Model-driven engineering (MDE) is a software development methodology which focuses on creating and exploiting domain models (that is, abstract representations of the knowledge and activities that govern a particular application domain), rather than on the computing (or algorithmic) concepts.
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[quote,me]
And also focus on creating modeling languages to represent these domain models.
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== Models as the central artifact of software development
** Environment Integration, Adaptation, (Software and GUI), Flexibility (notion of product lines)
* Increasing importance of non-functional properties:
** Distributed systems, parallel and asynchronous
** Security
== Modern Software Problems (2/2)
.Increasing complexity of infrastructures:
* Operating system APIs, language libraries, application frameworks
.Increasing importance of quality of services:
* reliability, latency, performance
== Increasing complexity (1/2)
* The control software to run a U.S. military drone uses 3.5 million lines of code.
* A Boeing 787 has 6.5 million lines behind its avionics and online support systems.
* Google Chrome (browser) runs on 6.7 million lines of code (upper estimate).
* A Chevy Volt uses 10 million lines.
* The Android operating system runs on 12-15 million lines.
== Increasing complexity (2/2)
* The Large Hadron Collider uses 50 million lines.
* Not including backend code, Facebook runs on 62 million lines of code.
* With the advent of sophisticated, cloud-connected infotainment systems, the car software in a modern vehicle apparently uses 100 million lines of code. This is according to Wired magazine.
* All Google services combine for a whopping 2 billion lines.
* Shortage of programmers even for simple applications: Mobile apps, Web, etc.
* Build programs that generate/configure programs:
** Put problem-solving capabilities into the hands of non-IT professionals
** Users can more quickly and easily create business apps that help them do their jobs
* Analysts at Gartner estimate that the low-code market grew 23% in 2020 to reach $11.3 billion, and will grow to $13.8 billion in 2021 and almost $30 billion by 2025
== In short
* Growing complexity of software
* Separation of concerns
* Separation of professions
* Requirement diversity
* Platform diversity
* Continuous evolution
[.block]
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* Is source code the correct level of abstraction?
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== Agenda
* Definition
* Context
* *Software Modeling*
* Meta-modeling
* Conclusion
== Defintion
[quote]
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A Model is a simplified or partial representation of reality, defined in order to accomplish a task or to reach an agreement
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== Why?
[quote]
Modeling, in the broadest sense, is the cost-effective use of something in place of something else for some cognitive purpose. It allows us to use something that is simpler, safer or cheaper than reality instead of reality for some purpose.
[quote,Jeff Rothenberg]
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A model represents reality for the given purpose; the model is an abstraction of reality in the sense that it cannot represent all aspects of reality. This allows us to deal with the world in a simplified manner, avoiding the complexity, danger and irreversibility of reality.
* Description of a real phenomenon (descriptive models).
== Models in Traditional Engineering
.Example by Brian Selic
image::engineering.png[align=center,width=1000px]
* A reduced representation of some system that highlights the properties of interest from a given viewpoint.
* Description of something in order to build it (prescriptive models).
== Properties of a Useful Model
[Selic]
* *Abstract*: emphasize important aspects while removing irrelevant ones.
* *Understandable*: expressed in a form that is readily understood by observers.
* *Accurate*: Faithfully represents the modeled system
* *Predictive*: Can be used to answer questions about the modeled system
* *Inexpensive*: Much cheaper to construct and study than the modeled system
[.block]
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_To be useful, engineering models must satisfy all of these characteristics_!
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== Models in Software Engineering
[quote, Selic]
Software has the rare property that it allows us to directly evolve models into full-fledged implementations without changing the engineering medium, tools, or methods!
* This ensures perfect accuracy of software models; since the model and the system that it models are the same thing
* The model evolves into the system it was modeling
== Entity-Relationship Model
.[Chen ’76]
image::entity-relationship.png[align=center]
* Database modeling method, used to produce a type of conceptual schema or semantic data model of a system, often a relational database, and its requirements in a top-down fashion.
== Data-Flow Diagrams
.[Constantine & Yourdon ’75]
image::dfd-example.png[align=center,width=800px]
* Graphical representation of a flow of data through an information system.
== Petri Nets
Early seventies
.Mathematical modeling language for the description of distributed systems
image::petri.gif[align=center]
== State Diagrams [Booth ’67]
image::state-machine.svg[align=center]
* Describes the behavior of a system in terms of states.
== UML [Los 3 amigos ’96]
.One model, 4 dimensions, multiple views:
. Static Aspect (Who?)
** Class, Component, Package and Object Diagrams
. User view (What?)
** Use Case Diagrams
. Dynamic Aspects (When?)
** Interaction diagram (Sequence, Collaboration), State and Activity Diagrams
