How many courses include version control, bug tracking, tests or
even agile practices?
Existence of MDE courses tightly related to presence of a research group on these topics
Nevertheless, situation much better than a couple of years ago!!
Opinion: Spain is one of the most advanced countries on this aspect (linked to high MDE research activity)
Still time to change the situation (opening of new degrees due to the new regulation)
Looking at course syllabus in CS degrees (II)
When to teach MDE?
MDE concepts should be introduced as part of the core SE courses Everybody has a basic notion of SE It´s clear that MDE is not something apart from (alternative to) SE
Remember: MDE is process agnostic. Fits any dev. process you follow in your SE courses MDE-based Waterfall process MDE-based Agile process (see Agile and Modeling / MDE : friends or foes?) …
When to teach MDE?
Introduction of MDE teaching in three different steps
1. Make sure all SE courses are model-based (some SE courses are more about programming than modeling)
2. Transform (some of) them in model-driven
3. Provide one full MDE course to Show other MDE application scenarios (beyond forward
engineering) Introduce other MDE techniques (e.g. DSLs, model management,
…)
Next we will see what contents include in each scenario
What to teach?
But first: when to teach MDE = When to teach SE.
When to teach Soft. Engineering ?
Soft. Eng. is not taught in the same order!
Students first learn how to program (and design DBs) and then learn
that these programs should be part of “something” called SE
Example (UOC – Open University of Catalonia)
When to teach Soft. Engineering ?
Fundamentos Programación
Programación OO
Estructura de la Información
Bases de Datos I
Bases de Datos II
Sist. Gestión Bases de Datos
Modelos Multidim. y Almacenes de Datos
Ing. Software Estructurado
Ing. Software
Gestión organizaciones y proyectos inf.
Técnicas de Desarrollo Softwqre
Ing. Software OO
Proceso de Ing. Software
Ing. Software componentes y
sistemas distribuidos
Interacción Humano-
Ordenador
Programación Bases de Datos Ingeniería del Software Gestión de la Ingeniería del Software
UML (class diagrams) first introduced in Programming then again in BD
and then again in SE!
Domain modeling seen twice: in BD and in SE
No conceptual link between SE and Programming and BD subjects
We tried to reverse the order (first specification and then programming) but had to reach a consensus
When to teach Soft. Engineering ?
First we introduce SE principles (like lifecycles)
Then we explain in parallel: specification, introduction to programming and introduction to databases.
Once we know the “final implementation platforms” (e.g. Java + RDB) we can explain the principles of the design process
A different course teaches the design process specific to each platform
When to teach SE?
Interdisciplinary: professors from different areas must reach an agreement
Too many course dependencies prevented us from being more ambitious
More info: ¿Podemos darle la vuelta a la enseñanza del desarrollo
del Software? J. M.Marco-Simo et al. Novática 193
What to teach?
What to teach?1. Make your SE courses model-based
Usually SE core courses focus on the specification and design of centralized (or C/S) systems
Final technology platform: a OO program + a RDB as a persistence layer
These courses are already (UML) model-based: use cases, class, sequence diagrams,…
But this is not the case with advanced SE courses on distributed and component-based systems Complex technology platforms (JEE, .NET) Not obvious how to model those systems
Model-based courses
We’ll see an example of transforming a DSE course from
programming-only to model-based
For more info: From Programming to Modeling
Our experience with a Distributed Software Engineering Course.
Cabot et al. ICSE’08 Ed. Sym
Original contents. Focused on teaching distributed technologies
M1 – Distributed Software Distributed environments Distributed object platforms: CORBA, RMI, DCOM
M2 – Component-based Software The components model UML for component-based systems specification
M3 – EJB: Distributed components (>50% of the time) Introduction to the J2EE platform Servlets and JSP The EJB architecture JEE beans: Entity, Session and Message beans Transactions and JEE
From programming to modeling in a Distributed SE course
Problems with this Distributed SE course
This view impairs the students’ ability to develop complex systems that require a more abstract view
Contents quickly became outdated (DCOM?, RMI?)
No methodological aspects about the analysis/design of distributed software systems
No software architecture concepts
No distinction between platform-independent and platform-specific concepts
– Students tend to believe that the acquired knowledge is only useful for the J2EE platform
New course: educational objectives
To relate the DSE field with contents of previous subjects on SE
To combine a practical approach with a conceptual frame that makes it independent of the technology
– A DSE course should especially emphasize its underlying principles
– Students should still learn how to program with a distributed and component-based technology platform (e.g. JEE)
– The course should highlight the similarities among the different technologies and motivate critical attitudes
To use well-established models and notations (e.g. international standards) for the design and development of distributed applications
To teach how to select, evaluate and adapt different approaches, methods and architectural styles
New course: global structure (I)
A system specification is defined as a set of independent viewpoints, each one of these viewpoints focuses on concrete aspects of the system
The Reference Model for Open Distributed Processing (RM-ODP) is used as a framework. Modeling with UML
Link with previous SE courses
New course: global structure (II)
All views have been defined at the PIM level (including the definition of system components and their logical distribution) -> Reusability
Then, adaptation to JEE as example platform:
The main concepts and technologies of J2EE are introduced.
