PROfessional network of Master’s degrees in Informatics as a Second Competence – PROMIS
(544319-TEMPUS-1-2013-1-FR-TEMPUS-JPCR)
ARCHITECTURAL SEPARATION
(MVC, ARCH MODEL,
SEEHEIM).
Bakaev Ilkhom
Today’s Plan
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1. Architecture separation
2. Design Patterns
3. Why MVC
4. What is MVC
5. What is ARCH model
6. What is SHEEHEIM model
PROfessional network of Master’s degrees in Informatics as a Second Competence –
PROMIS (544319-TEMPUS-1-2013-1-FR-TEMPUS-JPCR)
Architecture separation
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The architecture of a computer system is a set of
structures which include: components, the outside visible
properties of these components and the relations
between them.
The aim of architecture models is to supply a pattern
for the design and the realization of the user interface.
They decompose the HMI (Human-Machine Interface)
into modules and define appropriate roles for each
module. These roles contribute towards the correct
execution of the system.
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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Architecture separation
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Several architecture models have been put forward by
researchers over the past twenty years. Three main
types of architecture can be distinguished in the
resulting research literature:
The Language Model (the precursor): presents an
analogy between the human dialogue and the humanmachine interaction.
Functional models: they bring the software and the
interaction together into functional levels.
Agent-based Models: they organize an interactive
system into a set of reactions and stimulus.
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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Architecture separation
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These architecture models recommend the same
principle, based on the separation between the system
(application) and the human-machine interface.
Therefore, the architecture has to separate application
and interface, to define a distribution of the interface
services, and to define an exchange protocol [18].
The advantage of separating the interface: it facilitates
modifications which can be made to the interface
without changing the application.
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The Language model
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The Language model was proposed by [14]. This
model decomposes the application and the humanmachine interface in the same way as a language.
In spite of the fact that this model defines four
levels of abstraction, it also has some drawbacks.
 Priority
is given to the shape of the information
 The level of abstraction of the protocols of
communication between components is not sufficiently
clear [6].
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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The Language model
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The basic principles of the Language model have
been used by many researchers, and have
influenced the definition of several generic models.
The most well-known are functional models.
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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Functional models
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The functional architecture models provide a
separation between the application and the
interface. The Seeheim model is the most widely
known.
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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Seeheim Reference Architecture
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The Seeheim reference architecture applies part whole decomposition to the monolithic reference
architecture.
Presentation
Dialogue
Application
Improved Seeheim
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Uses compression to improve performance problems
Presentation
Dialogue
Application
Strengths of Seeheim Reference
Architecture
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A separate presentation function supports
portability and modifiability.
A separate application layer allows modification of
function without affecting the user interface.
A separate dialogue allows modifications to user
interaction without rewriting the presentation.
Weaknesses of Seeheim Reference
Architecture
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Many modifications affect all three functions.
There are performance problems with sophisticated
semantic feedback (which result in the need for
compression).
Use of the architecture leads to separate notations
for dialogue, presentation, and application layer;
this is cumbersome.
Unit Operations and HCI Reference
Architectures
Seeheim
Monolithic
architecture
abstraction
part-whole
Arch/
Slinky
part-whole
MVC
is-a
PAC
PAC/
AMODEUS
The Seeheim model
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The Seeheim model (Cf. figure 1) was
proposed in 1983 by Pfaff [27].
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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The Seeheim model
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This model works as follows: the presentation
performs a lexical analysis in order to translate
the statements of the user into computer language.
The dialogue controller provides a syntactic analysis
of the interaction language. It also manages interaction
between the presentation and the application.
The final module makes it possible to translate the
statement into specification language in order to reach
the application
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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The Seeheim model
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The Seeheim model has some drawbacks such as
the separation between the dialogue controller
component and the other components, which is not
always true in reality.
Indeed, the application interface can use
semantic information, which makes it possible to
control feed-backs for example, to generate
default values or to check errors
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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The Arch model
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The Arch model [1] is a revision of the
Seeheim model. It defines a functional breakdown
of the interface into five different elements (Cf.
Figure 2).
Both the presentation component and the interaction
component are a decomposition of the presentation
of the Seeheim model. The interaction component
manages the physical interactions with the user.
