=Paper=
{{Paper
|id=Vol-247/paper-22
|storemode=property
|title=Towards more Reuse in Conceptual Modeling – A Combined Approach using Contexts
|pdfUrl=https://ceur-ws.org/Vol-247/FORUM_21.pdf
|volume=Vol-247
|dblpUrl=https://dblp.org/rec/conf/caise/BeckerJP07
}}
==Towards more Reuse in Conceptual Modeling – A Combined Approach using Contexts==
https://ceur-ws.org/Vol-247/FORUM_21.pdf
81
Towards more Reuse in Conceptual Modeling –
A Combined Approach using Contexts
Jörg Becker, Christian Janiesch, Daniel Pfeiffer
European Research Center for Information Systems, Leonardo-Campus 3,
48149 Münster, Germany
{becker, janiesch, pfeiffer}@ercis.de
Abstract. In this paper a novel reuse approach called context-based modeling is
proposed. Context-based modeling combines the reuse mechanisms
aggregation, restriction, and specialization. Context-based modeling aims at
both, minimal preparation of reuse combined with a high degree of guidance to
create suitable models. The proposal is conceptually explored.
Keywords: Meta modeling, conceptual modeling, component-based
development, reuse, context.
1 Reuse in Conceptual Modeling
Reuse in modeling means to apply the experience of other modelers or experiences
from former projects to approach an actual problem [8]. It implies that an existing
knowledge base is utilized to avoid starting from scratch. For the reuse of knowledge
within conceptual models different approaches have been developed: patterns (P),
components (CO), reference models (RM), and views (V) [1, 2, 6, 7, 9].
These reuse approaches apply the following reuse mechanisms: analogy
construction (AC), aggregation (A), configuration (C), specialization (S), instantiation
(I), and restriction (R) [2]. Table 1 maps the different reuse mechanisms to the
corresponding reuse approaches.
Table 1. Mapping of reuse mechanisms to reuse approaches.
Pattern Component Reference Model View
Analogy Construction P / AC RM / AC
Aggregation CO / A RM / A
Configuration RM / CF
Specialization P/S RM / S
Instantiation RM / I
Restriction RM / R V/R
A comparison of reuse mechanisms can be based on a classification according to two
dimensions: The first dimension is the degree of guidance; the second dimension is
the degree of preparation necessary to apply the mechanisms.
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The degree of preparation defines how much effort is necessary before a certain
mechanism can be used. To be able to apply the mechanism of configuration, rules
must be defined and the model elements must be annotated according to the rules.
This process is very time-consuming. The domains of valid values must be specified
for an instantiation of each placeholder. The mechanism of restriction requires the
specification of model element types that are permitted or disallowed. For
aggregation constraints can be defined which restrain the possible combinations of
components, but such rules are not obligatory. Specialization can exclude certain sorts
of modification and allows the general adaptation of models. Analogy construction
can always be applied and does not require any preparation.
The degree of guidance explains how much the modeler is assisted when a certain
mechanism is used. E.g. the guidance of configuration is very high. When the
parameters are filled with values the model can be configured automatically.
Interactions with the user are only necessary to resolve possible conflicts. Restriction
provides also a high guidance as model element can automatically be removed if their
corresponding types do not belong to the perspective which is applied to the model.
Instantiation specifies the domain of possible values but gives no hints what values to
choose in a certain situation. The guidance of aggregations and specialization
depends on whether any restrictions have been specified. It is to assume that an
increased degree of guidance requires in the same amount an increased degree of
preparation so that no overall gain can be achieved. Analogy construction offers no
instructions on how to proceed. In Fig. 1 the different reuse mechanisms are arranged
in a portfolio.
C
R
?
I
A
S
AC
high low
Degree of Preparation
Fig. 1. Portfolio of reuse mechanisms.
The objective of this paper is to construct a reuse approach that can be applied
without intensive preparation but that provides, nonetheless, a high degree of
guidance. The mechanisms restriction, aggregation and specialization are combined
since they seem to be the most promising ones to be used with a varying degree of
preparation. The result is a novel reuse approach called context-based modeling.
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2 Context-based Modeling
Core to context-based modeling is to model in redundant as well as complementary
contexts which each have distinct semantics. In this case, a context describes or
represents the environment in which the model or a component thereof has a certain
meaning.
A context-based modeling language comprises several contexts. A context acts as a
filter as well as a container. In its role as filter, it applies the mechanism of restriction
(R) to constrain the available constructs and their relations that can be used within an
instance of this context. A context can also be related to (subordinate or sibling)
contexts and, thus, applies the mechanism of aggregation (A). By the creation of these
relations, model constructs from different contexts are linked. (This entails on a
technical level that the contexts are only linked implicitly, since the explicit relations
are between the constructs, i. e. the model elements.) Specialization (S) can limit the
display of the aggregated components. But more commonly it rather comes into place
on a modeling level. If the aggregation and restriction of the model does not suffice
the individual needs, it is permissible to specialize the model by addition, deletion,
and modification of the existing elements.
Constructs from one context can be aggregated in other contexts. However, the
semantics and syntactics that specify the relations of the different constructs to each
other is unique to a context. For example, construct A, which is defined in context A’,
might also be allowed in context B’. However, C might be a subordinate construct to
A only in context A’. When linking construct A with constructs D of context D’, it is
possible to restrict this to A originating only from A’. A from context B’ cannot be
reused in context D’. Linking constructs – i.e. reusing or merely connecting them – is
enabled by so-called context rules. Cf. Fig. 2 for an overview.
Fig. 2. Exemplary definition of context rules between constructs in different contexts.
This leads to a distinction of different sorts of contexts. While A’ provides the basis
for all other contexts and does not reuse constructs of other contexts, it acts as a
foundation context. D’ is a context with multiple relations, i. e. it reuses components
from other contexts (A’) as well as its components are reused (E’). It acts as a link
context. Context E’ in comparison is not intended for reuse but acts as an aggregation
context which assembles components from other contexts as the highest node in a
model. Context B’ is uncommon since it is not integrated with other contexts; it acts
as a single context.
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3 Summary and Outlook
Core to context-based modeling proposal is to integrate the mechanisms of restriction,
aggregation and specialization. Aggregation is used in a very granular way since
model components from within contexts are assembled and contexts are only linked
implicitly. The interpretation of restrictions is less restrictive and their semantic
consistency lies within the requirements and competence of the modeling language
engineer. Furthermore, the mechanism of specialization is incorporated since model
component aggregation with explicit context rules allows for adaptations of the
resulting model. Contexts are supposed to offer adequate guidance on the reuse of
models with a lesser amount of model preparation than current isolated adaptation
approaches.
Context-based modeling has proven to be useful for the description of management
information systems [3] as well as web information systems [5]. Research suggests
that it can be a basis for the design of further situational modeling languages [4] and
that it can act as an innovative reuse mechanism.
Practically any existing modeling language can be transformed into a context-
based modeling language. Its meaningfulness, however, is strongly depending on the
purpose of the modeling endeavor as well as the original design of the modeling
language. As with all reuse mechanisms, certain types of modeling languages are
more suitable for a problem at hand than others.
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