An UML profile for J2EE is explained
Transformations between PIMs and J2EE-specific PSMs and between PSMs and code are shown (but not formalized with any transf. lang)
[30] From module 2 …From module 2 … … … to module 4to module 4
New course: lessons learnt and results
Better learning experience:– It is easier to understand the different aspects that should be
considered in the design of distributed systems– The students have now a broader understanding of the different
concepts and mechanisms of commercial component platforms– Formal polls reveal that the overall student satisfaction has not
changed (even slightly increased)
But…– More contents than before ( failure rate has increased 10% )
All the programming part plus the new “modeling” concerns Ideally we should split the course in two
– Broad set of previous knowledge requiredDBs, Java, UML 2.x, SE…
– (Lab) Technical assistance highly recommended– Teachers need strong skills in both SE, MDD and JEE
It is difficult to find consultants with a suitable profile to teach this course
What to teach?2. A Model-driven SE course
No matter how trendy are DSLs (Domain-Specific Languages), UML is still by far the most important modeling language nowadays …with the permission of BPMN??
UML should still be the basic notation for SE courses. If there´s enough time, a small DSL for a specific system view (e.g. graphical interface) would be great
Profiles should also be part of the UML content in the SE courses Don’t reinvent the wheel vs Don´t push profiles too much
Important: Concrete syntax vs Abstract syntax vs Semantics
Don’t even think about dropping UML
Students should learn that textual modeling is also possible
Not always graphical syntaxes are the best option (e.g. defining behaviour; easier version control).
Textual UML
<img src="http://yuml.me/diagram/scruffy/class/[Customer]->[Billing Address]" >
yUML
TextUML
It´s very important to teach Object Constraint Language. Many applications: Precise specification of software systems Patterns in transformations and model queries Definition of new DSLs …
Importance of Teaching OCL
MachineConveyor
Piece
1*
*
om ic
*+ capacity: int
im
*
oc
*
piece
Integrity constraints
context Conveyor inv: self.piece->size() self.capacity
OCL is not that difficult!!! - Test with students: Most of them were
able to guess without training the meaning of some OCL expr
Best way to teach OCL? Introducing it together with UML during the specification of software systems (less abstract than other scenarios) Invariants Pre and postconditions
Use a UML tool with, at least, an OCL parser (many tools store OCL constraints as simple strings)
Show the effect of those OCL expressions in the code (there are tools for automating this) If-then-else expressions in Java methods Triggers in SQL
Object Constraint Language (II)
If it is not too much to ask make sure they understand the
efficiency issues involved in the evaluation of OCL (Incremental
OCL – Cabot & Teniente )
… but the best tool you can use to teach OCL is the USE tool (model animation tool: define your scenarios and validate your constraints)
Object Constraint Language (III)
MOVA is a
similar tool
MDE SE Course: I’d be happy if they learn…
MeetingInPreparation
Meeting
idstartingDateendingDate
Participant
name
Organizes*
-initiator1
Participates *1..*
<<table>>Participant
-name : varchar<<PK>>-id_Participant : integer
<<table>>Meeting
<<PK>>-id_Meeting : integer-startingDate : varchar-endingDate : date-inPreparation : boolean
<<FK>>
{FK columns = fk_Participantid_Participant , PK columns = id_Participant }
Organizes
PIM
PSM
M2M
CREATE TABLE Participant {Name Varchar2(20) PRIMARY KEY…}
M2T
More than an MDE SE course -> An MDD SE course
Need time to teach other SE concepts (from software processes to design patterns)
To help, we may work with already provided Java and SQL simplified metamodels and partially defined transformations
At this point, the important thing is that they see how things could be done, not so much that they actually do them.
MDE SE Course: Being realistic (time constraints)
IMHO, this should be included in any SE course. Trickier than it seems (and far beyond simple conformance)
If code is generated from models -> quality of code = quality of models
Again, goal: realize that this aspect must also be considered
Quality of models
Not Satisfiable!!
Ex2. Ask your students to model a class person and the recursive relationship isParentOf. How many parents does a
person have?
What to teach?3. A Full MDE course
This section is based on the MDE diploma: 1st full postgraduate program on MDE 1 year duration
Also, as part of a recently granted Leonardo Da Vinci project, we will Adapt the syllabus to different scenarios With focus on Web Engineering as application domain (M.