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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The Arch model
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The presentation component supplies a set of
presentation objects which are independent of any
toolkit.
The functional kernel carries out the domain
concepts. The domain adapter is used for
adjusting the differences in the modelling of
conceptual objects between the functional kernel
and the dialogue controller.
Note that the Arch model is limited in that it is
centralized.
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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The Arch model
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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The Arch model
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Seeheim and Arch provide canonical functional
structures with big gain.
These models are useful as a structural
framework for a design or a rough analysis of
the functional decomposition of an interactive
system.
Multi-agent reference models aim at a finer
functional breakdown.
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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Agent based model
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Agent-based models are generally based on a
modular decomposition of the elements of the
interface (like functional models with levels of
abstraction) as well as on a reorganization of the
location of features and of data and the hierarchy
between each entity.
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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Agent based model
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We shall not detail the notion of agent, but retain
the following definition for the term agent:
"An agent acts according to a set of information
received and perceived from its environment and
according to the goal which it is pursuing".
PROfessional network of Master’s degrees in Informatics as a Second Competence –
PROMIS (544319-TEMPUS-1-2013-1-FR-TEMPUS-JPCR)
WHY MVC?
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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Overview
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1. Design Patterns
2. Why MVC
3. What is MVC
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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PROBLEM
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Problem - Without the separation of concerns a
developer has to rely and wait for the feeds of
others to complete his tasks. Productivity --
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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SOLUTION
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Solution - With separation of concerns by MVC, he
can build applications faster, Unit test them easily
without any involvement of other developers.
Productivity ++
PROfessional network of Master’s degrees in Informatics as a Second Competence –
PROMIS (544319-TEMPUS-1-2013-1-FR-TEMPUS-JPCR)
MVC
Pattern?
Architecture?
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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Framework?
PATTERN
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“ Each pattern is a three-part rule, which:
 expresses
a relation between a certain context (design
context),
 a certain system of forces which occurs repeatedly in
that context (recurring design problem),
 and a certain software configuration which allows these
forces to resolve themselves (solution).“
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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ARCHITECTURAL PATTERN:
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Fundamental structural organization for software
systems.
Architectural patterns are high-level strategies that
concerns large-scale components, the global
properties and mechanisms of a system.
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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ARCHITECTURAL PATTERN:
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“At the highest level, there are the architecture
patterns that define the overall shape and structure
of software applications.
Down a level is the architecture that is specifically
related to the purpose of the software application.
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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ARCHITECTURAL PATTERN:
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Yet another level down resides the architecture of
the modules and their interconnections. This is the
domain of design patterns, packages, components,
and classes.”
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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FRAMEWORK:
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A software framework is a universal, reusable
software platform used to develop applications,
products and solutions.
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MVC
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In the MVC paradigm, the user input, the modeling
of the external world, and the visual feedback to
the user are explicitly separated and handled by
three types of objects, each specialized for its task.
A software framework is a universal, reusable
software platform used to develop applications,
products and solutions.
PROfessional network of Master’s degrees in Informatics as a Second Competence –
PROMIS (544319-TEMPUS-1-2013-1-FR-TEMPUS-JPCR)
MVC
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Model
View
Controller
Model
View
Controller
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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Model
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The model is responsible for managing the data of
the application.
It responds to the request from the view and it also
responds to instructions from the controller to
update itself
It is the lowest level of the pattern which is
responsible for maintaining data.
The Model represents the application core (for
instance a list of database records).
It is also called the domain layer
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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View
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The View displays the data (the database records).
A view requests information from the model, that it
needs to generate an output representation.
It presents data in a particular format like JSP, ASP,
PHP.
MVC is often seen in web applications, where the
view is the HTML page.
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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Controller
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The Controller is the part of the application that
handles user interaction.
Typically controllers read data from a view, control
user input, and send input data to the model.
It handles the input, typically user actions and may
invoke changes on the model and view.
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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Working of MVC in web application
PROfessional network of Master’s degrees in Informatics as a Second Competence –
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Questions
39
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Do controllers have a user interface?
Does a view allow user input?
Can a view send messages to the model?
Can a view send messages to the controller?
Can you have more than one view?
Can you more than one model?
Can you more than one controller?
Is a controller just one file? A View?, A Model?
Should the view UI be separate from the controller
interface?