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Long Tutorial lessons
1
Lesson 1
Creating the First Paradigm and Model
Introduction to Lesson 1
In
this
first
lesson,
you
will
configure
GME
to
allow
the
drawing
of
basic
diagrams
for
a
specific
application
domain.
Later
lessons
will
show
you
how
to
extend the
project with more advanced features.
The
application
domain
throughout
this
tutorial
is
that
of
networking
systems:
routers, networked computers, and other
devices, as well as the connections between
these devices. Your application domain
is probably quite different from this one, but
looking
at
a
specific
domain
as
an
example
is
probably
the
best
way
to
help
you
identify
the
main
steps
of
modeling
and
learn
the
techniques
of
customizing
GME.
There
are
some
sections
that
describe
the
details
of
networking,
and
serve
as
Those sections appear in red
italics
. If you are not familiar with
networking, you may
find them
irrelevant or hard to understand. Feel free to
skim or even skip them, and
focus on
the rest of the tutorial, which deals with the
more practical aspects of GME.
This
tutorial
provides
enough
information
to
give
the
average
user
a
well-
developed
understanding
of
GME,
without
having
to
rely
on
extra
documentation. Of course, to gain a
deeper understanding of GME and to learn all of
its features, you will need to consult
the GME Users Manual as well.
1.1
GME and the
modeling process
GME
is
a
generic,
configurable
modeling
environment.
In
other
words,
the
configuration of GME is not an option;
it is the first step that must be taken before
anything
meaningful
can
be
done
with
it.
The
configuration
process
itself
is
also
a
form of modeling - the
modeling of a modeling process. This is called
metamodeling.
The output of the
metamodeling process is a compiled set of rules,
the paradigm, that
configures GME for a
specific application domain. (GME
是一个通用的
、可配置的
建模环境。换句话说，
GME
的配置不是一个选项，而是用
GME
做任何有意义
的事情之前必须做的第一个步骤。配置过程本身也是一种类型的建模
-
对于建模
处理过程的建模。
这叫做元建模<
/p>
metamodeling
。
元建模过程
的输出是一系列编译
过的规则，范例，它们为特定的应用域配置
GME
。
)
Does
everyone need to
be a metamodeling
expert to use GME? Of course not.
Normally,
only
a
few
people
participate
in
the
metamodeling
process.
By
contrast,
there
are
numerous
users
of
the
configured
environment.
The
users
do
not
need
to
know
much
about
metamodeling;
what
they
see
is
a
graphical
tool
with
editing
capabilities
that
is
already
customized
for
their
domain.
The
main
advantage
of
model-integrated computing is that the
work of the users is guided by the modeling
environment.
This
tutorial
is
written
for
those
who
are
interested
in
metamodeling
and
customization.
The
majority
of
the
tutorial
deals
specifically
with
metamodeling
issues;
examples
of
customized
environments
are
usually
explained
in
much
less
detail.
Remember,
the
metamodeling
environment
itself
is
also
based
on
GME.
So
while acting as a
metamodeler, you are also a user of the customized
environment of
GME, based on its meta-
paradigm. By the time you begin to build models,
you will
have already had plenty of
practice simply by using the metamodeling
environment!
1.1.1
问题说明
Problem specification
The
first
thing
that
a
metamodeling
expert
needs
is
a
specification
(or
at
least
some
vague
idea)
of
the
modeling
application
to
be
implemented.
This
typically
comes in a
natural-language description.
（一个元建模老手需
要的第一件事是一个
要实现的建模应用的说明书或者至少是粗略的想法。
）
As an example, the proposed
network modeling application is
described below:
want
to
create
networking
diagrams.
The
diagrams
will
contain
routers.
Each router has several router-ports.
We also
have hosts
(e.g. servers). We want
to
connect router-ports and hosts to form
networks.
following:
or
[i.e.
we
have
Cisco
and
Linux
routers].
Ports
are
identified
by
portname,
IP
address,
speed
(in
kbps),
and
type
(which is either
are
identified
by
name
and
address
(for
now,
they
all
have
a
single
Ethernet port).
Networks are identified by a network address and a
netmask.
1.1.2
建模方法
The modeling approach
We
now
have
a
description
of
the
concepts
to
be
modeled
using
the
GME
metamodeling environment. The modeling
technique we are using is the well-known
and widely accepted Unified Modeling
Technology, especially a specific subset called
UML Class Diagrams.
（我们使用的建模
技术是众所周知和广泛接受的统一建模
技术，特别是一个叫做
U
ML
类图的特殊子集。
）
The
most
basic
step
in
the
metamodeling
process
consists
of
determining
two
things:
the
entities
used by
the
model,
and
the
relations
between
them.
Information
used to identify
and qualify certain entities and relations will be
assigned to them as
attributes.
Metamodeling, in a nutshell, is the mapping of
specification concepts onto
entities,
relations and attributes.
（元建模最基本的步骤由确定
2
件事情决定：模
型使用的实体，
以及实体间的相互关系。
用于确定和限定特定实体和相互关系的
信息将作为属性指定给它们。
简单的说，
元
建模就是将特定概念映射到实体、
相
互关系和属性。
）
We have been given
the specification
（
1.1.1
）
. Now let's describe the
modeling
paradigm:
is also an entity, one that
is always associated with (i.e. contained by) a
router.
The
model
will
contain
two
different
types
of
relations:
one
that
represents
connections between a network and a
router-port or host
(
association
), and one that
links
a
router
to
its
router-
ports
(
containment
).
The
main
difference
between
containment and association is that
contained entities are
and the
contained entity cannot exist without its
container.
Certain entities
have specific attributes. All of the attributes
are mentioned in the
specification,
such as
Luckily for us, the
networking specification in this example turned
out to be brief
and fairly precise. It
often takes much more to extract the essence of
the customer's
ideas.
1.1.3 Generic modeling concepts in GME
GME supports a set of
generic modeling concepts that are variations of
the UMT
entities, relationships, and
attributes. The differences reside partly in the
nomenclature
and
partly
in
additional
features,
semantics,
and
constraints
which
are
expected
to
guide
and simplify the metamodeling process.
Atoms
are
a
basic,
limited
type
of
entity.
The
name
indicates
that
it
has
no
internal
structure (i.e.
contained objects). Every feature of an atom that
can be represented in a model is
contained in the atom's name,
attributes, and the relations it participates in.
Models, the second generic
type of entity, are very similar to atoms. The
main difference lies in
the
ability
of
models
to
contain
atoms,
other
models,
and
other
types
of
objects.
Thus,
models
have
internal
structure.
When
viewed
together,
they
form
tree-like
containment
hierarchies
of
entities. Models can be
opened, showing a diagram of their internal
structure (Fig 1.2).
*
Please note that - mostly for historical reasons -
the term model has a double meaning in GME:
it denotes either the full description
of something (the artifact of a modeling project)
or a model
entity located somewhere in
a containment hierarchy of entities.
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