Brambilla - Politecnico di Milano partner)
Scenarios we will consider: Separate module in a SE course Full course undergrad/grad level Full master Professional course/seminar
A full MDE course
I’ll now present the MDE diploma. Build your MDE course taking a
subset of the MDE diploma modules (depending on your focus)
At least include the creation of a DSL (and its editor)
http://www.mines-nantes.fr/fr/Formations/Formation-specialisee/MDE
The goal of the MDE Diploma is to train engineers to manage complex projects in various IT fields with the latest cutting-edge modeling technologies
6 month full-time courses at the EMN + 6 month internship in a company developing a MDE project
More than 20 invited lecturers
1st edition to finish February 2011. 2nd to start September 2011
Contents include social and management aspects of MDE
The MDE diploma
The MDE diploma: M1
Module 1: Current Software Development Practices (60h)
Software Modeling with current standards: UML, OCL, overview of other standards (MDA, SPEM,…)
Using an Integrated Development Environment: Eclipse EMF, GMF,…
Free and Open Source Software Development
The MDE diploma: M2
Module 2: Automatic Model Processing (60h)
Metamodel design Model-to-model Transformation with ATL Definition of Complex Transformations (HOTs, MT chains) Alternative Transformation Languages (GT and QVT)
The MDE diploma: M3
Module 3: Managing Complex Scenarios (60h)
Model Management repositories, versioning/evolution relating models: weaving models for matching and
traceability…) Integration of Heterogeneous Technologies
Technical spaces Textual syntaxes: TCS, Xtext, MPS MDE and ontologies
The MDE diploma: M4
Module 4: Applications to Information Systems (60h)
Data Engineering Web Engineering Business Rules Engineering Legacy Reverse Engineering Graphical user interfaces …
The MDE diploma: M5
Module 5: Applications to Critical Systems (60h)
Embedded and Real-Time Systems Process Engineering System Engineering Security Engineering Formal Methods …
The MDE diploma: M6
Module 6:Managing MDE Projects (60h)
MDE and management of technology and innovations MDE and management of information systems Industrial Experience Reports
From 360 hours to 430 (counting only hours in class; includes personal work in class)
Very difficult to find people to talk about management of MDE projects.
It’s nice to have invited lecturers but it’s a huge amount of work (even from a “social” perspective)
Students wanted to have a session with me each week to review what they had learnt and related it with previous lectures due to A lot of one day sessions on a single topic. Few ordering constraints among the modules enforced due to
lecturers travel constraints
Apart from the company internship we had to prepare a small project to be done during the courses to help to put everything together
Lessons learnt
How to teach MDE? (miscellaneous)
Focus on concepts and principles instead of focusing on notations and tools
Learning the UML notation is important but it´s much more important (and difficult) learning how to model
Most students finish their SE courses without being able to draw a proper domain model for a 1-page application domain description!
E.g. knowing how to indicate static properties in UML class diagrams it is a necessary but not sufficient condition to apply this concept in practice
Focus on MDE principles
The Modeling Triangle
And please make sure they understand UML is not a development
method. More people than you think believe this
Partially our fault because we usually teach UML following an
implicit method
Method
Notation Tool
All three elements are important!
Bigger impact than with programming languages (all IDEs compile and run programs the same way)
No best choice: Usability vs completeness (e.g. ternary associations,…) vs Features (code-generation,…) At the UOC : an academic license (free) of MagicDraw. … but projects were delivered in pdf. Students could use any tool
they wanted (no support provided for those tools)
For team work, take a look at new breed of online modeling tools
Important: they must understand the difference between a modeling tool and a drawing tool (e.g. Visio)
Choosing the right tool/s
Beyond UML modeling, the safest solution is go to Eclipse and the tools under the Eclipse Modeling Project (EMF, GMF,…)
Better to create a bundle with what they need
Don't underestimate time for learning how to install and setup the tools Most tools have crappy documentation; you decide how students
should spend their time Outdated manuals may be worse than no manuals at all
Choosing the right tool/s (II)
MaaS (Modeling as a Service) still a long-shot but worth
considering. Imagine combining modeling services from different
providers to create your own MDD process
Learning MDE requires practicing with existing model elements
We need examples of models but also metamodels, model transformations,…
What´s out there? ReMoDD (Repository for Model Driven development) Open Model Initiative OOModels AtlanMod zoo of metamodels (>200) and transformations Database Answers: free library of >600 data models
Lack of MDE repositories
Intellectual property issues -> Models (and not products) are becoming the main assets for companies. Don’t want to share
Many kinds of models and modeling languages
Not only repositories but search engines needed on top of them (AtlanMod working on this right now) Search by type Search by domain
What format ? (image, xmi,…)
Models are not enough. We need the context
MDE repositories (II) – Why nothing better?
Only short-term solution I see? Faculty sharing their class exercises
They may not be real-life examples but perfect for learning (we are
experts on that)
Very easy to solve your PHP problems with Google. Try to do the same with UML
Poor and sparse documentation: Most of it referring only to UML And linked to a specific (commercial) tool
The Modeling Languages portal tries to help here
But again, university courses are probably the best source of comprehensible information. Put them online!!
Check upcoming www.learnMDE.com for educational resources
Lack of documentation
Three final thoughts
Let’s explain the real situation
Modeling will be commonplace in 3 years time – S. Mellor– Thought he is giving the same answer for the last 20 years
Prepare students for what they will find in the real life -> no revolution! evolution!)
… but be optimistic
Pains and gains of software modeling Collective benefit but not for some individuals in the team
Socio-technical congruence: Is the company ready for MDE? Team members can perform the activities required in a MDE
process? Do they have the right skillset? Can they satisfy the new dependencies between them?
Without forgetting the Social Aspects
Adopting MDE is NOT buying a code-generator!!!